Abstract 12969: Rapid Nonsustained Ventricular Tachycardia Detected by Continuous Device Monitoring for Risk Stratification in Hypertrophic Cardiomyopathy: Redefining a Traditional Risk Marker
Introduction: Nonsustained VT (NSVT) detected by Holter (Holter +NSVT) is a major risk factor (RF) for sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM). We hypothesized that using a higher heart rate cut-off and prolonged monitoring for detecting NSVT would improve its accuracy in predicting sustained ventricular arrhythmias (VA).
Methods: We prospectively enrolled 56 patients (mean 44±14 yrs) with HCM, who had a preexisting prophylactic ICD. We assessed the prevalence of rapid NSVT (+RNSVT, ≥4 beats at 167-200 bpm) detected by their ICD within the first 12 months of implant. The primary outcome was appropriate ICD therapy after implant.
Results: The prevalence of RF at ICD implant was 50% for syncope, 57% for Holter +NSVT, 45% for +family history SCD, and 25% for septum ≥ 30mm. The prevalence of 0, 1, 2 and ≥3 RF was 2, 32, 54 and 13%, respectively. +RNSVT occurred in 19 patients (34%) of whom 4 were Holter -NSVT. When compared to -RNSVT, those with +RNSVT had less syncope (21 vs 65%, p=0.004) but more Holter +NSVT (79 vs 46%, p=0.02).
Over a median follow-up of 59 (25, 123) months after ICD implant, 8 patients had ≥1 appropriate ICD therapy from VA. According to the number of RF, the proportion of patients with VA was 0=0%, 1=6%, 2=13%, ≥3=43% (p=0.11). +RNSVT was associated with higher VA compared to Holter +NSVT (Figure 1A). +RNSVT predicted VA by Cox regression analysis, both univariate [odds ratio 10, 95% CI 1-84, p=0.03] and adjusted for differences in RF [adjusted odds ratio 11, 95% CI 1-114, p=0.046]. ROC analysis for +RNSVT (area under curve 0.78, p=0.02) showed the optimal cut-point to be RNSVT ≥2 episodes (Figure 1B) for discriminating patients with and without VA (Sensitivity 71%, Specificity 83%, PPV 38%, NPV 95%).
Conclusions: RNSVT detected from continuous device monitoring is an independent predictor of VA in HCM patients and a better risk stratifier than Holter +NSVT. The role of implantable loop monitoring to detect RNSVT and evaluate VA risk in HCM warrants study
Author Disclosures: K. Viswanathan: None. A.M. Suszko: None. N.M. Jackson: None. D. Cameron: None. D.A. Spears: None. H. Rakowski: None. A. Woo: None. M. Khurana: None. V.S. Chauhan: None.
- © 2014 by American Heart Association, Inc.