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Objective: Patients with Takotsubo syndrome (TTS) present an acute microvascular dysfunction that leads to an impaired myocardial perfusion and, in more severe forms, an impaired epicardial flow. However, clinical relevance of a delayed coronary flow, the coronary slow flow (CSF), has never been investigated. We studied the prognostic value of CSF occurring in the acute phase of TTS., Methods: This cohort study prospectively evaluated patients with a diagnosis of TTS. CSF was defined as angiographically non-obstructive coronary arteries with thrombolysis in myocardial infarction-2 flow. The incidence of overall mortality and major adverse cardiovascular events (MACEs), defined as the composite of TTS recurrence, cardiac rehospitalisation, cerebrovascular events and mortality, was assessed at follow-up., Results: We enrolled 101 patients (mean age 71.0±11.1 years, 86 (85.1%) female); CSF occurred in 18 (17.8%) patients. At admission, patients with CSF presented more frequently with Killip class III/IV, moderate-to-severe left ventricle systolic dysfunction and right ventricle dysfunction. During the index admission, patients with CSF had a higher rate of intrahospital complications (12 (66.7%) vs 28 (33.7%), p=0.01). At long-term follow-up, patients with CSF had a significantly higher occurrence of overall mortality (9 (50%) vs 19 (22.9%), p=0.011), mainly due to non-cardiac causes (89.3%), and a higher rate of MACE (10 (55.5%) vs 27 (32.5%), p=0.06). At multivariable Cox regression, CSF was independently associated with death from any causes., Conclusions: Patients with TTS presenting with CSF have a worse clinical presentation with a higher rate of intrahospital complications and a poor long-term clinical outcome., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

Objectives: To angiographically assess myocardial perfusion in patients with Tako-Tsubo syndrome (TTS) in comparison with control individuals and patients with ST-elevation myocardial infarction (STEMI)., Background: Coronary microvascular dysfunction has been proposed as the pathophysiological mechanism underlying TTS., Methods: We retrospectively selected consecutive TTS patients showing typical left ventricular (LV) apical dysfunction admitted to our Department in the period 2007-2011 (n=25). We also enrolled an age and gender-matched control group showing normal coronary arteries (CTR, n=25), patients with STEMI undergoing primary percutaneous intervention with myocardial reperfusion (SR, n=25) or microvascular obstruction (SMVO, n=25). TIMI flow, TIMI frame count (TFC) and both qualitative and quantitative myocardial blush grade in LV apex were assessed. Specifically, myocardial perfusion was quantitatively evaluated using 'Quantitative Blush Evaluator' (QuBE), an open source software previously validated in the setting of STEMI., Results: In TTS, TIMI flow on the LAD was significantly lower and TFC significantly higher compared to CTR and SR (p=0.008 for both), while it did not significantly differ compared to SMVO (p=0.06). In TTS, MBG was significantly lower than that in CTR and SR (p=0.001 for both), while it was significantly higher than that in SMVO (p<0.001). In TTS, QuBE score was significantly lower than that in CTR and SR (p=0.001 for both) and higher than in SMVO (p=0.02)., Conclusions: Our data indicate that myocardial perfusion assessed during angiography is more impaired in patients with TTS than in patients with STEMI exhibiting myocardial reperfusion, while it is less impaired than in patients with STEMI exhibiting MVO., (© 2013.)

Aims: The effects of the reopening of a coronary total occlusion (CoTO) on microvascular perfusion in subacute or chronic coronary syndromes are actually unclear. We aimed at evaluating the microvascular perfusion pattern by myocardial contrast echocardiography (MCE), in addition to contractile function, before and after CoTO reopening., Methods: Twenty four patients with subacute and chronic coronary syndromes and CoTO datable >7 days underwent evaluation of microvascular perfusion and left ventricular (LV) function by MCE (Acuson Sequoia, with Sonovue, Bracco) before the reopening of the CoTO and at 9 ± 3 months of follow-up. Microvascular perfusion was semi-quantitatively assessed by the contrast score index (CSI), whereas the endocardial length of the perfusion defect [contrast defect length (CDL)], measured in three apical views and averaged, was expressed as a percentage of the total LV endocardial border. The wall motion score index (WMSI), LV volumes, and ejection fraction were also calculated., Results: At baseline, a mild impairment of LV contractile function was observed, which corresponded to a similar impairment of the coronary microvascular perfusion in the overall study population. At follow-up, a significant reduction of CDL% [8.23 (0-19.63) vs. 0 (0-3.68), P = 0.005], improvement of the CSI (1.41 ± 0.29 vs. 1.12 ± 0.17, P = 0.001) and the WMSI (1.73 ± 0.41 vs. 1.33 ± 0.34, P = 0.0004), and increase in the ejection fraction (47.48% ± 8.66 vs. 55.60% ± 8.29, P = 0.0001) were found., Conclusion: Reopening of a CoTO in patients with clinical indications to myocardial revascularization is associated with the improvement of coronary microvascular perfusion and the recovery of contractile function.

A growing amount of data is increasingly showing the relevance of coronary microvascular dysfunction (CMVD) in several clinical contexts. This article reviews techniques and clinical investigations of the main noninvasive and invasive methods proposed to study coronary microcirculation and to identify CMVD in the presence of normal coronary arteries, also trying to provide indications for their application in clinical practice.

Aims: The anatomical correlates of perfusion defect (PD) at myocardial contrast echocardiography (MCE) in the subacute phase of ST-elevation myocardial infarction (STEMI) are currently unknown. The study aimed at assessing whether, in the subacute phase of STEMI, within MCE PD microvessels are anatomically damaged or if some vasodilation can be still elicited and if the PD correlates with the extent of myocardial necrosis., Methods and Results: Twenty-two post-percutaneous coronary intervention (PCI) patients underwent MCE 7 ± 1 days after STEMI, at baseline and after adenosine (ADN) administration. An area of completely non-opacified myocardium, corresponding to the area of the PD, was quantitated by planimetry. The area of the PD on MCE was compared with biochemical and imaging measures of myocardial necrosis: cardiac Troponin T peak (cTnT peak) and hyperenhanced area at gadolinium-enhanced cardiac magnetic resonance (Gd-CMR), respectively. After vasodilator stimulus, the area of the PD remained significantly unchanged when compared with the baseline value (P = 0.09 vs. baseline). The MCE index correlated at baseline with cTnT peak and Gd-CMR assessments of myocardial necrosis (P < 0.001). Also after ADN infusion, correlations between PD and extent of myocardial necrosis were similar to that assessed at baseline., Conclusion: When assessed in the subacute phase of STEMI, the extent of the PD on MCE represents an area of both myocardial and microvascular necrosis.

The term "coronary instability" commonly refers to the sequence of events that lead from plaque erosion or rupture to the occurrence of acute coronary syndromes (ACS). However, evidence indicates that coronary microvascular dysfunction plays a relevant pathophysiologic and prognostic role in the setting of ACS, both in ST-segment elevation myocardial infarction and in non-ST-segment elevation ACS. Our group have recently demonstrated that Tako-Tsubo syndrome, which clinically mimics ACS, is sustained by a common pathophysiologic mechanism represented by reversible coronary microvascular dysfunction. Given this evidence, we propose a reappraisal of the concept of coronary instability, extending this notion from the dramatic event represented by plaque erosion or rupture to a more diffuse process that can acutely affect each segment of the coronary circulation., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Background: After ST-elevation myocardial infarction (STEMI), microvascular obstruction (MVO) can be assessed using semiquantitative angiographic "blush" scores subject to interoperator variability. Quantitative Blush Evaluator (QuBE) is a free computer-calculated algorithm that evaluates myocardial blush on a continuous scale with improved reproducibility. We aimed to compare QuBE with cardiovascular magnetic resonance (CMR) in detecting MVO and its severity., Methods: Fifty-two STEMI treated with successful primary percutaneous coronary intervention were enrolled. Quantitative Blush Evaluator and electrocardiographic sum ST-segment resolution were blindly calculated. All patients underwent CMR 4 to 7 days after STEMI for assessment of infarct size (IS), myocardial salvage index, MVO (both as first-pass MVO and delayed-enhancement MVO [DE-MVO]), and presence of intramyocardial hemorrhage on T2-weighted sequences., Results: Quantitative Blush Evaluator values were inversely related to IS (R = -0.4, P = .008), DE-MVO (R = -0.7, P < .001), and first-pass MVO (R = -0.4, P = .002) and positively related to myocardial salvage index (R = 0.4, P = .007). Moreover, patients with intramyocardial hemorrhage had significantly lower QuBE values (3.9, 3.5-8.0 vs 12.2, 8.2-16.0, P = .001) than those without. At receiver operating characteristic curve analysis, QuBE accounted for an area under the curve of 0.88 (95% CI 0.7-0.9, P = .001) for both DE-MVO and hemorrhage detection and performed significantly better than ST resolution., Conclusions: Quantitative Blush Evaluator score correlates with IS and microvascular dysfunction by CMR and can be considered as an accurate tool for the assessment of MVO in clinical practice. Quantitative Blush Evaluator is a useful quantitative angiographic technique for the assessment of myocardial reperfusion after STEMI., (Copyright © 2011 Mosby, Inc. All rights reserved.)

Assessment of myocardial "blush" by either Myocardial Blush Grade or TIMI Myocardial Perfusion Grade, is the angiographic method currently preferred to confirm myocardial tissue-level perfusion after primary percutaneous intervention. This review focuses on the utility of angiographic "blush" as a simple, widely available, and virtually costless technique for the immediate diagnosis of microvascular impairment at the time of acute catheterization. We comprehensively outline the available evidence behind the "blush," its use in clinical practice, and draw comparisons with other new technologies for assessment of microvascular integrity., (Copyright © 2010 Mosby, Inc. All rights reserved.)

Objectives: We sought to evaluate the value of the extent of microvascular damage as assessed with myocardial contrast echocardiography (MCE) in the prediction of left ventricular (LV) remodeling after ST-segment elevation myocardial infarction (STEMI) as compared with established clinical and angiographic parameters of reperfusion., Background: Early identification of post-percutaneous coronary intervention microvascular dysfunction may help in tailoring appropriate pharmacological interventions in high-risk patients. The ideal method to establish effective microvascular reperfusion after percutaneous coronary intervention remains to be determined., Methods: A total of 110 patients with first successfully reperfused STEMI were enrolled in the AMICI (Acute Myocardial Infarction Contrast Imaging) multicenter study. After reperfusion, peak creatine kinase, ST-segment reduction, and Thrombolysis In Myocardial Infarction (TIMI) and myocardial blush grade were calculated. We evaluated perfusion defects with MCE by using continuous infusion of Sonovue (Bracco, Milan, Italy) in real-time imaging. The endocardial length of contrast defect (CD) on day 1 after reperfusion was calculated. Wall motion score index, the extent of wall motion abnormalities, LV end-diastolic volume, and ejection fraction after reperfusion and at follow-up also were calculated., Results: Of 110 patients, 25% evolved in LV remodeling and 75% did not. Although peak creatine kinase, ST-segment reduction >70%, and myocardial blush grade were not different between groups, in patients exhibiting LV remodeling, TIMI flow grade 3 was less frequent (p < 0.001), wall motion score index was greater (p < 0.001), and CD was greater (p < 0.001). At multivariate analysis, only TIMI flow grade <3 and CD with a cutoff of >25% were independently associated with LV remodeling. Among patients with TIMI flow grade 3, CD was the only independent variable associated with LV remodeling., Conclusions: Among patients with TIMI flow grade 3, the extent of microvascular damage, detected and quantitated by MCE, is the most powerful independent predictor of LV remodeling after STEMI as compared with persistent ST-segment elevation and myocardial blush grade.

Objectives: The purpose of this study was to investigate whether a direct relation can be demonstrated between myocardial perfusion defects detected during dobutamine stress test (DST) by cardiovascular magnetic resonance (CMR) and impairment of coronary microvascular dilatory function in patients with cardiac syndrome X (CSX)., Background: Despite the fact that coronary microvascular dysfunction has been shown in most patients with CSX, the ischemic origin of CSX remains debated. No previous study assessed whether a strict relation exists between abnormalities in myocardial perfusion and coronary microvascular dysfunction in CSX patients., Methods: Eighteen CSX patients (mean age 58 +/- 7 years, 7 men) and 10 healthy control subjects (mean age 54 +/- 8 years, 4 men) underwent myocardial perfusion study by gadolinium-enhanced CMR at rest and at peak DST (maximal dose 40 microg/kg/min). Coronary flow response (CFR) to adenosine (140 microg/kg/min in 90 s) in the left anterior descending (LAD) coronary artery was assessed by high-resolution transthoracic echo-Doppler and expressed as the ratio between coronary flow velocity at peak adenosine and at rest., Results: At peak DST, reversible perfusion defects on CMR were found in 10 CSX patients (56%) but in none of the control subjects (p = 0.004). The CFR to adenosine in the LAD coronary artery was lower in CSX patients than in control subjects (2.03 +/- 0.63 vs. 3.29 +/- 1.0, p = 0.0004). The CSX patients with DST-induced myocardial perfusion defects in the LAD territory on CMR had a lower CFR to adenosine compared with those without perfusion defects in the LAD territory (1.69 +/- 0.5 vs. 2.31 +/- 0.6, p = 0.01). A significant correlation was found in CSX patients between CFR to adenosine and a DST perfusion defect score on CMR in the LAD territory (r = -0.45, p = 0.019)., Conclusions: Our data concurrently show DST-induced myocardial perfusion defects on CMR and reduced CFR in the LAD coronary artery territory in CSX patients, thus giving strong evidence that a dysfunction of coronary microcirculation resulting in myocardial perfusion abnormalities is present in these patients.

Data on coronary flow reserve (CFR) in patients with syndrome X are still controversial. Further, noninvasive evaluation of epicardial and microvascular flow reserves in these patients has never been performed. In 17 patients with syndrome X and in 17 age- and gender-matched control subjects, CFR in the mid left anterior descending coronary artery (LAD) was evaluated by transthoracic color and pulse-wave Doppler using a 7-mHz probe (Sequoia, Siemens). Peak diastolic LAD flow was calculated at rest and at peak adenosine (140 microg/kg/min intravenously in 90 seconds). Myocardial contrast echocardiography (MCE) was performed at rest and during adenosine use by real-time cadence pulse sequencing and intravenous SonoVue (Bracco; 5 ml at 1 ml/min) and microvascular blood volume (A), velocity (beta), and flow (Axbeta) by replenishing curves (y = A[1 - e(betat)]). CFR was measured by Doppler echocardiography as an adenosine/rest velocity ratio and by MCE as a microvascular volume, velocity, and flow adenosine/rest ratio. Compared with controls, patients with syndrome X demonstrated lower LAD CFR and velocity and flow microvascular flow reserves (p <0.01, <0.005, and <0.005, respectively). In patients with syndrome X, those with angina and ST-segment depression during adenosine testing had even lower LAD CFR and velocity and flow microvascular flow reserves compared with those with no symptoms (p <0.0001, <0.0001, and <0.005, respectively). LAD CFR demonstrated a significant linear correlation with velocity microvascular flow reserve (r = 0.92, p <0.0001) and flow microvascular flow reserve (r = 0.77, p <0.0001). In conclusion, CFR in the LAD, successfully evaluated by transthoracic Doppler echocardiography and MCE, is significantly decreased in patients with syndrome X and even more in those with angina pectoris and ST-segment depression during adenosine testing. Thus, noninvasive evaluation of CFR by echocardiography is feasible and provides information on the severity of microvascular impairment.

The burden of aortic stenosis is increasing steadily and, despite major advances in diagnosis and management, surgical valve replacement is still the only effective treatment. Most recently, experimental studies in animals and clinical studies in humans have shown that myocardial hypertrophy, microcirculatory dysfunction and cardiomyocyte apoptosis are among the central pathophysiologic mechanisms involved in the natural history of aortic stenosis, i.e. the passage from a compensated and hypertrophic heart to a dysfunctional heart prone to ischemia, arrhythmia and pump failure. This updated review emphasizes the promises of these new research avenues as well as their potential therapeutic applications.

Background: Information on the accuracy of both magnetic resonance imaging (MRI) and myocardial contrast echocardiography (MCE) for the identification of perfusion defects in patients with acute myocardial infarction is limited. We evaluated the accuracy of MRI and MCE, using Single Photon Emission Computed Tomography (SPECT) imaging as reference technique., Methods: Fourteen consecutive patients underwent MCE, MRI and 99mTc-MIBI SPECT after acute myocardial infarction to assess myocardial perfusion. MCE was performed by Harmonic Power Angio Mode, with end-systolic triggering 1:4, using i.v. injection of Levovist. First-pass and delayed enhancement MRI was obtained after i.v administration of Gadolinium-DTPA. At MCE, homogeneous perfusion was considered as normal and absent or "patchy" perfusion as abnormal. At MRI, homogenous contrast enhancement was defined as normal whereas hypoenhancement at first-pass followed by hyperenhancement or persisting hypoenhancement in delayed images was defined as abnormal., Results: At MCE 153 (68%) of segments were suitable for analysis compared to 220 (98%) segments at MRI (p<0.001). Sensitivity, specificity and accuracy of MCE for segmental perfusion defects in these 153 segments were 83, 73 and 77%, respectively. Sensitivity, specificity and accuracy of MRI were 63, 82, and 77%, respectively. MCE and MRI showed a moderate agreement with SPECT (k: 0.52 and 0.46, respectively). The agreement between MCE and MRI was better (k: 0.67) that the one of each technique with SPECT., Conclusion: MCE and MRI may be clinically useful in the assessment of perfusion defects in patients with acute myocardial infarction, even thought MCE imaging may be difficult to obtain in a considerable proportion of segments when the Intermittent Harmonic Angio Mode is used.

Objective: To test the hypothesis that impaired coronary and myocardial blood flow are linked with increased myocyte apoptosis, thus establishing a link between pressure overload and left ventricular (LV) remodelling., Methods and Results: Peak diastolic coronary blood flow velocity (CBFV) was evaluated at transthoracic Doppler echocardiography, and signal intensity (SI) and the rate of SI rise (beta) were measured at myocardial contrast echocardiography in 11 patients with severe aortic stenosis and LV hypertrophy. In the same patients, biopsies were obtained from the anterolateral LV free wall during surgery and analysed for cardiomyocyte apoptosis. LV mass corrected CBFV (CBFVI) was significantly lower in patients than in controls (median 0.100 cm.g/s (interquartile range 0.07-0.115) v 0.130 cm.g/s (0.130-0.160), p = 0.002). Similarly, SI*beta was significantly lower in patients than in controls (11 1/s (8-66) v 83 1/s (73-95), p = 0.001). Apoptotic rate was increased in aortic stenosis more than 100-fold versus controls (1.2% (0.8-1.4) v 0.01% (0.01-0.01), p < 0.001) and inversely correlated with lower CBFVI and SI*beta (r = -0.77, p = 0.001 for both)., Conclusions: Patients with severe aortic stenosis and LV hypertrophy have impaired myocardial perfusion, which is associated with enhanced cardiomyocyte apoptosis. Impaired myocardial perfusion and the ensuing oxygen demand-supply imbalance may, at least partially, be responsible for increased apoptosis and possible transition to heart failure, thus establishing a link between pressure overload, LV remodelling, and heart failure.

Previously defined as the failure to achieve uniform intramyocardial reperfusion after prolonged but reversible coronary occlusion, only recently has no-reflow phenomenon been characterized as a heterogeneous clinical condition. In fact, in about half of post-infarct patients that show no-reflow after 24 hours from coronary recanalization by either thrombolysis or PTCA, no-reflow phenomenon is spontaneously reversible. Reversible no-reflow is associated with favorable left ventricular remodeling even in the absence of significant improvement in regional contractile function. Thus, it may be a clinical marker of yet unknown mechanisms, which may favorably affect myocardial response to necrosis. Based on the pathogenesis and on the time-course of no-reflow, the phenomenon may be associated with lack of patency or with loss of anatomic integrity of microvessels, with the former being potentially reversible while the latter associated with definitive tissue damage. As a consequence, possible therapeutic strategies of no-reflow have to be designed according to not only the main target [microvessel patency or integrity], but also taking into account the timing of development of the damage. This "mini review" is focused on recent advances on the pathogenesis and clinical presentation on no-reflow. These data will give the opportunity to formulate novel interpretation and classification of the phenomenon and consequently, to propose adequate therapeutic strategies.

Objective: To identify in humans the temporal patterns of no reflow and their functional implications., Methods: 24 patients with first acute myocardial infarction and successful coronary recanalisation by recombinant tissue-type plasminogen activator (n = 15) or primary percutaneous transluminal coronary angioplasty (n = 9) were studied by myocardial contrast echocardiography within 24 hours of recanalisation and at one month's follow up. Myocardial contrast echocardiography was performed by intermittent harmonic power Doppler and intravenous Levovist. The regional contrast score index (CSI) was calculated within dysfunctioning myocardium. Videointensity was measured (dB) within risk and control areas and their ratio was calculated., Results: In 8 patients reflow was observed at 24 hours and persisted at one month. Conversely in 16 patients areas of no reflow were detectable at 24 hours. At one month, no reflow was spontaneously reversible in 9 patients (mean (SD) CSI and videointensity ratio improved from 2.5 (0.5) to 1.4 (0.6) and from 0.6 (0.1) to 0.7 (0.1), respectively; p < 0.05) and was sustained in the remaining 7 patients (CSI and videointensity ratio remained unchanged from 2.6 (0.6) to 2.6 (0.5) and from 0.5 (0.2) to 0.5 (0.2), respectively; NS). Left ventricular function improved significantly in patients with reflow and reversible no reflow. Volumes were enlarged only in patients with sustained no reflow., Conclusions: No reflow detected at 24 hours may be sustained or spontaneously reversible at one month. Such reversibility of the phenomenon is associated with preserved left ventricular volumes and function. Clarification of the mechanisms of delayed reversibility may lead to tailored treatment of no reflow even in the subacute phase of myocardial infarction.

Background: The purpose of this study was to verify whether endothelin A-antagonist administration at the time of coronary reperfusion preserves postischemic microvasculature and whether myocardial contrast echo (MCE) is able to detect pharmacologically induced changes in microvascular reflow., Methods and Results: Twenty dogs underwent 90 minutes of LAD occlusion (OCC) followed by 180 minutes of reperfusion (RP). Five minutes before LAD reopening, an intravenous bolus (5 mg/kg) of LU 135252 was given in 10 dogs and vehicle in the remaining 10. At baseline (BSL), OCC, and 90 and 180 minutes of RP, microvascular flow (BF) was assessed by microspheres, and MCE was performed with intravenous echo contrast. MCE videointensity and BF were expressed as risk area/control ratio. Myocardial thickness of the risk area was calculated by 2D echo. No differences in BF between the 2 groups were observed at BSL, OCC, and 90 minutes of RP. At 180 minutes of RP, BF was decreased in controls (70+/-7.4% of BSL; P:<0.005 versus BSL) and preserved in LU 135252-treated animals (89+/-4% of BSL; P=NS versus BSL; P<0.05 versus controls). Videointensity at MCE closely followed the changes in BF observed in both groups throughout the protocol. Myocardial thickness at 180 minutes of RP increased to 138.6+/-9.9% of BSL in controls and remained at 108.9+/-7.4% of BSL in treated dogs (P<0.05)., Conclusions: Endothelin A-antagonist treatment at the time of reperfusion significantly limited the progressive decrease in postischemic microvascular reflow and the increase in myocardial thickness. MCE allowed a reliable evaluation of pharmacologically induced changes in microvascular flow.

During myocardial ischemia produced by coronary occlusion, coronary microvessels and cardiac myocytes undergo progressive functional and structural changes. The prompt reopening of the epicardial vessel is the main therapeutic strategy to limit the vascular and cellular damage. However, the full benefit of reperfusion can be limited by progressive microvascular obstruction and cell death occurring after the reestablishment of flow. During ischemia-reperfusion, preservation of the integrity of the coronary microvasculature is a fundamental prerequisite to ensuring myocardial viability. Therefore, therapeutic approaches should be developed to prevent and treat microvascular impairment resulting from ischemia-reperfusion. Also, given the importance of the assessment and treatment of post-reperfusion disorders of coronary microvasculature, a diagnostic tool able to evaluate the structural and functional status of the microcirculation in vivo is needed. Myocardial contrast echocardiography has been demonstrated to be extremely useful in this setting. In this review, the anatomic and functional characteristics of the coronary microcirculation are described during normal conditions, as well as in the presence of ischemia-reperfusion injury. The role of myocardial contrast echocardiography in the assessment of microvascular dysfunction and specific potential therapeutic approaches to the treatment of microvascular damage during ischemia and after reperfusion are also discussed.

Background: Dynamic changes of myocardial blood flow have been observed after reperfusion of an occluded coronary artery. MCE performed by intracoronary contrast injection can provide an estimate of microvascular flow. We hypothesized that MCE performed using intravenous infusion of a new generation contrast agent and electrocardiogram-gated harmonic imaging would be able to assess serial changes of microvascular perfusion., Objective: To study the potential of myocardial contrast echocardiography (MCE) to assess serial changes of microvascular flow during ischemia-reperfusion., Methods: Sixteen dogs underwent 90 or 180 min of left anterior descending coronary occlusion, followed by 180 min of reperfusion. Regional blood flow (RBF) was measured with fluorescent microspheres at baseline, during coronary occlusion, and at 5, 30, 90, and 180 min during reperfusion. At the same time points, MCE was performed with intravenous infusion of AF0150 (4 mg/min). Gated end-systolic images in short axis were acquired in harmonic mode and digitized on-line. Background-subtracted videointensity measured from MCE and RBF obtained from fluorescent microspheres were calculated for the risk area and for a control area, and were expressed as the ratio of the two areas., Results: After initial hyperemia, a progressive reduction in flow was observed during reperfusion. MCE correctly detected the time course of changes in flow during occlusion-reperfusion. Videointensity ratio significantly correlated with RBF data (r=0.79; p < 0.0001)., Conclusions: The progressive reduction in blood flow occurring within the postischemic microcirculation was accurately detected by MCE. This approach has potential application in the evaluation and management of postischemic reperfusion in humans.

Aims: The study was set up to evaluate the functional role of post-infarct preserved microvascular integrity. Low dose dobutamine echocardiography and myocardial contrast echocardiography were used to study patients before hospital discharge who had suffered a recent myocardial infarction and had a patent infarct-related artery (TIMI flow grade 3)., Method: In the dysfunctioning infarct area, the wall motion score index was calculated at baseline, during the dobutamine infusion and at the 3 month follow-up echocardiogram; contrast echocardiography was performed at the time of coronary angiography, before hospital discharge., Results: In patients with more than 50% of the dysfunctioning infarct area opacified at contrast echocardiography (group A), regional wall motion score index decreased, compared to baseline, during the dobutamine infusion (1.97 +/- 0.78 vs 2.5 +/- 0.35 at baseline; P < 0.001) and at follow-up echocardiography (1.83 +/- 0.63 vs 2.5 +/- 0.35 at baseline; P < 0.001). In patients with less extensive microvascular integrity as revealed by contrast echocardiography (group B), regional wall motion score index did not decrease from baseline during either the dobutamine infusion (2.73 +/- 0.21 vs 2.81 +/- 0.20 at baseline; P = ns), or at follow-up (2.81 +/- 0.20 vs 2.81 +/- 0.20 at baseline; P = ns)., Conclusion: In patients with post-infarct dysfunctioning myocardium but a patent infarct-related artery, microvascular integrity, as assessed by myocardial contrast echocardiography, is an indicator of myocardial viability in terms of preserved contractile reserve, as demonstrated by dobutamine infusion and functional recovery at follow-up.

The purpose of this study was to evaluate, in postinfarction dysfunctioning myocardium, the relative potential of myocardial contrast and low-dose dobutamine echocardiography in detecting myocardial viability, and the relation between microvascular integrity, contractile reserve, and functional recovery at follow-up. Twenty-four patients with recent myocardial infarction were studied before hospital discharge with low-dose dobutamine and myocardial contrast echocardiography. In the dysfunctioning infarct area, wall motion score index was calculated at baseline, during low-dose dobutamine, and at 3-month follow-up. Revascularization of the infarct-related artery was performed if clinically indicated. Eighteen patients (group A) had myocardial enhancement of the dysfunctioning infarct area at myocardial contrast echocardiography of >50%, whereas the remaining patients (group B) had an increase of < or = 50%. Wall motion score index was similar at baseline in groups A and B (2.6 +/- 0.4 and 2.8 +/- 0.2; p = NS), but it improved during low-dose dobutamine and at follow-up only in group A (1.9 +/- 0.9 and 1.9 +/- 0.7, respectively; p <0.001 vs baseline). In group B, wall motion score index was 2.7 +/- 0.4 with low-dose dobutamine and 2.8 +/- 0.2 at follow-up (p = NS vs rest). In identifying viable myocardial segments, myocardial contrast echo had 100% sensitivity and 46% specificity, whereas low-dose dobutamine echo had 71% sensitivity and 88% specificity. Thus, microvascular integrity after acute myocardial infarction is a fundamental prerequisite for ensuring myocardial contractile reserve and regional functional recovery. Myocardial contrast and low-dose dobutamine echocardiography have different, but complementary, diagnostic characteristics in detecting myocardial viability.