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Background: Coronary microvascular disease is associated with adverse prognosis in a range of cardiovascular diseases, but its prognostic role in patients with aortic stenosis (AS) is unclear. The aim of this systematic review and meta-analysis is to determine the prognostic role of myocardial perfusion and coronary flow reserve, assessed using non-invasive imaging modalities, in patients with AS. Methods: We conducted a systematic review and meta-analysis of all studies assessing myocardial perfusion reserve (MPR) or coronary flow reserve (CFR) in patients with AS and reporting clinical outcomes, from inception to January 2024. The definition of abnormal MPR/CFR and major adverse cardiovascular events (MACE) was that used in each study. Estimates of effect were calculated from hazard ratios (HRs) and 95% confidence intervals (CIs) using a random-effects model. Results: Four studies comprising 384 participants met the inclusion criteria. Myocardial/coronary blood flow was assessed using Doppler echocardiography (n = 2), PET (n = 1), or cardiac magnetic resonance (n = 1). The median optimal cutoff for MPR/CFR across all studies was 2.01 (range 1.85–2.13), with 109 events. Impaired MPR/CFR was associated with a higher incidence of MACE (HR 3.67, 95% CI: 1.66, 8.09, I2 = 63%) in the overall population. Conclusions: Reduced MPR/CFR is associated with increased risk of MACE in patients with AS, although significant heterogeneity exists in published studies. Further studies are required to establish its role in the risk stratification of asymptomatic patients with AS. [ABSTRACT FROM AUTHOR]

Abstract Aortic valve replacement (AVR) leads to reverse cardiac remodeling in patients with aortic stenosis (AS). The aim of this secondary pooled analysis was to assess the degree and determinants of changes in myocardial perfusion post AVR, and its link with exercise capacity, in patients with severe AS. A total of 68 patients underwent same-day echocardiography and cardiac magnetic resonance imaging with adenosine stress pre and 6–12 months post-AVR. Of these, 50 had matched perfusion data available (age 67 ± 8 years, 86% male, aortic valve peak velocity 4.38 ± 0.63 m/s, aortic valve area index 0.45 ± 0.13cm2/m2). A subgroup of 34 patients underwent a symptom-limited cardiopulmonary exercise test (CPET) to assess maximal exercise capacity (peak VO2). Baseline and post-AVR parameters were compared and linear regression was used to determine associations between baseline variables and change in myocardial perfusion and exercise capacity. Following AVR, stress myocardial blood flow (MBF) increased from 1.56 ± 0.52 mL/min/g to 1.80 ± 0.62 mL/min/g (p

Aortic valve replacement (AVR) leads to reverse cardiac remodeling in patients with aortic stenosis (AS). The aim of this secondary pooled analysis was to assess the degree and determinants of changes in myocardial perfusion post AVR, and its link with exercise capacity, in patients with severe AS. A total of 68 patients underwent same-day echocardiography and cardiac magnetic resonance imaging with adenosine stress pre and 6–12 months post-AVR. Of these, 50 had matched perfusion data available (age 67 ± 8 years, 86% male, aortic valve peak velocity 4.38 ± 0.63 m/s, aortic valve area index 0.45 ± 0.13cm2/m2). A subgroup of 34 patients underwent a symptom-limited cardiopulmonary exercise test (CPET) to assess maximal exercise capacity (peak VO2). Baseline and post-AVR parameters were compared and linear regression was used to determine associations between baseline variables and change in myocardial perfusion and exercise capacity. Following AVR, stress myocardial blood flow (MBF) increased from 1.56 ± 0.52 mL/min/g to 1.80 ± 0.62 mL/min/g (p < 0.001), with a corresponding 15% increase in myocardial perfusion reserve (MPR) (2.04 ± 0.57 to 2.34 ± 0.68; p = 0.004). Increasing severity of AS, presence of late gadolinium enhancement, lower baseline stress MBF and MPR were associated with a greater improvement in MPR post-AVR. On multivariable analysis low baseline MPR was independently associated with increased MPR post-AVR. There was no significant change in peak VO2 post-AVR, but a significant increase in exercise duration. Change in MPR was associated with change in peak VO2 post AVR (r = 0.346, p = 0.045). Those with the most impaired stress MBF and MPR at baseline demonstrate the greatest improvements in these parameters following AVR and the magnitude of change in MPR correlated with improvement in peak VO2, the gold standard measure of aerobic exercise capacity. [ABSTRACT FROM AUTHOR]

Aim. To evaluate the potential of qualitative and semi-quantitative analysis of stress adenosine triphosphate perfusion cardiac magnetic resonance imaging (MRI) in patients with obstructive coronary artery disease (CAD) with stenosis ≥50%.Material and methods. Cardiac adenosine triphosphate perfusion stress MRI was performed in 49 patients with suspected or diagnosed CAD. The images were assessed qualitatively and semi-quantitatively. A zone of reduced signal intensity during the first passage of a contrast bolus with stress was taken as a stress-induced perfusion defect. Semiquantitative analysis was based on the construction of signal intensity curves of the contrast agent entering the left ventricular cavity and into the myocardium.Results. The detection of stress-induced perfusion defects according to cardiac stress MRI was significantly associated with coronary artery stenosis ≥50% (p

ABSTRACT: Background: Aerobic exercise capacity is an independent predictor of mortality in dilated cardiomyopathy (DCM), but the central mechanisms contributing to exercise intolerance in DCM are unknown. The aim of this study was to characterize coronary microvascular function in DCM and determine if cardiovascular magnetic resonance (CMR) measures are associated with aerobic exercise capacity. Methods: Prospective case-control comparison of adults with DCM and matched controls. Adenosine-stress perfusion CMR to assess cardiac structure, function and automated inline myocardial blood flow quantification, and cardiopulmonary exercise testing to determine peak VO2 was performed. Pre-specified multivariable linear regression, including key clinical and cardiac variables, was undertaken to identify independent associations with peak VO2. Results: Sixty-six patients with DCM (mean age 61 years, 47 male) were propensity-matched to 66 controls (mean age 59 years, 47 male) based on age, sex, body mass index, and diabetes. DCM patients had markedly lower peak VO2 (19.8 ± 5.5 versus 25.2 ± 7.3 mL/kg/min; P

ABSTRACT: Background: Quantitative stress cardiac magnetic resonance (CMR) can be performed using the dual-sequence (DS) technique or dual-bolus (DB) method. It is unknown if DS and DB produce similar results for myocardial blood flow (MBF) and myocardial perfusion reserve (MPR). The study objective is to investigate if there are any differences between DB- and DS-derived MBF and MPR. Methods: Retrospective observational study with 168 patients who underwent stress CMR. DB and DS methods were simultaneously performed on each patient on the same day. Global and segmental stress MBF and rest MBF values were collected. Results: Using Bland-Altman analysis, segmental and global stress MBF values were higher in DB than DS (0.22 ± 0.60 mL/g/min, p

We aimed to examine the associations of cardiovascular risk factors with myocardial perfusion reserve (MPR) in patients with type 2 diabetes and stable coronary artery disease. The study patients were retrospectively identified from a database of patients with diabetes and stable coronary artery disease at Asan Medical Center (Seoul, Republic of Korea), covering the period from 2017 to 2019. The primary outcome variable was MPR assessed by dynamic stress 201Tl/rest 99mTc-tetrofosmin SPECT. Univariable and stepwise multivariable analyses were performed to assess the associations of cardiovascular risk factors with MPR. A total of 276 patients (236 men and 40 women) were included. The median global MPR was 2.4 (interquartile range 1.9–3.0). Seventy-five (27.2%) patients had an MPR < 2.0. Multivariable linear regression showed that smoking (ß = − 0.44, 95% confidence interval − 0.68 to − 0.21, P < 0.001), hypertension (ß = − 0.24, 95% confidence interval − 0.47 to − 0.02, P = 0.033), and summed difference score (ß = − 0.05, 95% confidence interval − 0.07 to − 0.03, P < 0.001) were independently associated with MPR. Abnormal MPR (< 2.0) was associated with a higher incidence of cardiac death or myocardial infarction (P = 0.034). MPR assessed by dynamic stress 201Tl/rest 99mTc-tetrofosmin SPECT was impaired in a large cohort of patients with diabetes. After adjusting for risk variables, including standard myocardial perfusion imaging characteristics, smoking, and hypertension were associated with MPR. Our results may aid in identifying patients with impaired MPR and stratifying patients with type 2 diabetes. [ABSTRACT FROM AUTHOR]

Abstract Background Diffuse myocardial fibrosis and microvascular dysfunction are suggested to underlie cardiac dysfunction in patients with type 2 diabetes, but studies investigating their relative impact are lacking. We aimed to study imaging biomarkers of these and hypothesized that fibrosis and microvascular dysfunction would affect different phases of left ventricular (LV) diastole. Methods In this cross-sectional study myocardial blood flow (MBF) at rest and adenosine-stress and perfusion reserve (MPR), as well as extracellular volume fraction (ECV), were determined with cardiovascular magnetic resonance (CMR) imaging in 205 patients with type 2 diabetes and 25 controls. Diastolic parameters included echocardiography-determined lateral e’ and average E/e’, and CMR-determined (rest and chronotropic-stress) LV early peak filling rate (ePFR), LV peak diastolic strain rate (PDSR), and left atrial (LA) volume changes. Results In multivariable analysis adjusted for possible confounders including each other (ECV for blood flow and vice versa), a 10% increase of ECV was independently associated with ePFR/EDV (rest: β = − 4.0%, stress: β = − 7.9%), LAmax /BSA (rest: β = 4.8%, stress: β = 5.8%), and circumferential (β = − 4.1%) and radial PDSR (β = 0.07%/sec). A 10% stress MBF increase was associated with lateral e′ (β = 1.4%) and average E/e’ (β = − 1.4%) and a 10% MPR increase to lateral e′ (β = 2.7%), and average E/e’ (β = − 2.8%). For all the above, p

Aims Recently developed in-line automated cardiovascular magnetic resonance (CMR) myocardial perfusion mapping has been shown to be reproducible and comparable with positron emission tomography (PET), and can be easily integrated into clinical workflows. Bringing quantitative myocardial perfusion CMR into routine clinical care requires knowledge of sex- and age-specific normal values in order to define thresholds for disease detection. This study aimed to establish sex- and age-specific normal values for stress and rest CMR myocardial blood flow (MBF) in healthy volunteers. Methods and results A total of 151 healthy volunteers recruited from two centres underwent adenosine stress and rest myocardial perfusion CMR. In-line automatic reconstruction and post processing of perfusion data were implemented within the Gadgetron software framework, creating pixel-wise perfusion maps. Rest and stress MBF were measured, deriving myocardial perfusion reserve (MPR) and were subdivided by sex and age. Mean MBF in all subjects was 0.62 ± 0.13 mL/g/min at rest and 2.24 ± 0.53 mL/g/min during stress. Mean MPR was 3.74 ± 1.00. Compared with males, females had higher rest (0.69 ± 0.13 vs. 0.58 ± 0.12 mL/g/min, P < 0.01) and stress MBF (2.41 ± 0.47 vs. 2.13 ± 0.54 mL/g/min, P = 0.001). Stress MBF and MPR showed significant negative correlations with increasing age (r = −0.43, P < 0.001 and r = −0.34, P < 0.001, respectively). Conclusion Fully automated in-line CMR myocardial perfusion mapping produces similar normal values to the published CMR and PET literature. There is a significant increase in rest and stress MBF, but not MPR, in females and a reduction of stress MBF and MPR with advancing age, advocating the use of sex- and age-specific reference ranges for diagnostic use. [ABSTRACT FROM AUTHOR]

Background: Diffuse myocardial fibrosis and microvascular dysfunction are suggested to underlie cardiac dysfunction in patients with type 2 diabetes, but studies investigating their relative impact are lacking. We aimed to study imaging biomarkers of these and hypothesized that fibrosis and microvascular dysfunction would affect different phases of left ventricular (LV) diastole. Methods: In this cross-sectional study myocardial blood flow (MBF) at rest and adenosine-stress and perfusion reserve (MPR), as well as extracellular volume fraction (ECV), were determined with cardiovascular magnetic resonance (CMR) imaging in 205 patients with type 2 diabetes and 25 controls. Diastolic parameters included echocardiography-determined lateral e' and average E/e', and CMR-determined (rest and chronotropic-stress) LV early peak filling rate (ePFR), LV peak diastolic strain rate (PDSR), and left atrial (LA) volume changes. Results: In multivariable analysis adjusted for possible confounders including each other (ECV for blood flow and vice versa), a 10% increase of ECV was independently associated with ePFR/EDV (rest: β = − 4.0%, stress: β = − 7.9%), LAmax /BSA (rest: β = 4.8%, stress: β = 5.8%), and circumferential (β = − 4.1%) and radial PDSR (β = 0.07%/sec). A 10% stress MBF increase was associated with lateral e′ (β = 1.4%) and average E/e' (β = − 1.4%) and a 10% MPR increase to lateral e′ (β = 2.7%), and average E/e' (β = − 2.8%). For all the above, p < 0.05. No associations were found with longitudinal PDSR or left atrial total emptying fraction. Conclusion: In patients with type 2 diabetes, imaging biomarkers of microvascular dysfunction and diffuse fibrosis impacts diastolic dysfunction independently of each other. Microvascular dysfunction primarily affects early left ventricular relaxation. Diffuse fibrosis primarily affects diastasis. Trial registrationhttps://www.clinicaltrials.gov. Unique identifier: NCT02684331. Date of registration: February 18, 2016. [ABSTRACT FROM AUTHOR]

Abstract Background Type 2 diabetes (T2D) and hypertension commonly coexist and are associated with subclinical myocardial structural and functional changes. We sought to determine the association between blood pressure (BP) and left ventricular (LV) remodeling, systolic/diastolic function, and coronary microvascular function, among individuals with T2D without prevalent cardiovascular disease. Methods Participants with T2D and age-, sex-, and ethnicity-matched controls underwent comprehensive cardiovascular phenotyping including fasting bloods, transthoracic echocardiography, cardiovascular magnetic resonance imaging with quantitative adenosine stress/rest perfusion, and office and 24-h ambulatory BP monitoring. Multivariable linear regression was performed to determine independent associations between BP and imaging markers of remodeling and function in T2D. Results Individuals with T2D (n = 205, mean age 63 ± 7 years) and controls (n = 40, mean age 61 ± 8 years) were recruited. Mean 24-h systolic BP, but not office BP, was significantly greater among those with T2D compared to controls (128.8 ± 11.7 vs 123.0 ± 13.1 mmHg, p = 0.006). Those with T2D had concentric LV remodeling (mass/volume 0.91 ± 0.15 vs 0.82 ± 0.11 g/mL, p

Background: Type 2 diabetes (T2D) and hypertension commonly coexist and are associated with subclinical myocardial structural and functional changes. We sought to determine the association between blood pressure (BP) and left ventricular (LV) remodeling, systolic/diastolic function, and coronary microvascular function, among individuals with T2D without prevalent cardiovascular disease. Methods: Participants with T2D and age-, sex-, and ethnicity-matched controls underwent comprehensive cardiovascular phenotyping including fasting bloods, transthoracic echocardiography, cardiovascular magnetic resonance imaging with quantitative adenosine stress/rest perfusion, and office and 24-h ambulatory BP monitoring. Multivariable linear regression was performed to determine independent associations between BP and imaging markers of remodeling and function in T2D. Results: Individuals with T2D (n = 205, mean age 63 ± 7 years) and controls (n = 40, mean age 61 ± 8 years) were recruited. Mean 24-h systolic BP, but not office BP, was significantly greater among those with T2D compared to controls (128.8 ± 11.7 vs 123.0 ± 13.1 mmHg, p = 0.006). Those with T2D had concentric LV remodeling (mass/volume 0.91 ± 0.15 vs 0.82 ± 0.11 g/mL, p < 0.001), decreased myocardial perfusion reserve (2.82 ± 0.83 vs 3.18 ± 0.82, p = 0.020), systolic dysfunction (global longitudinal strain 16.0 ± 2.3 vs 17.2 ± 2.1%, p = 0.004) and diastolic dysfunction (E/e' 9.30 ± 2.43 vs 8.47 ± 1.53, p = 0.044) compared to controls. In multivariable regression models adjusted for 14 clinical variables, mean 24-h systolic BP was independently associated with concentric LV remodeling (β = 0.165, p = 0.031), diastolic dysfunction (β = 0.273, p < 0.001) and myocardial perfusion reserve (β = − 0.218, p = 0.016). Mean 24-h diastolic BP was associated with LV concentric remodeling (β = 0.201, p = 0.016). Conclusion: 24-h ambulatory systolic BP, but not office BP, is independently associated with cardiac remodeling, coronary microvascular dysfunction, and diastolic dysfunction among asymptomatic individuals with T2D. (Clinical trial registration. URL: https://clinicaltrials.gov/ct2/show/NCT03132129 Unique identifier: NCT03132129). [ABSTRACT FROM AUTHOR]

Abstract Background Quantification of myocardial blood flow (MBF) and myocardial perfusion reserve (MPR) by cardiovascular magnetic resonance (CMR) perfusion requires sampling of the arterial input function (AIF). While variation in the AIF sampling location is known to impact quantification by CMR and positron emission tomography (PET) perfusion, there is no evidence to support the use of a specific location based on their diagnostic accuracy in the detection of coronary artery disease (CAD). This study aimed to evaluate the accuracy of stress MBF and MPR for different AIF sampling locations for the detection of abnormal myocardial perfusion with expert visual assessment as the reference. Methods Twenty-five patients with suspected or known CAD underwent vasodilator stress-rest perfusion with a dual-sequence technique at 3T. A low-resolution slice was acquired in 3-chamber view to allow AIF sampling at five different locations: left atrium (LA), basal left ventricle (bLV), mid left ventricle (mLV), apical left ventricle (aLV) and aortic root (AoR). MBF and MPR were estimated at the segmental level using Fermi function-constrained deconvolution. Segments were scored as having normal or abnormal perfusion by visual assessment and the diagnostic accuracy of stress MBF and MPR for each location was evaluated using receiver operating characteristic curve analysis. Results In both normal (300 out of 400, 75 %) and abnormal segments, rest MBF, stress MBF and MPR were significantly different across AIF sampling locations (p

Abstract Background Coronary microvascular dysfunction (CMD) is an important underlying cause of angina pectoris. Currently, no diagnostic tool is available to directly visualize the coronary microvasculature. Invasive microvascular reactivity testing is the diagnostic standard for CMD, but several non-invasive imaging techniques are being evaluated. However, evidence on reported non-invasive parameters and cut-off values is limited. Thus, we aimed to provide an overview of reported non-invasive parameters and corresponding cut-off values for CMD. Methods Pubmed and EMBASE databases were systematically searched for studies enrolling patients with angina pectoris without obstructed coronary arteries, investigating at least one non-invasive imaging technique to quantify CMD. Methodological quality assessment of included studies was performed using QUADAS-2. Results Thirty-seven studies were included. Ten cardiac magnetic resonance studies reported MPRI and nine positron emission tomography (PET) and transthoracic echocardiography (TTE) studies reported CFR. Mean MPRI ranged from 1.47 ± 0.36 to 2.01 ± 0.41 in patients and from 1.50 ± 0.47 to 2.68 ± 0.49 in controls without CMD. Reported mean CFR in PET and TTE ranged from 1.39 ± 0.31 to 2.85 ± 1.35 and 1.69 ± 0.40 to 2.40 ± 0.40 for patients, and 2.68 ± 0.83 to 4.32 ± 1.78 and 2.65 ± 0.65 to 3.31 ± 1.10 for controls, respectively. Conclusions This systematic review summarized current evidence on reported parameters and cut-off values to diagnose CMD for various non-invasive imaging modalities. In current clinical practice, CMD is generally diagnosed with a CFR less than 2.0. However, due to heterogeneity in methodology and reporting of outcome measures, outcomes could not be compared and no definite reference values could be provided.

Children with Friedreich's ataxia (FA) are at risk of perioperative morbidity and mortality from severe unpredictable heart failure. There is currently no clear way of identifying patients at highest risk. We used myocardial perfusion reserve (MPR), an MRI technique used to assess the maximal myocardial blood flow above baseline, to help determine potential surgical risk in FA subjects. In total, seven children with genetically confirmed FA, ages 8–17 years, underwent MPR stress testing using regadenoson. Six of the seven demonstrated impaired endocardial perfusion during coronary hyperemia. The same six were also found to have evidence of ongoing myocardial damage as illustrated by cardiac troponin I leak (range 0.04–0.17 ng/mL, normal < 0.03 ng/mL). None of the patients had a reduced ejection fraction (range 59–74%) or elevated insulin level (range 2.46–14.23 mCU/mL). This retrospective study shows that children with FA develop MPR defects early in the disease process. It also suggests MPR may be a sensitive tool to evaluate underlying cardiac compromise and could be of use in directing surgical management decisions in children with FA. [ABSTRACT FROM AUTHOR]

Functional coronary disorders such as coronary spasm and microvascular dysfunction (including microvascular spasm and impaired microvascular dilatation) are frequent findings among patients with angina and non-obstructed coronary arteries (ANOCA). In this study, we investigated a potential association of coronary spasm and myocardial perfusion abnormalities as well as predictors of such functional coronary disorders in ANOCA patients using a multimodality diagnostic strategy including adenosine stress CMR and intracoronary acetylcholine testing. We enrolled 129 patients with ANOCA who underwent acetylcholine testing and adenosine stress perfusion CMR. Patients were allocated to 3 groups according to their spasm testing result with regard to standardized COVADIS criteria: 1) epicardial spasm, 2) microvascular spasm, and 3) no spasm. The myocardial perfusion reserve index (MPRI) was semiquantitatively determined from adenosine stress perfusion CMR. Multivariate regression analyses were performed to identify predictors of coronary functional disorders. Patients with epicardial spasm had lower MPRI than patients without, whereas MPRI was preserved in patients with microvascular spasm. Multivariate analyses revealed age, previous myocardial infarction, LVEF and epicardial spasm as independent predictors of diminished MPRI, whereas previous PCI was associated with epicardial spasm, and female sex was a strong predictor of microvascular spasm. Our results demonstrate coexistence of different functional coronary disorder endotypes involving the macro- and microvascular level of the coronary circulation in patients with ANOCA. We demonstrate that epicardial spasm is associated with diminished myocardial perfusion reserve and report further predictors of coronary functional disorders. • Assessment of vasomotor dysfunction by CMR and acetylcholine testing is feasible. • Coronary artery spasm and impaired microvascular vasodilation coexist. • Age and previous myocardial infarction are independent predictors of low MPRI. • Epicardial spasm is associated with low MPRI. • Prior PCI is predictive for epicardial spasm and female sex for microvascular spasm. [ABSTRACT FROM AUTHOR]

The term chronic coronary syndromes encompasses a variety of clinical presentations of coronary artery disease (CAD), ranging from stable angina due to epicardial coronary artery disease to microvascular coronary dysfunction. Cardiac magnetic resonance (CMR) imaging has an established role in the diagnosis, prognostication and treatment planning of patients with CAD. Recent advances in parametric mapping CMR techniques have added value in the assessment of patients with chronic coronary syndromes, even without the need for gadolinium contrast administration. Furthermore, quantitative perfusion CMR techniques have enabled the non-invasive assessment of myocardial blood flow and myocardial perfusion reserve and can reliably identify multivessel coronary artery disease and microvascular dysfunction. This review summarizes the clinical applications and the prognostic value of the novel CMR parametric mapping techniques in the setting of chronic coronary syndromes and discusses their strengths, pitfalls and future directions.

Purpose: The identification of coronary vascular dysfunction may enhance risk stratification in patients with resistant hypertension (RH). We evaluated if impaired coronary vascular function, assessed by rubidium-82 (82Rb) positron emission tomography/computed tomography (PET/CT) imaging, is associated with increased cardiovascular risk in patients with hypertension without overt coronary artery disease (CAD). Methods: We studied 517 hypertensive subjects, 26% with RH, without overt CAD, and with normal stress-rest myocardial perfusion imaging at 82Rb PET/CT. The outcome end points were cardiac death, nonfatal myocardial infarction, coronary revascularization, and admission for heart failure. Results: Over a median of 38 months (interquartile range 26 to 50), 21 cardiac events (4.1% cumulative event rate) occurred. Patients with RH were older (p < 0.05) and had a higher prevalence of left ventricular hypertrophy (p < 0.001), a lower hyperemic myocardial blood flow (MBF), and myocardial perfusion reserve (MPR) (both p < 0.001) compared to those without. Conversely, coronary artery calcium content and baseline MBF were not different between patients with and without RH. At univariable Cox regression analysis, age, RH, left ventricular ejection fraction, coronary artery calcium score, and reduced MPR were significant predictors of events. At multivariable analysis, age, RH, and reduced MPR (all p < 0.05) were independent predictors of events. Patients with RH and reduced MPR had the highest risk of events and the major risk acceleration over time. Conclusion: The findings suggest that the assessment of coronary vascular function may enhance risk stratification in patients with hypertension. [ABSTRACT FROM AUTHOR]

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Aim. To assess the role of global and selected scintigraphic scores of myocardial perfusion, blood flow and reserve in the anatomical and functional significance of coronary artery (CA) stenosis.Material and methods. The double-blind comparative study included 23 patients (mean age 61,2±6,8 years, 12 (52%) women, 11 (48%) men). All patients underwent stress dynamic single-photon emission computed tomography (SPECT) with adenosine triphosphate (ATP) (140 µg/kg/min in 6 minutes). Myocardial perfusion disorders were assessed by a semi-quantitative method, the total Summed Stress Score (SSS), the Summed Rest Score (SRS), and the Summed Difference Score (SDS) were determined. Global (g) and regional (r) myocardial perfusion (MP) were evaluated; myocardial perfusion reserve (MPR) was calculated as the ratio of MP at stress and at rest. Coronary angiography (CAG) was performed within 1 week after SPECT, the amount of CA narrowing was evaluated by diameter. Stenoses >50% were considered anatomically significant. The assessment of the fractional flow reserve (FFR) was performed by the ratio of the mean intracoronary pressure at the CA ostia to the pressure distal to the stenosis at the ATP infusion peak. FFR ≤0,80 was considered a sign of hemodynamically significant stenosis. Results. Neither regional nor global scintigraphic scores reflecting myocardial perfusion showed statistical significance as markers of CA stenosis >50%. Among perfusion markers, only SSSg (>4) showed good sensitivity and specificity in the diagnosis of hemodynamically significant (FFR ≤0,80) stenoses (AUC 0,76; p=0,002; sensitivity 81,8%, specificity 83,3%). The following regional flow scores allowed identification of hemodynamically significant CA: stress MPr ≤0,54 ml/min/g (AUC 0,8; p=0,0003; sensitivity 57%, specificity 92%) and MPR ≤1,5 (AUC 0,86; p< 0,0001; sensitivity 71,4%, specificity 92,8%).Conclusion. It is proved that global and regional scintigraphic scores of MP and MPR are sensitive and specific markers of hemodynamically significant (FFR ≤0,80) coronary stenosis. It can be more useful for localization diagnosis of the lesion than standard SPECT.

Abstract Background Adenosine is used in stress perfusion cardiac imaging to reveal myocardial ischemia by its vasodilator effects. Caffeine is a competitive antagonist of adenosine. However, previous studies reported inconsistent results about the influence of caffeine on adenosine's vasodilator effect. This study assessed the impact of caffeine on the myocardial perfusion reserve index (MPRI) using adenosine stress cardiovascular magnetic resonance imaging (CMR). Moreover, we sought to evaluate if the splenic switch-off sign might be indicative of prior caffeine consumption. Methods Semiquantitative perfusion analysis was performed in 25 patients who underwent: 1) caffeine-naïve adenosine stress CMR demonstrating myocardial ischemia and, 2) repeat adenosine stress CMR after intake of caffeine. MPRI (global; remote and ischemic segments), and splenic perfusion ratio (SPR) were assessed and compared between both exams. Results Global MPRI after caffeine was lower vs. caffeine-naïve conditions (1.09 ± 0.19 vs. 1.24 ± 0.19; p

Background: Whether estimates of myocardial perfusion reserve (MPR) stemming from new-generation cadmium-zinc-telluride (CZT) cameras are accurate remains unclear. Methods: We queried our institutional database for patients undergoing MPR with CZT cameras. The primary goal was appraising the incremental diagnostic yield of MPR on top or at odds of maximal ischemia score (MIS). Results: A total of 66 subjects were included. When distinguishing patients according to normal vs abnormal MPR (cut-off 2.1 mL/min/g) and normal vs abnormal MIS, 4 groups could be identified: 12 (18.1%) individuals with normal MPR and MIS, 12 (18.1%) with normal MPR and abnormal MIS, 16 (24.2%) with abnormal MPR and normal MIS, and 26 (39.4%) with abnormal MPR and MIS. MIS was significantly associated with several baseline features, whereas MPR did not. There was no significant association between MPR and MIS, nor with regional perfusion. Clinical outcomes were uncommon and not significantly associated with MPR or MIS, whereas angiographically significant coronary artery disease (CAD) was associated solely with MIS (P < 0.05), and not with MPR. Conclusions: There is limited agreement between CZT-derived MPR and baseline risk, perfusion and angiography results. Whether such discrepancies may still prove incrementally beneficial for the diagnosis or prognosis of CAD remains unclear. [ABSTRACT FROM AUTHOR]

Ischemia with no obstructive coronary artery disease (INOCA) is prevalent in women and is associated with increased risk of developing heart failure with preserved ejection fraction (HFpEF); however, the mechanism(s) contributing to this progression remains unclear. Given that diastolic dysfunction is common in women with INOCA, defining mechanisms related to diastolic dysfunction in INOCA could identify therapeutic targets to prevent HFpEF. Cardiac MRI was performed in 65 women with INOCA and 12 reference controls. Diastolic function was defined by left ventricular early diastolic circumferential strain rate (eCSRd). Contributors to diastolic dysfunction were chosen a priori as coronary vascular dysfunction (myocardial perfusion reserve index [MPRI]), diffuse myocardial fibrosis (extracellular volume [ECV]), and aortic stiffness (aortic pulse wave velocity [aPWV]). Compared to controls, eCSRd was lower in INOCA (1.61 ± 0.33/s vs. 1.36 ± 0.31/s, P = 0.016); however, this difference was not exaggerated when the INOCA group was sub-divided by low and high MPRI (P > 0.05) nor was ECV elevated in INOCA (29.0 ± 1.9% vs. 28.0 ± 3.2%, control vs. INOCA; P = 0.38). However, aPWV was higher in INOCA vs. controls (8.1 ± 3.2 m/s vs. 6.1 ± 1.5 m/s; P = 0.045), and was associated with eCSRd (r = −0.50, P < 0.001). By multivariable linear regression analysis, aPWV was an independent predictor of decreased eCSRd (standardized β = −0.39, P = 0.003), as was having an elevated left ventricular mass index (standardized β = −0.25, P = 0.024) and lower ECV (standardized β = 0.30, P = 0.003). These data provide mechanistic insight into diastolic dysfunction in women with INOCA, identifying aortic stiffness and ventricular remodeling as putative therapeutic targets. • INOCA is prevalent in women and is associated with increased risk of developing HFpEF. • The mechanism(s) contributing to heart failure progression in women with INOCA remains unclear. • Here we show that elevated aotric stiffness is an independent predictor of impaired diastolic function in INOCA. [ABSTRACT FROM AUTHOR]

Background: Quantification of myocardial blood flow (MBF) and myocardial perfusion reserve (MPR) by cardiovascular magnetic resonance (CMR) perfusion requires sampling of the arterial input function (AIF). While variation in the AIF sampling location is known to impact quantification by CMR and positron emission tomography (PET) perfusion, there is no evidence to support the use of a specific location based on their diagnostic accuracy in the detection of coronary artery disease (CAD). This study aimed to evaluate the accuracy of stress MBF and MPR for different AIF sampling locations for the detection of abnormal myocardial perfusion with expert visual assessment as the reference. Methods: Twenty-five patients with suspected or known CAD underwent vasodilator stress-rest perfusion with a dual-sequence technique at 3T. A low-resolution slice was acquired in 3-chamber view to allow AIF sampling at five different locations: left atrium (LA), basal left ventricle (bLV), mid left ventricle (mLV), apical left ventricle (aLV) and aortic root (AoR). MBF and MPR were estimated at the segmental level using Fermi function-constrained deconvolution. Segments were scored as having normal or abnormal perfusion by visual assessment and the diagnostic accuracy of stress MBF and MPR for each location was evaluated using receiver operating characteristic curve analysis. Results: In both normal (300 out of 400, 75 %) and abnormal segments, rest MBF, stress MBF and MPR were significantly different across AIF sampling locations (p < 0.001). Stress MBF for the AoR (normal: 2.42 (2.15–2.84) mL/g/min; abnormal: 1.71 (1.28–1.98) mL/g/min) had the highest diagnostic accuracy (sensitivity 80 %, specificity 85 %, area under the curve 0.90; p < 0.001 versus stress MBF for all other locations including bLV: normal: 2.78 (2.39–3.14) mL/g/min; abnormal: 2.22 (1.83–2.48) mL/g/min; sensitivity 91 %, specificity 63 %, area under the curve 0.81) and performed better than MPR for the LV locations (p < 0.01). MPR for the AoR (normal: 2.43 (1.95–3.14); abnormal: 1.58 (1.34–1.90)) was not superior to MPR for the bLV (normal: 2.59 (2.04–3.20); abnormal: 1.69 (1.36–2.14); p = 0.717). Conclusions: The AIF sampling location has a significant impact on MBF and MPR estimates by CMR perfusion, with AoR-based stress MBF comparing favorably to that for the current clinical reference bLV. [ABSTRACT FROM AUTHOR]

Background: Myocardial perfusion is evaluated in first‐pass MRI using a gadolinium‐based contrast agent, which limits its repeatability and restricts its use in patients with abnormal kidney function. Arterial spin labeling (ASL) is a promising technique for measuring myocardial perfusion without contrast injection. The ratio of stress to rest perfusion, termed myocardial perfusion reserve (MPR), is an indicator of the severity of stenosis in patients with coronary artery disease (CAD). Purpose: To quantify perfusion increases with pharmacological vasodilation, explore MPR differences between segments with and without perfusion defects, and examine the correlations between quantitative ASL and semiquantitative first‐pass measurements. Study Type: Prospective. Subjects: Sixteen patients with suspected CAD: 10 classified as "healthy," having normal perfusion on first‐pass and no enhancement on late gadolinium enhancement (LGE), and six as "nonhealthy," having hypoperfused segments including ischemic and infarcted. Field Strength/Sequence: Flow‐sensitive alternating inversion recovery (FAIR) rest–stress cardiac ASL with balanced steady‐state free precession (bSSFP), rest–stress first‐pass imaging using gradient‐echo and LGE using a phase‐sensitive inversion‐recovery bSSFP at 1.5T. Assessment: For healthy subjects, rest–stress perfusion data were compared in global, coronary artery territory, and segment regions of interest (ROIs). A segmental MPR comparison was performed between normal segments from healthy subjects and abnormal segments from nonhealthy subjects. Correlations between ASL and first‐pass parameters were explored. Statistical Tests: Wilcoxon‐signed‐rank test, nonparametric factorial analysis of variance (ANOVA), and Pearson's/Spearman's correlations. Results: Perfusion increases were significant globally (P = 0.005), per coronary artery territory (P = 0.015), and per segment (P = 0.03 for all segments in ASL and first‐pass, except anteroseptal in ASL P = 0.04). MPR differences between normal and abnormal segments were significant (P = 0.0028: ASL, P = 0.033: first‐pass). ASL and first‐pass measurements were correlated (MPR: r = 0.64, P = 0.008 and perfusion: rho = 0.47, P = 0.007). Data Conclusion: This study demonstrates the feasibility of ASL to detect hyperemia, the potential to differentiate segments with and without perfusion defects, and significant correlations between ASL and semiquantitative first‐pass. Level of Evidence: 2 Technical Efficacy Stage: 1 [ABSTRACT FROM AUTHOR]

Abstract Background Non-invasive assessment of myocardial ischaemia is a cornerstone of the diagnosis of coronary artery disease. Measurement of myocardial blood flow (MBF) using positron emission tomography (PET) is the current reference standard for non-invasive quantification of myocardial ischaemia. Dynamic myocardial perfusion cardiovascular magnetic resonance (CMR) offers an alternative to PET and a recently developed method with automated inline perfusion mapping has shown good correlation of MBF values between CMR and PET. This study assessed the repeatability of myocardial perfusion mapping by CMR in healthy subjects. Methods Forty-two healthy subjects were recruited and underwent adenosine stress and rest perfusion CMR on two visits. Scans were repeated with a minimum interval of 7 days. Intrastudy rest and stress MBF repeatability were assessed with a 15-min interval between acquisitions. Interstudy rest and stress MBF and myocardial perfusion reserve (MPR) were measured for global myocardium and regionally for coronary territories and slices. Results There was no significant difference in intrastudy repeated global rest MBF (0.65 ± 0.13 ml/g/min vs 0.62 ± 0.12 ml/g/min, p = 0.24, repeatability coefficient (RC) =24%) or stress (2.89 ± 0.56 ml/g/min vs 2.83 ± 0.64 ml/g/min, p = 0.41, RC = 29%) MBF. No significant difference was seen in interstudy repeatability for global rest MBF (0.64 ± 0.13 ml/g/min vs 0.64 ± 0.15 ml/g/min, p = 0.80, RC = 32%), stress MBF (2.71 ± 0.61 ml/g/min vs 2.55 ± 0.57 ml/g/min, p = 0.12, RC = 33%) or MPR (4.24 ± 0.69 vs 3.73 ± 0.76, p = 0.25, RC = 36%). Regional repeatability was good for stress (RC = 30–37%) and rest MBF (RC = 32–36%) but poorer for MPR (RC = 35–43%). Within subject coefficient of variation was 8% for rest and 11% for stress within the same study, and 11% for rest and 12% for stress between studies. Conclusions Fully automated, inline, myocardial perfusion mapping by CMR shows good repeatability that is similar to the published PET literature. Both rest and stress MBF show better repeatability than MPR, particularly in regional analysis.

Background: A significant number of women with angina and no obstructive coronary artery disease (CAD; <50% stenosis) have coronary microvascular dysfunction (CMD) which carries an adverse cardiovascular prognosis. Coronary microvascular function can be evaluated by transthoracic Doppler echocardiography (TTDE) as a coronary flow velocity reserve (CFVR) and by static CT myocardial perfusion (CTP) as a myocardial perfusion reserve (MPR). Whether these methods are correlated is not known. We assessed the correlation between CFVR and MPR and investigated whether women with angina, CMD and no obstructive CAD have reduced MPR compared with asymptomatic women. Methods: Static CTP with adenosine‐induced vasodilation and TTDE of the left anterior descending artery with dipyridamole‐induced vasodilation were successfully performed and analysed in 99 women with stable angina and no obstructive CAD and 33 asymptomatic women with no obstructive CAD. CMD was defined as CFVR < 2. Results: Correlation between rate‐pressure product corrected MPR and CFVR was weak but significant (r =.23; p =.007). MPR was highest among asymptomatic women with normal CFVR (median [interquartile range; IQR] 158 [145–181] %). Symptomatic women with normal CFVR had reduced MPR (148 [134–162] %; age‐adjusted p <.001); however, the lowest MPR was found in symptomatic women with CMD (140 [129–164] %; age‐adjusted p <.001), independent of cardiovascular risk factors and haemodynamic parameters (p =.017). Conclusion: Women with angina, CMD and no obstructive CAD had markedly diminished MPR compared with asymptomatic women. Correlation between CFVR and MPR was weak, suggesting that CTP and TTDE are not interchangeable for detection of CMD. [ABSTRACT FROM AUTHOR]

Aims Coronary microvascular disease (CMD) is a known complication in type 2 diabetes mellitus (T2DM). We examined the relationship between diabetic complications, left ventricular (LV) function and structure and myocardial perfusion reserve (MPR) as indicators of CMD in patients with T2DM and control subjects. Methods and results This was a cross-sectional study of 193 patients with T2DM and 25 controls subjects. Patients were grouped as uncomplicated diabetes (n  = 71) and diabetes with complications (albuminuria, retinopathy, and autonomic neuropathy). LV structure, function, adenosine stress, and rest myocardial perfusion were evaluated by cardiovascular magnetic resonance. Echocardiography was used to evaluate diastolic function. Patients with uncomplicated T2DM did not have significantly different LV mass and E/e* but decreased MPR (3.8 ± 1.0 vs. 5.1 ± 1.5, P  < 0.05) compared with controls. T2DM patients with albuminuria and retinopathy had decreased MPR (albuminuria: 2.4 ± 0.9 and retinopathy 2.6 ± 0.7 vs. 3.8 ± 1.0, P  < 0.05 for both) compared with uncomplicated T2DM patients, along with significantly higher LV mass (149 ± 39 and 147 ± 40 vs. 126 ± 33 g, P  < 0.05) and E/e* (8.3 ± 2.8 and 8.1 ± 2.2 vs. 7.0 ± 2.5, P  < 0.05). When entered in a multiple regression model, reduced MPR was associated with increasing E/e* and albuminuria and retinopathy were associated with reduced MPR. Conclusions Patients with uncomplicated T2DM have reduced MPR compared with control subjects, despite equivalent LV mass and E/e*. T2DM patients with albuminuria or retinopathy have reduced MPR and increased LV mass and E/e* compared with patients with uncomplicated T2DM. E/e* and MPR are significantly associated after adjustment for age, hypertension, and LV mass, suggesting a link between CMD and cardiac diastolic function. Clinical trial registration https://www.clinicaltrials.org. Unique identifier: NCT02684331 [ABSTRACT FROM AUTHOR]

Background: We measured myocardial blood flow (MBF) and myocardial perfusion reserve (MPR) by a dynamic low-dose CZT-SPECT protocol in patients with suspected or known coronary artery disease (CAD) and investigated the capability of dynamic data in predicting obstructive CAD. A total of 173 patients with suspected or known CAD underwent dynamic CZT-SPECT after the injection of 155 MBq and 370 MBq of 99mTc-sestamibi for rest and stress imaging, respectively. Standard rest and stress imaging were performed at the end of each dynamic scan. A total perfusion defect (TPD) < 5% were considered normal. Obstructive CAD was defined as ≥ 70% stenosis at coronary angiography. Results: Global MPR was lower (p < 0.05) in patients with abnormal compared with those with normal MPI (2.40 ± 0.7 vs. 2.70 ± 0.8). A weak, albeit significant correlation between TPD and MPR (r = − 0.179, p < 0.05) was found. In 91 patients with available angiographic data, hyperemic MBF (2.59 ± 1.2 vs. 3.24 ± 1.1 ml/min/g) and MPR (1.96 ± 0.7 vs. 2.74 ± 0.9) were lower (both p < 0.05) in patients with obstructive CAD (n = 21) compared with those without (n = 70). At univariable analysis, TPD, hyperemic MBF, and MPR were significant predictors of obstructive CAD, whereas only MPR was independent predictor at multivariable analysis (p < 0.05). At per vessels analysis, regional hyperemic MBF (2.59 ± 1.2 vs. 3.24 ± 1.1 ml/min/g) and regional MPR (1.96 ± 0.7 vs. 2.74 ± 0.9) were lower in the 31 vessels with obstructive CAD compared with 242 vessels without (both p < 0.05). Conclusions: In patients with suspected or known CAD, MPR assessed by low-dose dynamic CZT-SPECT showed a good correlation with myocardial perfusion imaging findings and it could be useful to predict obstructive CAD. [ABSTRACT FROM AUTHOR]

Purpose: Cardiac imaging with positron emission tomography/computed tomography (PET/CT) allows measurement of coronary artery calcium (CAC), stress-induced myocardial ischemia and myocardial perfusion reserve (MPR). We evaluated the prognostic role of the combined assessment of regional CAC score, ischemic total perfusion defect (ITPD) and MPR in predicting lesion-related outcome in patients with suspected coronary artery disease (CAD). Methods: We studied 206 patients with suspected CAD referred to 82Rb PET/CT cardiac imaging and available coronary angiographic data. The outcome end points were cardiac death, target vessel-related myocardial infarction or coronary revascularization. Results: Compared to vessels without event, those with event showed higher CAC score and ITPD, and lower hyperemic myocardial blood flow and MPR (all p < 0.001). At Cox regression multivariable analysis, significant CAD (≥50% stenosis) (p < 0.001), CAC score ≥ 300 (p < 0.01) and MPR <2 (p < 0.01) were independent predictors of events. The decision trees analysis for the identification of events produced five terminal nodes. The initial split was on CAC score values. For vessels with CAC <300 and MPR ≥2, no further split was performed, while vessels with CAC <300 and MPR <2 were further stratified by ITPD. For vessels with CAC ≥300 a further stratification was performed only by MPR. The worst prognosis was observed in vessels with CAC ≥300 and MPR <2 and in vessels with CAC <300, MPR <2 and ITPD ≥5%. Conclusion: The combination of CAC score and MPR is useful to predict the lesion-related outcome in the presence of significant CAD. [ABSTRACT FROM AUTHOR]

Purpose: Bolus‐based dynamic contrast agent (CA) perfusion measurements of the heart are subject to systematic errors due to CA bolus dispersion in the coronary arteries. To better understand these effects on quantification of myocardial blood flow and myocardial perfusion reserve (MPR), an in‐silico model of the coronary arteries down to the pre‐arteriolar vessels has been developed. Methods: In this work, a computational fluid dynamics analysis is performed to investigate these errors on the basis of realistic 3D models of the left and right porcine coronary artery trees, including vessels at the pre‐arteriolar level. Using advanced boundary conditions, simulations of blood flow and CA transport are conducted at rest and under stress. These are evaluated with regard to dispersion (assessed by the width of CA concentration time curves and associated vascular transport functions) and errors of myocardial blood flow and myocardial perfusion reserve quantification. Results: Contrast agent dispersion increases with traveled distance as well as vessel diameter, and decreases with higher flow velocities. Overall, the average myocardial blood flow errors are −28% ± 16% and −8.5% ± 3.3% at rest and stress, respectively, and the average myocardial perfusion reserve error is 26% ± 22%. The calculated values are different in the left and right coronary tree. Conclusion: Contrast agent dispersion is dependent on a complex interplay of several different factors characterizing the cardiovascular bed, including vessel size and integrated vascular length. Quantification errors evoked by the observed CA dispersion show nonnegligible distortion in dynamic CA bolus‐based perfusion measurements. We expect future improvements of quantitative perfusion measurements to make the systematic errors described here more apparent. [ABSTRACT FROM AUTHOR]

• Quantification of myocardial blood flow is possible using a cadmium-zinc-telluride (CZT) camera. • Myocardial perfusion reserve is associated with number of coronary artery disease. • Dynamic single-photon emission computed tomography using a CZT camera can identify occult coronary artery disease. Relative myocardial perfusion imaging can misdiagnose "balanced" ischemia caused by coronary artery disease (CAD). We assessed the feasibility of myocardial blood flow (MBF) and myocardial perfusion reserve (MPR) using dynamic single-photon emission computed tomography (SPECT) with a cadmium-zinc-telluride (CZT) camera for estimating underlying CAD in patients with normal stress myocardial perfusion SPECT (MPS). 125 patients with normal stress MPS (summed stress score ≤3) were enrolled. All patients underwent coronary angiography (CAG) and stress/rest 201Tl dynamic SPECT for MBF and MPR calculation. The diagnostic accuracy of both these quantitative values and other clinical risk factors for predicting occult CAD were validated by CAG. MPR was 2.85 in patients with no CAD, 2.47 with 1-, 1.98 with 2-, and 1.76 with 3-vessel CAD. The patient's age, morbidity of diabetes mellitus (DM), chronic kidney disease (CKD), stress MBF, and MPR were significantly associated with the presence of CAD (age, p = 0.02; DM, p = 0.005; CKD, p = 0.005; creatinine level, p = 0.012, stress MBF, p = 0.019, and MPR, p < 0.001). Independent predictors in the multivariate regression analysis were as follows: DM, p = 0.011, CKD, p = 0.028, and MPR, p < 0.001. The combined index was calculated from three independent predictors. Area under the receiver operating characteristic curve was 0.75 for MPR and 0.81 for the combined index. To identify CAD, sensitivity, and specificity for MPR were 77% and 66%, and for the combined index they were 79% and 66%, respectively. Quantification of MPR and MBF using dynamic SPECT with a CZT camera can be useful to identify balanced ischemia caused by occult CAD in patients with normal stress MPS findings. [ABSTRACT FROM AUTHOR]

In this study, we sought to investigate the impact of baseline calibration, which is used in quantitative cardiac MRI perfusion analysis to correct for surface coil inhomogeneity and noise, on myocardial perfusion reserve index (MPRI) and its contribution to previously reported paradoxical low MPRI < 1.0 in patients with unobstructed coronary arteries. Semiquantitative perfusion analysis was performed in 20 patients with unobstructed coronary arteries undergoing stress/rest perfusion CMR and in ten patients undergoing paired rest perfusion CMR. The following baseline calibration settings were compared: (1) baseline division, (2) baseline subtraction and (3) no baseline calibration. In uncalibrated analysis, we observed ~ 20% segmental dispersion of signal intensity (SI)-over-time curves. Both baseline subtraction and baseline division reduced relative dispersion of t0-SI (p < 0.001), but only baseline division corrected for dispersion of peak-SI and maximum upslope also (p < 0.001). In the assessment of perfusion indices, however, baseline division resulted in paradoxical low MPRI (1.01 ± 0.23 vs. 1.63 ± 0.38, p < 0.001) and rest perfusion index (RPI 0.54 ± 0.07 vs. 0.94 ± 0.12, p < 0.001), respectively. This was due to a reversed ratio of blood-pool and myocardial baseline-SI before the second perfusion study caused by circulating contrast agent from the first injection. In conclusion, baseline division reliably corrects for inhomogeneity of the surface coil sensitivity profile facilitating comparisons of regional myocardial perfusion during hyperemia or at rest. However, in the assessment of MPRI, baseline division can lead to paradoxical low results (even MPRI < 1.0 in patients with unobstructed coronary arteries) potentially mimicking severely impaired perfusion reserve. Thus, in the assessment of MPRI we propose to waive baseline calibration. [ABSTRACT FROM AUTHOR]

Women with angina and no obstructive coronary artery disease (CAD) have worse cardiovascular prognosis than asymptomatic women. Limitation in myocardial perfusion caused by coronary microvascular dysfunction (CMD) is one of the proposed mechanisms contributing to the adverse prognosis. The aim of this study was to assess myocardial perfusion in symptomatic women with no obstructive CAD suspected for CMD compared with asymptomatic sex-matched controls using static CT perfusion (CTP). We performed a semi-quantitative assessment of the left ventricular myocardial perfusion and myocardial perfusion reserve (MPR), using static CTP with adenosine provocation, in 105 female patients with angina and no obstructive CAD (< 50% stenosis) and 33 sex-matched controls without a history of angina or ischemic heart disease. Patients were on average 4 years older (p = 0.04) and had a higher burden of cardiovascular risk factors. While global perfusion during rest was comparable between the groups (age-adjusted p = 0.12), global perfusion during hyperemia was significantly reduced in patients compared with controls (163 ± 23 HU vs. 171 ± 25 HU; age-adjusted p = 0.023). The ability to increase myocardial perfusion during adenosine-induced vasodilation was significantly diminished in patients (MPR 148% vs. 158%; age-adjusted p < 0.001). This remained unchanged after adjustment for cardiovascular risk factors (p = 0.008). Women with angina and no obstructive CAD have reduced hyperemic myocardial perfusion and MPR compared with sex-matched controls. Impaired myocardial perfusion may be related to the presence of CMD in some of these women. [ABSTRACT FROM AUTHOR]

Abstract Background Recent studies have shown that quantification of myocardial perfusion (MP) at stress and myocardial perfusion reserve (MPR) offer additional diagnostic and prognostic information compared to qualitative and semi-quantitative assessment of myocardial perfusion distribution in patients with coronary artery disease (CAD). Technical advancements have enabled fully automatic quantification of MP using cardiovascular magnetic resonance (CMR) to be performed in-line in a clinical workflow. The aim of this study was to validate the use of the automated CMR perfusion mapping technique for quantification of MP using 13N–NH3 cardiac positron emission tomography (PET) as the reference method. Methods Twenty-one patients with stable CAD were included in the study. All patients underwent adenosine stress and rest perfusion imaging with 13N–NH3 PET and a dual sequence, single contrast bolus CMR on the same day. Global and regional MP were quantified both at stress and rest using PET and CMR. Results There was good agreement between global MP quantified by PET and CMR both at stress (−0.1 ± 0.5 ml/min/g) and at rest (0 ± 0.2 ml/min/g) with a strong correlation (r = 0.92, p

Competing Interests: Declaration of competing interest Dr. Bourque owns equity in Locus Health and is a consultant for Pfizer and General Electric. Dr. Salerno receives research support from Siemens. The remaining authors have no competing interests to declare.

Aims We evaluated the relationship between epicardial adipose tissue (EAT) and coronary vascular function assessed by rubidium-82 (82Rb) positron emission tomography/computed tomography (PET/CT) in patients with suspected coronary artery disease (CAD). Methods and results The study population included 270 patients with suspected CAD and normal myocardial perfusion at stress–rest 82Rb PET/CT. Coronary artery calcium (CAC) score and EAT volume were measured. Absolute myocardial blood flow (MBF) was computed in mL/min/ from the dynamic rest and stress imaging. Myocardial perfusion reserve (MPR) was defined as the ratio of hyperaemic to baseline MBF and it was considered reduced when <2. MPR was normal in 177 (65%) patients and reduced in 93 (35%). Patients with impaired MPR were older (P  <   0.001) and had higher CAC score values (P  =   0.033), EAT thickness (P  =   0.009), and EAT volume (P  <   0.001). At univariable logistic regression analysis, age, heart rate reserve (HRR), CAC score, EAT thickness, and EAT volume resulted significant predictors of reduced MPR, but only age (P  =   0.002), HRR (P  =   0.021), and EAT volume (P  =   0.043) were independently associated with reduced MPR, at multivariable analysis. In patients with CAC score 0 (n  =   114), a significant relation between EAT volume and MPR (P  =   0.014) was observed, while the relationship was not significant (P  =   0.21) in patients with CAC score >0 (n  =   156). Conclusion In patients with suspected CAD and normal myocardial perfusion, EAT volume predicts hyperaemic MBF and reduced MPR, confirming that visceral pericardium fat may influence coronary vascular function. Thus, EAT evaluation has a potential role in the early identification of coronary vascular dysfunction. [ABSTRACT FROM AUTHOR]

Aims Impaired myocardial perfusion reserve (MPR) may occur earlier than coronary atherosclerosis and it may be an early manifestation of developing coronary artery disease (CAD) in patients with resistant hypertension (RH). We evaluated the relationship between RH and MPR in patients with systemic arterial hypertension after balancing for coronary risk factors. Methods and results We studied 360 subjects without overt CAD and normal myocardial perfusion at stress-rest 82Rb positron emission tomography/computed tomography. To account for differences in baseline characteristics between patients with resistant and controlled hypertension, we created a propensity score-matched cohort considering clinical variables and coronary risk factors. Before matching, patients with RH were significantly older, had higher prevalence of male gender and hypercholesterolaemia, and showed significantly lower global hyperaemic myocardial blood flow (MBF) and MPR compared with those with controlled hypertension, while baseline MBF and coronary artery calcium (CAC) content were similar in both groups. After matching, there were no significant differences in clinical variables and coronary risk factors between patients with resistant and controlled hypertension, but patients with RH still had lower hyperaemic MBF and MPR (both P  <   0.001). At univariable and multivariable linear regression analyses, age, RH, and CAC resulted significant predictors of lower MPR values (all P  <   0.05). Conclusion After balancing clinical characteristic by propensity score analysis, patients with RH had a blunted hyperaemic MBF and MPR compared with patients with controlled hypertension. The identification of impaired MPR could help to identify early structural alterations of the arterial walls in patients with RH. [ABSTRACT FROM AUTHOR]

Summary: Purpose: Combined coronary CT angiography and CT perfusion (CTP) is a novel, non‐invasive, 'one‐stop' diagnostic tool to rule out ischaemia in patients suspected for coronary artery disease (CAD). However, the normal myocardial perfusion pattern by static CTP in humans is poorly described. We aimed to investigate global and regional myocardial perfusion during rest and adenosine‐induced hyperaemia in asymptomatic women without history of coronary heart disease (CHD). Methods: Using a 320‐row CT scanner with a static protocol, semi‐quantitative assessment of rest and stress CTP was performed in 34 asymptomatic middle‐aged women without obstructive CAD (<50% stenosis) or history of CHD, and with normal exercise stress test and left ventricular (LV) function. Using a 16‐segment model, we assessed global and regional values of LV myocardial perfusion reserve (MPR) and transmural perfusion ratio (TPR). Results: Mean±SD age was 56 ± 13 years. Resting and hyperaemic myocardial perfusion was heterogeneously distributed throughout the LV myocardium. During hyperaemia, global MPR increased by median (IQR) 158% (144–176) with the highest increase in the right coronary artery territory (171%; P<0.02). Rest and stress segmental TPR values ranged between 0.93‐1.26 and 0.99‐1.13, respectively, with the lowest values detected in the inferoseptal segments. No differences in perfusion parameters were found between participants with normal epicardial arteries and participants with non‐significant epicardial atheromatosis (all P>0.05). Global perfusion parameters were not associated with age or menopausal status (all P>0.05). Conclusions: This descriptive study presents data on global and regional myocardial perfusion in a cohort of healthy middle‐aged women. [ABSTRACT FROM AUTHOR]

Purpose: We evaluated the feasibility of dynamic stress 201Tl/rest 99mTc-tetrofosmin SPECT imaging using a cardiac camera equipped with cadmium-zinc-telluride detectors for the quantification of myocardial perfusion reserve (MPR).Methods: Subjects with stable known or suspected coronary artery disease (CAD) who had undergone or were scheduled to undergo fractional flow reserve (FFR) measurement were prospectively enrolled. Dynamic stress 201Tl/rest 99mTc-tetrofosmin SPECT imaging was performed using a dedicated multiple pinhole SPECT camera with cadmium-zinc-telluride detectors. MPR was derived using Corridor4DM software.Results: A total of 34 subjects were enrolled (25 men and 9 women; mean age 60.4 years). FFR was measured in 65 coronary arteries with intermediate lesions. The average global MPR was 2.58 ± 1.03. Global MPR was associated with the extent of CAD (P = 0.028) and global summed stress score (r = −0.60, P < 0.001). Regional MPR showed a significant correlation with diameter stenosis (r = −0.57, P < 0.001), minimum lumen diameter (r = 0.50, P < 0.001), summed stress score (r = −0.52, P < 0.001) and FFR (r = 0.52, P < 0.001). The area under the receiver operating characteristic curve of MPR for the diagnosis of functionally significant stenosis (FFR ≤0.8) was 0.79 (P < 0.001). The sensitivity and specificity of regional MPR were 67% and 83%, respectively, using a cut-off value of 2.0.Conclusion: Dynamic stress 201Tl/rest 99mTc-tetrofosmin SPECT imaging and quantification of MPR is feasible in patients with stable CAD. The preliminary results of this study in a small number of patients require confirmation in a larger cohort to determine their implications for bolstering the role of SPECT imaging in the diagnosis and risk prediction of CAD. [ABSTRACT FROM AUTHOR]

Background: Cardiac PET quantifies stress myocardial blood flow (MBF) and perfusion reserve (MPR), while ECG-gated datasets can measure components of ventricular function simultaneously. Stress MBF seems to outperform MPR in the detection of significant CAD. However, it is uncertain which perfusion measurement is more related to ventricular function. We hypothesized that stress MBF correlates with ventricular function better than MPR in patients studied for suspected myocardial ischemia.Methods: We studied 248 patients referred to a rest and adenosine-stress Nitrogen-13 ammonia PET. We performed a multivariate analysis using systolic function (left ventricular ejection fraction, LVEF), diastolic function (mean filling rate in diastole, MFR/3), and synchrony (Entropy) as the outcome variables, and stress MBF, MPR, and relevant covariates as the predictors. Secondarily, we repeated the analysis for the subgroup of patients with and without a previous myocardial infarction (MI).Results: 166 male and 82 female patients (mean age 63 ± 11 and 67 ± 11 year, respectively) were included. 60% of the patients presented hypertension, 57% dyslipidemia, 21% type 2 diabetes mellitus, 45% smoking, and 34.7% a previous MI. Mean stress MBF was 1.99 ± 0.75 mL/g/min, MPR = 2.55 ± 0.89, LVEF = 61.6 ± 15%, MFR/3 = 1.12 ± 0.38 EDV/s, and Entropy = 45.6 ± 11.3%. There was a significant correlation between stress MBF (P < .001) and ventricular function. This was stronger than the one for MPR (P = .063). Sex, age, diabetes, and extent of previous MI were also significant predictors. Results were similar for the analyses of the 2 subgroups.Conclusion: Stress MBF is better correlated with ventricular function than MPR, as evaluated by Nitrogen-13 ammonia PET, independently from other relevant cardiovascular risk factors and clinical covariates. This relationship between coronary vasodilatory capacity and ventricular function is sustained across groups with and without a previous MI. [ABSTRACT FROM AUTHOR]

Background: Preliminary semi-quantitative cardiovascular magnetic resonance (CMR) perfusion studies have demonstrated reduced myocardial perfusion reserve (MPR) in patients with angina and risk factors for microvascular disease (MVD), however fully quantitative CMR has not been studied. The purpose of this study is to evaluate whether fully quantitative CMR identifies reduced MPR in this population, and to investigate the relationship between epicardial atherosclerosis, left ventricular hypertrophy (LVH), extracellular volume (ECV), and perfusion. Methods: Forty-six patients with typical angina and risk factors for MVD (females, or males with diabetes or metabolic syndrome) who had no obstructive coronary artery disease by coronary angiography and 20 healthy control subjects underwent regadenoson stress CMR perfusion imaging using a dual-sequence quantitative spiral pulse sequence to quantify MPR. Subjects also underwent T1 mapping to quantify ECV, and computed tomographic (CT) coronary calcium scoring to assess atherosclerosis burden. Results: In patients with risk factors for MVD, both MPR (2.21 [1.95,2.69] vs. 2.93 [2.763.19], p < 0.001) and stress myocardial perfusion (2.65 ± 0.62 ml/min/g, vs. 3.17 ± 0.49 ml/min/g p < 0.002) were reduced as compared to controls. These differences remained after adjusting for age, left ventricular (LV) mass, body mass index (BMI), and gender. There were no differences in native T1 or ECV between subjects and controls. Conclusions: Stress myocardial perfusion and MPR as measured by fully quantitative CMR perfusion imaging are reduced in subjects with risk factors for MVD with no obstructive CAD as compared to healthy controls. Neither myocardial hypertrophy nor fibrosis accounts for these differences. [ABSTRACT FROM AUTHOR]

Background Chronic kidney disease (CKD) is an independent risk factor for cardiovascular disorders. The aim of this study was to examine whether the quantitatively measured myocardial blood flow (MBF) or myocardial perfusion reserve (MPR), calculated by dynamic single photon emission computed tomography (SPECT) analysis using a cardiac cadmium zinc telluride (CZT) gamma camera, was related to renal dysfunction in patients with normal myocardial perfusion imaging (MPI) findings. Methods The study population consisted of 46 patients with CKD and 46 individuals without CKD (controls). Their MPR index was quantitatively measured using adenosine MPI with a cardiac CZT gamma camera. All assessments were with a single tissue compartment kinetic model. The K1 value was calculated on stress and at-rest images. To obtain the MPR index we divided K1 stress-by K1 at-rest values. Results The at-rest K1 value was significantly higher and the MPR index was significantly lower in patients with CKD than those without CKD [CKD vs. controls: at-rest K1 value, 0.21 (0.17–0.25) vs. 0.19 (0.16–0.22), p = 0.040; MPR index, 1.86 (1.69–2.22) vs. 2.19 (1.93–2.41), p < 0.001]. The stress K1 values were not significantly different. Conclusion The MPR index is significantly lower in CKD patients; this is considered as being mainly due to an increase in the at-rest K1 value. [ABSTRACT FROM AUTHOR]