PO-05-079 SMOKING AND THE RISK OF VENTRICULAR TACHYARRHYTHMIAS AMONG IMPLANTABLE CARDIOVERTER DEFIBRILLATOR RECIPIENTS FOR PRIMARY PREVENTION OF SUDDEN CARDIAC DEATH

Abstract

Smoking has been linked to increased morbidity and mortality in patients with cardiovascular disease. However, limited data exist regarding the arrhythmic effects of smoking in patients at risk for sudden cardiac death (SCD). We aimed to evaluate the relationship between smoking and the risk of ventricular tachyarrhythmias and SCD. The study population comprised 5,015 patients implanted with an implantable cardioverter defibrillator (ICD) from five landmark randomized ICD trials (MADIT-II, MADIT-CRT, MADIT-RIT, MADIT-RISK, and RAID trials). Patients were categorized into three groups based on smoking status at the time of ICD implantation: non-smokers, past smokers, and current smokers. The primary endpoint was the first occurrence of ventricular tachycardia ≥170 bpm or fibrillation (VT/VF). Secondary endpoints included the composite endpoint of VT/VF or SCD and inappropriate ICD shocks. A competing risk analysis was carried out using the Fine and Gray method to generate cumulative incidence function (CIF) curves and regression models for the defined endpoints. The 5-year cumulative incidence of a first episode of VT/VF was higher in current smokers (32%) than in past- (29%) and non-smokers (25%) (p=0.009, [Figure, left panel]). Consistent results were obtained for the endpoint of inappropriate ICD shocks (10%, 9%, 6%%, respectively; p=0.007, [Figure, right panel]). Multivariate current smoking vs. non-smoking was associated with a significant 25% increased risk of VT/VF (HR=1.25, p=0.034); with a corresponding 28% increased risk of the composite endpoint of VT/VF or SCD (HR=1.28, p=0.014); and with a 49% increased risk of inappropriate ICD shocks (HR=1.49, p=0.03). Conversely, the risk of the aforementioned endpoints was not significantly difference between past-smokers and never-smokers. Patients who smoke at the time of ICD implantation experience a significantly increased risk of VT/VF and inappropriate ICD shocks.