Meta-analysis results indicated that left ventricular ejection fraction (LVEF) level, diabetes, smoking, hypertension, coronary artery bypass grafting, angiotensin converting enzyme inhibitor (ACEI)/angiotensin receptor blocker (ARB), β-blockers, age, and renal insufficiency were the factors affecting outcomes after PCI for CTOs [risk ratio and 95% confidence interval were: 0.88 (0.86, 0.90), 0.96 (0.95, 0.96), 0.76 (0.59, 0.98), 1.39 (0.89, 2.16), 0.73 (0.38, 1.40), 0.24 (0.02, 3.9), 0.78 (0.77, 0.79), 0.81 (0.80, 0.82), and 1.50 (0.47, 4.79)]. The gene discussed is ACE; the disease is hypertensive disorder.