Prognostic value of global myocardial flow reserve in patients with history of coronary artery bypass grafting
Mahmoud Al Rifai, Ahmed Ibrahim Ahmed, Jean Michel Saad, Fares Alahdab, Faisal Nabi, Mouaz H. Al‐Mallah
Abstract
AIMS: It is not well understood whether positron emission tomography (PET)-derived myocardial flow reserve (MFR) is prognostic among patients with prior coronary artery bypass grafting (CABG). METHODS AND RESULTS: Consecutive patients with a clinical indication for PET were enrolled in the Houston Methodist DeBakey Heart and Vascular Center PET registry and followed prospectively for incident outcomes. The primary outcome was a composite of all-cause death, myocardial infarction (MI)/unplanned revascularization, and heart failure admissions. Cox proportional hazards models were used to study the association between MFR (<2 vs. ≥2) and incident events adjusting for clinical and myocardial perfusion imaging variables. The study population consisted of 836 patients with prior CABG; mean (SD) age 68 (10) years, 53% females, 79% Caucasian, 36% non-Hispanic, and 66% with MFR <2. Over a median (interquartile range [IQR]) follow-up time of 12 (4-24) months, there were 122 incident events (46 HF admissions, 28 all-cause deaths, 23 MI, 22 PCI/3 repeat CABG 90 days after imaging). In adjusted analyses, patients with impaired MFR had a higher risk of the primary outcome [hazard ratio (HR) 2.06; 95% CI 1.23-3.44]. Results were significant for admission for heart failure admissions (HR 2.92; 95% CI 1.11-7.67) but not for all-cause death (HR 2.01, 95% CI 0.85-4.79), or MI/UR (HR 1.93, 95% CI 0.92-4.05). CONCLUSION: Among patients with a history of CABG, PET-derived global MFR <2 may identify those with a high risk of subsequent cardiovascular events, especially heart failure, independent of cardiovascular risk factors and perfusion data.