Abstract 10947: Longer and Faster Non-sustained Ventricular Tachycardia in Hypertrophic Cardiomyopathy Patients Predicts for Implantable Cardioverter Defibrillator Shocks and Sudden Cardiac Death

Abstract

Introduction: Non-sustained ventricular tachycardia (NSVT) may be underestimated in patients with hypertrophic cardiomyopathy (HCM). Its impact on the risk of sudden cardiac death (SCD) in HCM is controversial. There is no distinction made in the guidelines as to the length or rate of NSVT as a risk marker for SCD. Hypothesis: NSVT may be nearly universal in HCM patients with high risk of SCD and not found because of the limited time frame of monitoring. NSVT may be associated with appropriate Implantable Cardioverter Defibrillator (ICD) shocks and SCD. Methods: A retrospective study of 181 HCM patients who had an ICD and were followed for at least 6 months from 2000 to 2013 at Tufts Medical Center was performed. The pre-operative evaluations as well as routine ICD follow up notes were reviewed. Results: ICD was implanted in 175 (96.7%) patients as primary prevention and in 6 (3.3%) patients as secondary prevention for SCD. Ninety six (53.0%) patients total had NSVT, including 48 (26.5%) before and 77 (42.5%) after ICD implantation. The agreement for detecting NSVT between Holter monitoring and ICD interrogation was poor (Kappa=0.18, p=0.054). Eighteen (18.75%) patients with NSVT and 6 (7.06%) patients without NSVT had appropriate ICD shocks or SCD (Figure 1). In multivariable analysis, NSVT was independently associated with appropriate ICD shocks and SCD (OR 3.69, 95%CI: 1.31 - 10.43) and remained significant in the 175 patients who had ICD implanted as primary prevention (OR 3.86, 95%CI: 1.13 - 13.18). More rapid NSVT (Cl < 310ms) predicted appropriate ICD shocks and SCD (OR 7.7, 95%CI: 1.6, 36.8), and longer NSVT (> 18beats) also predicted appropriate ICD shocks and SCD (OR=23.7, 95%CI: 2.7, 204.9). Conclusion: The agreement for detecting NSVT between Holter and ICD interrogation is poor. NSVT is significantly associated with appropriate ICD shocks and SCD. Faster and longer NSVT are even more predictive. Extending rhythm monitor time merits consideration in HCM patients.