Myocardial perfusion predicts adverse outcomes in patients with prior CABG

Global stress myocardial blood flow (MBF) and perfusion reserve (MPR) derived from perfusion mapping cardiac magnetic resonance (CMR) are independently predictive of adverse outcomes in patients with prior coronary artery bypass graft (CABG), reports a study.

“This effect is independent from the presence of regional ischemia on visual assessment and the extent of previous infarction,” the authors said.

This retrospective analysis of consecutive patients with previous CABG referred for adenosine stress perfusion CMR determined whether global stress MBF and MPR independently predicted adverse outcome in this population. The authors carried out perfusion mapping in line with automated quantification of MBF.

A composite of all-cause mortality and major adverse cardiovascular events, defined as nonfatal myocardial infarction and unplanned revascularization, was the primary outcome. The authors assessed associations using Cox proportional hazards models, adjusted for comorbidities and CMR parameters.

Overall, 341 patients (median age 67 years, 86 percent male) were included in the analysis, of whom 81 (24 percent) reached the primary outcome over a median follow-up of 638 days (interquartile range 367‒976 days).

After adjusting for known prognostic factors (ie, regional ischaemia and infarction), stress BMF and MPR independently predicted the outcomes. The adjusted hazard ratios were 2.56 (95 percent confidence interval [CI], 1.45‒4.35) for 1 mL/g/min of decrease in stress MBF and 1.61 (95 percent CI, 1.08‒2.38) for 1 unit of decrease in MPR.

“Patients with previous CABG surgery typically have complex coronary disease and remain at high risk of adverse events,” the authors said. “Quantitative myocardial perfusion indices predict outcomes in native vessel disease.”