Clinical outcomes after chronic total occlusion percutaneous coronary intervention: impact of baseline ischemic burden assessed by SPECT

Background and purpose: Although percutaneous coronary intervention for chronic total occlusion (CTO-PCI) is performed to reduce ischemia and relieve symptoms, its clinical effectiveness varies, and the value of baseline ischemic burden assessed by single-photon emission computed tomography (SPECT) for predicting benefit remains uncertain. This study aimed to evaluate the reduction in ischemic burden after successful CTO-PCI, identify baseline and angiographic factors associated with significant ischemia improvement, and examine whether ischemia reduction was associated with subsequent improvement in angina and health status. Methods: In this retrospective cohort study, patients who underwent successful CTO-PCI received SPECT imaging before and within 3 days after the procedure to quantify myocardial ischemia. Health status was assessed at baseline and 24 months using the Seattle Angina Questionnaire (SAQ). Significant ischemia improvement was defined as an absolute reduction of ≥5% in ischemic myocardium. Results: The study included 74 patients (mean age: 57.2 ± 12.5 years; 89.2% male), of whom 29 (39.2%) achieved significant ischemia improvement. Compared with patients without improvement, those with improvement had a lower prevalence of hypertension (41.4% vs. 75.6%; P = 0.003), greater baseline ischemic myocardium (20.6% ± 12.7% vs. 9.6% ± 6.9%; P < 0.001), and a larger reduction in ischemic myocardium (8.8% ± 3.9% vs. 1.6% ± 2.5%; P < 0.001). In multivariable logistic regression, sex (male vs. female: odds ratio [OR]: 0.093, 95% confidence interval [95% CI]: 0.011–0.819; P = 0.032), baseline ischemic myocardium (OR: 1.156, 95% CI: 1.052–1.269; P = 0.003), and left anterior descending artery CTO (LAD-CTO; OR: 5.132, 95% CI: 1.122–23.478; P = 0.035) were independently associated with ischemia improvement. Baseline ischemic burden predicted a ≥5% reduction in ischemia with an area under the receiver operating characteristic curve of 0.800 and an optimal cutoff of 13.0%. Discrimination was particularly high in patients with LAD-CTO. At 24 months, improvements in all SAQ domains were greater among patients with ischemia improvement than among those without improvement. Conclusions: Successful CTO-PCI was associated with greater reductions in ischemia and greater symptomatic improvement among patients with a higher baseline SPECT-derived ischemic burden, particularly those with LAD-CTO. Baseline ischemic burden may help identify patients most likely to benefit from CTO-PCI.