Prognostic value of "routine" cardiac stress imaging 5 years after percutaneous coronary intervention: the prospective long-term observational BASKET (Basel Stent Kosteneffektivitäts Trial) LATE IMAGING study

Objective: This study sought to evaluate the prognostic value of routine stress myocardial perfusion scintigraphy (MPS) 5 years after percutaneous coronary intervention (PCI).

Background: Current appropriate use criteria define routine cardiac stress imaging <2 years after PCI as inappropriate and >2 years as uncertain in asymptomatic patients.

Methods: All 339 of 683 BASKET (Basel Stent Kosteneffektivitäts Trial) 5-year survivors (55%) consenting to undergo protocol-mandated MPS and subsequent evaluation irrespective of symptoms were followed for major adverse cardiac events (MACE) (cardiac death, myocardial infarction [MI], or revascularization). For MPS, summed perfusion scores were calculated and perfusion defects were related to treated-vessel or remote myocardial areas.

Results: Patients were 72 ± 10 years of age, 18% were female, and 90% were free of angina. MPS findings were abnormal in 205 of 339 patients (60%) with complete follow-up. During 3.7 ± 0.3 years, there were 7 cardiac deaths, 18 MIs, and 47 revascularizations, resulting in a MACE rate of 4.4% and a cardiac mortality rate of 0.6% per year. Patients with abnormal MPS findings had higher hazard ratios (HR) for MACE (HR: 1.95; 95% confidence interval [CI]: 1.06 to 3.59; p = 0.032), and cardiac death/MI (HR: 2.50; 95% CI: 0.93 to 6.69; p = 0.066) than patients with normal MPS finding. MACE rates were similar in patients with symptomatic and silent ischemia (p = 0.61) but higher than in patients with normal MPS findings (p < 0.05 for both comparisons). MACE rates were independently predicted by remote ischemia but not by treated-vessel ischemia or scar.

Conclusions: Abnormal MPS findings 5 years after PCI are frequent irrespective of symptoms. The predictive power of abnormal MPS lies more in the detection of persistent or progressing coronary artery disease in remote vessel areas than in the diagnosis of late intervention-related problems in treated vessels.