Long-term survival benefit of coronary revascularization in patients undergoing stress myocardial perfusion imaging

Background: We assessed during a long-term follow-up the relationship between clinical outcome and coronary revascularization according to stress gated myocardial perfusion single-photon emission computed tomography (MPS) findings in an observational series of patients with suspected or known coronary artery disease (CAD). Methods and Results: The study group comprised 2059 patients. During a median follow-up of 61 months, 184 events occurred (126 cardiac death and 58 nonfatal myocardial infarction). The impact of revascularization during follow-up on event-free survival was evaluated with the extended Cox regression model, adjusting for potential clinical and MPS confounders. Revascularization was treated as a binary non-reversible time-dependent covariate. Predefined interactions tested were: 1) revascularization and summed difference score (SDS); 2) revascularization and post-stress left ventricular (LV) ejection fraction (EF); and 3) SDS and post-stress LVEF. Revascularization had a significant effect on event-free survival (adjusted hazard ratio 0.19; P<0.001). Significant interactions were found between revascularization and SDS (P=0.045) and LVEF and SDS (P=0.015). The protective effect of revascularization augmented as SDS increased. For SDS <6 the reduction in hazard ratio was detectable only for reduced LVEF. Conclusions: Both the degree of stress-induced ischemia and LVEF predict the effect of revascularization on outcome in patients with suspected or known CAD. The protective effect of revascularization seems more evident in patients with severe ischemia and preserved LVEF.