Background: Implantable cardioverter defibrillator (ICD) implantation for secondary prevention is recommended in patients with sustained ventricular arrhythmias (VA) in absence of reversible causes. Residual myocardial ischemia might be a trigger for VA. Hence, complete coronary revascularization may be an important factor to reduce the burden of recurrent ventricular arrhythmic events.
Purpose: Aim of this study was to assess whether incomplete coronary revascularization is associated with an increase of appropriate device therapy (ADT) in secondary prevention ICD patients with coronary artery disease (CAD).
Methods: 135 consecutive patients with ischemic heart disease (89% men, age 65 ± 10 years, LVEF 38 ± 11%) who received an ICD for secondary prevention between January 2011 and June 2017 were retrospectively included. All patients experienced ventricular fibrillation (VF) or sustained ventricular tachycardia (VT) and underwent a coronary angiogram (CAG) prior ICD implantation. CAGs were reviewed to determine if obstructive CAD was present. Incomplete revascularization was defined as =1 remaining coronary stenoses >70% in the main coronary vessels or large side-branches after ICD implantation. Coronary chronic total occlusions (CTO) who were treated conservatively were included in the incomplete revascularization group. Patients without obstructive CAD were known with a coronary stenosis <70% or received successful percutaneous coronary intervention or coronary artery bypass surgery. Clinical and laboratory variables and data about cardiac function assessed by cardiac magnetic resonance were entered in a multivariate cox regression model. ADT was defined as anti-tachycardia pacing (ATP) or shock for VT or VF.
Results: During a mean follow-up of 3.5±1.9 years, 52 (39%) patients received ADT and 17 (13%) died. Median time between CAG and ICD implantation was 15 days (IQR 0-30 days). Incomplete revascularization was found in 56 (42%) patients. Patients with incomplete revascularization received ADT more frequently compared to patients without obstructive CAD (52% vs. 29%, respectively; HR 2.05, 95% CI 1.18-3.53, p=0.01). The cumulative number of ATP or shock in patients with ADT was higher in patients with incomplete revascularization (mean number of ADT 3.8±4.0 vs. 2.1±1.2, p=0.045). A subanalysis with CTO patients (n=80) showed a trend towards more ADT in patients who were treated conservatively (HR 2.06; 95% CI 0.94–4.52; p=0.07). A multivariate analysis showed that incomplete revascularization (HR 2.2, 95% CI 1.13-3.97, p=0.02) and increased end diastolic volume (HR 1.13, 95% CI 1.01-1.26, p=0.04) were both independent predictors of ADT.
Conclusion: Secondary prevention ICD patients with CAD and incomplete revascularization are at higher risk for ADT and recurrent ventricular arrhythmic events. This study suggests that it is important to strive for complete revascularization prior to ICD implantation in patients with ischemic heart disease.