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Background and Aims A routine invasive strategy is recommended in the management of higher risk patients with non-ST-elevation acute coronary syndromes (NSTE-ACSs). However, patients with previous coronary artery bypass graft (CABG) surgery were excluded from key trials that informed these guidelines. Thus, the benefit of a routine invasive strategy is less certain in this specific subgroup. Methods A systematic review and meta-analysis of randomized controlled trials (RCTs) was conducted. A comprehensive search was performed of PubMed, EMBASE, Cochrane, and ClinicalTrials.gov. Eligible studies were RCTs of routine invasive vs. a conservative or selective invasive strategy in patients presenting with NSTE-ACS that included patients with previous CABG. Summary data were collected from the authors of each trial if not previously published. Outcomes assessed were all-cause mortality, cardiac mortality, myocardial infarction, and cardiac-related hospitalization. Using a random-effects model, risk ratios (RRs) with 95% confidence intervals (CIs) were calculated. Results Summary data were obtained from 11 RCTs, including previously unpublished subgroup outcomes of nine trials, comprising 897 patients with previous CABG (477 routine invasive, 420 conservative/selective invasive) followed up for a weighted mean of 2.0 (range 0.5–10) years. A routine invasive strategy did not reduce all-cause mortality (RR 1.12, 95% CI 0.97–1.29), cardiac mortality (RR 1.05, 95% CI 0.70–1.58), myocardial infarction (RR 0.90, 95% CI 0.65–1.23), or cardiac-related hospitalization (RR 1.05, 95% CI 0.78–1.40). Conclusions This is the first meta-analysis assessing the effect of a routine invasive strategy in patients with prior CABG who present with NSTE-ACS. The results confirm the under-representation of this patient group in RCTs of invasive management in NSTE-ACS and suggest that there is no benefit to a routine invasive strategy compared to a conservative approach with regard to major adverse cardiac events. These findings should be validated in an adequately powered RCT. [ABSTRACT FROM AUTHOR]

Aims In chronic coronary syndrome (CCS) patients with documented coronary artery disease (CAD), ischaemia detection by myocardial perfusion imaging (MPI) and an invasive approach are viable diagnostic strategies. We compared the diagnostic performance of quantitative flow ratio (QFR) with single-photon emission computed tomography (SPECT), positron emission tomography (PET), and cardiac magnetic resonance imaging (CMR) in patients with prior CAD [previous percutaneous coronary intervention (PCI) and/or myocardial infarction (MI)]. Methods and results This PACIFIC-2 sub-study evaluated 189 CCS patients with prior CAD for inclusion. Patients underwent SPECT, PET, and CMR followed by invasive coronary angiography with fractional flow reserve (FFR) measurements of all major coronary arteries (N = 567), except for vessels with a sub-total or chronic total occlusion. Quantitative flow ratio computation was attempted in 488 (86%) vessels with measured FFR available (FFR ≤0.80 defined haemodynamically significant CAD). Quantitative flow ratio analysis was successful in 334 (68%) vessels among 166 patients and demonstrated a higher accuracy (84%) and sensitivity (72%) compared with SPECT (66%, P < 0.001 and 46%, P = 0.001), PET (65%, P < 0.001 and 58%, P = 0.032), and CMR (72%, P < 0.001 and 33%, P < 0.001). The specificity of QFR (87%) was similar to that of CMR (83%, P = 0.123) but higher than that of SPECT (71%, P < 0.001) and PET (67%, P < 0.001). Lastly, QFR exhibited a higher area under the receiver operating characteristic curve (0.89) than SPECT (0.57, P < 0.001), PET (0.66, P < 0.001), and CMR (0.60, P < 0.001). Conclusion QFR correlated better with FFR in patients with prior CAD than MPI, as reflected in the higher diagnostic performance measures for detecting FFR-defined, vessel-specific, significant CAD. [ABSTRACT FROM AUTHOR]

Aims Coronary flow capacity (CFC) integrates quantitative hyperaemic myocardial blood flow (hMBF) and coronary flow reserve (CFR) to comprehensively assess physiological severity of coronary artery disease (CAD). This study evaluated the effects of revascularization on CFC as assessed by serial [15O]H2O positron emission tomography (PET) perfusion imaging. Methods and results A total of 314 patients with stable CAD underwent [15O]H2O PET imaging at baseline and after myocardial revascularization to assess changes in hMBF, CFR, and CFC in 415 revascularized vessels. Using thresholds for ischaemia and normal perfusion, vessels were stratified in five CFC categories: myocardial steal, severely reduced CFC, moderately reduced CFC, minimally reduced CFC, and normal flow. Additionally, the association between CFC increase and the composite endpoint of death and non-fatal myocardial infarction (MI) was studied. Vessel-specific CFC improved after revascularization (P < 0.01). Furthermore, baseline CFC was an independent predictor of CFC increase (P < 0.01). The largest changes in ΔhMBF (0.90 ± 0.74, 0.93 ± 0.65, 0.79 ± 0.74, 0.48 ± 0.61, and 0.29 ± 0.66 mL/min/g) and ΔCFR (1.01 ± 0.88, 0.99 ± 0.69, 0.87 ± 0.88, 0.66 ± 0.91, and −0.01 ± 1.06) were observed in vessels with lower baseline CFC (P < 0.01 for both). During a median follow-up of 3.5 (95% CI 3.1–3.9) years, an increase in CFC was independently associated with lower rates of death and non-fatal MI (HR 0.43, 95% CI 0.19–0.98, P = 0.04). Conclusion Successful revascularization results in an increase in CFC. Furthermore, baseline CFC was an independent predictor of change in hMBF, CFR, and subsequently CFC. In addition, an increase in CFC was associated with a favourable outcome in terms of death and non-fatal MI. [ABSTRACT FROM AUTHOR]

Aims To compare cardiac magnetic resonance (CMR) measurement of T1 reactivity (ΔT1) with [15O]H2O positron emission tomography (PET) measurements of quantitative myocardial perfusion. Methods and results Forty-three patients with suspected obstructed coronary artery disease underwent [15O]H2O PET and CMR at 1.5-T, including rest and adenosine stress T1 mapping (ShMOLLI) and late gadolinium enhancement to rule out presence of scar tissue. ΔT1 was determined for the three main vascular territories and compared with [15O]H2O PET-derived regional stress myocardial blood flow (MBF) and myocardial flow reserve (MFR). ΔT1 showed a significant but poor correlation with stress MBF (R 2 = 0.04, P  =   0.03) and MFR (R 2 = 0.07, P  =   0.004). Vascular territories with impaired stress MBF (i.e. ≤2.30 mL/min/g) demonstrated attenuated ΔT1 compared with vascular territories with preserved stress MBF (2.9 ± 2.2% vs. 4.1 ± 2.2%, P  =   0.008). In contrast, ΔT1 did not differ between vascular territories with impaired (i.e. <2.50) and preserved MFR (3.2 ± 2.6% vs. 4.0 ± 2.1%, P  =   0.25). Receiver operating curve analysis of ΔT1 resulted in an area under the curve of 0.66 [95% confidence interval (CI): 0.57–0.75, P  =   0.009] for diagnosing impaired stress MBF and 0.62 (95% CI: 0.53–0.71, P  =   0.07) for diagnosing impaired MFR. Conclusions CMR stress T1 mapping has poor agreement with [15O]H2O PET measurements of absolute myocardial perfusion. Stress T1 and ΔT1 are lower in vascular territories with reduced stress MBF but have poor accuracy for detecting impaired myocardial perfusion. [ABSTRACT FROM AUTHOR]

Aims  Myocardial ischaemic burden (IB) is used for the risk stratification of patients with coronary artery disease (CAD). This study sought to define a prognostic threshold for quantitative [15O]H2O positron emission tomography (PET)-derived IB. Methods and results  A total of 623 patients with suspected or known CAD who underwent [15O]H2O PET perfusion imaging were included. The endpoint was a composite of death and non-fatal myocardial infarction (MI). A hyperaemic myocardial blood flow (hMBF) and myocardial flow reserve (MFR)-derived IB were determined. During a median follow-up time of 6.7 years, 62 patients experienced an endpoint. A hMBF IB of 24% and MFR IB of 28% were identified as prognostic thresholds. Patients with a high hMBF or MFR IB (above threshold) had worse outcome compared to patients with a low hMBF IB [annualized event rates (AER): 2.8% vs. 0.6%, P  < 0.001] or low MFR IB [AER: 2.4% vs. 0.6%, P  < 0.001]. Patients with a concordant high IB had the worst outcome (AER: 3.1%), whereas patients with a concordant low or discordant IB result had similar and low AERs of 0.5% and 0.9% (P  = 0.953), respectively. Both thresholds were of prognostic value beyond clinical characteristics, however, only the hMBF IB threshold remained predictive when adjusted for clinical characteristics and combined use of the hMBF and MFR thresholds. Conclusion  A hMBF IB ≥24% was a stronger predictor of adverse outcome than an MFR IB ≥28%. Nevertheless, classifying patients according to concordance of IB result allowed for the identification of low- and high-risk patients. [ABSTRACT FROM AUTHOR]