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Chronic Total Occlusion and Arrhythmic Outcomes
Study Questions:
What is the relationship between chronic coronary artery total occlusion (CTO) status and the occurrence of ventricular tachycardia/fibrillation (VT/VF) or appropriate implantable cardioverter-defibrillator (ICD) therapy?
Methods:
The investigators searched PubMed and Embase databases identifying 137 studies that investigated the association between CTO status and arrhythmic or mortality endpoints in patients with ischemic heart disease. The predefined endpoints were: appropriate therapy, VT/VF, or sudden cardiac death (SCD). Multivariate hazard ratios (HRs) comparing adverse event rates between the CTO and non-CTO groups based on CTO status were extracted. Heterogeneity between studies was quantified using the I2 statistic from the standard chi-square test, which describes the percentage of the variability in effect estimates resulting from heterogeneity. I2 >50% was considered to reflect significant statistical heterogeneity.
Results:
Seventeen studies involving 54,594 subjects (mean age 61 ± 21 years, 81% male) with a mean follow-up of 43 ± 31 months were included. The presence of CTO was associated with higher risk of VT/VF or appropriate ICD therapy (adjusted HR [aHR], 1.99; 95% confidence interval, 1.53-2.59; p < 0.0001; I2 = 3%), but not in cardiac mortality (aHR, 2.59 [0.64-10.59]; p = 0.18; I2 = 86%) or in all-cause mortality (aHR, 1.70 [0.84-3.46]; p = 0.14; I2 = 64%). Compared to patients with noninfarct-related CTOs, those with infarct-related CTOs have a higher risk of VT/VF or appropriate ICD therapy (aHR, 2.47 [1.76-3.46]; p < 0.0001; I2 = 14%), cardiac mortality (aHR, 2.73; [1.02-7.30]; p < 0.05; I2 = 79%), and higher all-cause mortality (aHR, 1.69 [1.19-2.40]; p < 0.01; I2 = 40%). Non-revascularization of CTOs tended to be associated with an increased risk of all-cause mortality compared to successful revascularization (unadjusted HR, 1.52 [0.96-2.43]; I2 = 76; p = 0.08).
Conclusions:
CTOs, especially infarct-related, are associated with a high risk of VT/VF or appropriate ICD therapy and mortality.
Perspective:
This study reports that the presence of a CTO was associated with a significant increase in the risk of VT/VF or appropriate ICD therapy, but not with cardiac mortality or all-cause mortality. Furthermore, patients with CTOs in an infarct-related coronary artery had a higher risk of VT/VF or appropriate therapy and all-cause mortality, but not in cardiac mortality, than those with noninfarct-related CTOs. Non-revascularization of CTOs was associated with a 1.5-fold increase in the risk of all-cause mortality compared to successful revascularization, although this was not statistically significant. ICD implantation for primary or secondary prevention seems reasonable in patients who have infarct-related CTOs and meet current guideline criteria for ICDs. Given the limitations of the current analysis, additional studies are indicated to identify those who would benefit from revascularization procedures.
Keywords: Arrhythmias, Cardiac, Coronary Artery Disease, Coronary Occlusion, Death, Sudden, Cardiac, Defibrillators, Implantable, Myocardial Ischemia, Myocardial Revascularization, Primary Prevention, Secondary Prevention, Tachycardia, Ventricular, Ventricular Fibrillation
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