Impact of myocardial perfusion abnormalities on clinical outcomes in patients treated with percutaneous coronary intervention for chronic total occlusions.

Introduction: Myocardial perfusion imaging (MPI) is used to evaluate ischaemia in patients with chronic total occlusion (CTO), but its prognostic implications following percutaneous coronary intervention (PCI) of CTO remain uncertain. Purpose: To evaluate outcomes in patients treated with CTO-PCI stratified by moderate-severe ischaemia on MPI prior to intervention. Methods and results: Patients from the Western Danish Heart Registry assessed by nuclear MPI and subsequently treated with CTO-PCI ≤ 6 months were included. Moderate-severe ischaemia was defined as ≥10% left ventricle involvement. Primary endpoints were all-cause mortality and a composite of major adverse cardio- and cerebrovascular events [MACCE; cardiovascular death, myocardial infarction (MI), stroke, and hospitalization for heart failure (HF) or angina pectoris]. Secondary endpoints included the individual MACCE components. Outcomes were compared between patients with and without moderate-severe ischaemia using multivariable Cox regression and competing risk regression at 90-day and 5-year follow-ups. Among 319 patients, 208 (65.2%) had moderate-severe ischaemia. All-cause mortality was similar between patients with and without moderate-severe ischaemia [adjusted hazard ratio (aHR) 1.12, 95% confidence interval (CI): 0.52-2.43], P = 0.77). The estimated risk of MACCE was comparable between groups at 90 days [aHR 0.76 (0.38-1.55), P = 0.46] and 5 years [aHR 0.74 (0.45-1.20), P = 0.22]. No difference was found in MI [5 years: aHR 0.76 (0.26-2.22), P = 0.61] or hospitalization for HF [90 days: aHR 0.44 (0.16-1.21), P = 0.11]; 5 years: aHR 0.62 (0.30-1.30), P = 0.21]. Hospitalization for angina was similar at 90 days [aHR 0.75 (0.26-2.16), P = 0.60], but a decreased 5-year risk was observed in patients with moderate-severe ischaemia [aHR 0.46 (0.23-0.91), P = 0.026]. Conclusion: Moderate-severe ischaemia on nuclear MPI was not associated with differences in mortality or MACCE after CTO-PCI but was associated with a lower long-term risk of angina hospitalization.