Abstract 2895: Steep Activation-Recovery Interval Restitution Predicts the Vulnerability of Ventricular Arrhythmia in Patients with Structural Heart Disease
Electrophysiological abnormalities play a role in occurrence of life-threatening ventricular arrhythmia in patients with structural heart disease. However, risk stratification of patients with implantable cardioverter-defibrillator (ICD) remains to be determined. We hypothesized that the steeply sloped activation-recovery interval (ARI) restitution could predict future ICD-shocks in patients with structural heart diseases. We performed electrophysiological study before ICD implantation and evaluated ARI restitution properties in 20 patients (male 8, female 12, age 63.1±2.7), including patients with ischemic cardiomyopathy (n=7), dilated cardiomyopathy (n=7), hypertrophic cardiomyopathy (n=1), cardiac sarcoidosis (n=2), arrhythmogenic right ventricular cardiomyopathy (n=2), and others (n=1). We observed ICD-shocks in 8 patients during follow-up periods (mean 675 days). Left ventricular (LV) ejection fraction, LV end-diastolic diameter and NYHA class did not differ between ICD-shock and no-shock groups. Although right ventricular effective refractory period and ARI dispersion did not differ between both groups, slope of ARI restitution curve was significantly steeper in ICD-shock group than no-shock group (1.42±0.25 vs. 0.64±0.05 ; P<0.05). The steeply sloped ARI restitution was significantly associated with ICD-shock by univariate Cox hazard analysis. Furthermore, Kaplan-Meier analysis demonstrated that steep ARI restitution (slope>1) could predict subsequent ICD-shock. In conclusion, steep ARI restitution reveals vulnerability of ventricular arrhythmia in patients with structural heart diseases.