Abstract 12927: Risk Stratification For Sudden Cardiac Death and Serious Arrhythmic Events Using Heart Rate Turbulence and Nonsustained Ventricular Tachycardia Drom 24-Hour Holter Electrocardiogram in Patients With Impaired Left Ventricular Function
Background: Previous studies have described the clinical usefulness of heart rate turbulence (HRT), an autonomic predictor of mortality, and the presence of nonsustained ventricular tachycardia (NSVT) in stratifying patients with structural heart disease at risk. Although numerous noninvasive risk-stratifiers have been shown to be useful, the predictive values of them alone in predicting serious cardiac events have low positive predictive value. We prospectively assessed whether HRT can facilitate the predictive accuracy of the documentation of NSVT for identifying patients at risk of sudden cardiac death (SCD) and serious ventricular tachyarrhythmias (VTs) in patients with left ventricular dysfunction (LVD) or not.
Methods: We enrolled 299 consecutive patients with LVD (LV ejection fraction <40%) including ischemic (n=184) and nonischemic causes (n=115). HRT was measured using an algorithm based on routine 24-hour Holter electrocardiograms (ECGs), assessing two parameters: turbulence onset (TO) and turbulence slope (TS). HRT was considered positive when both TO was > 0% and TS was < 2.5 msec/R-R interval. NSVT was simultaneously documented from Holter ECGs. The endpoint was defined as SCD and sustained VTs.
Results: Of patients enrolled, 17 patients (5.6%) were not utilized for HRT assessment because of atrial fibrillations and other reasons. Sixty-eight of 282 patients (24.1%) were HRT-positive. During follow-up of 960 ± 444 days, 14 patients (5.0%) reached the endpoint. The Hazard Ratio (HR) of patients with a HRT-positive outcome, the presence of NSVT and the combination were 4.3 (P = 0.0079), 4.1 (P = 0.0065), and 7.6 (P < 0.0001) for the endpoint. On multivariate analysis, the combination was the strongest predictor for the endpoint, with a HR of 6.0 (95%CI, 2.1-16.7; P = 0.0006). Predictive accuracy of NSVT, HRT and the combination were 69%, 77% and 88%, respectively. Although the negative predictive value remained same when they were combined, the predictive accuracy of combined assessment was significantly higher than it of NSVT or HRT alone (P = 0.0004, P <0.0001, respectively).
Conclusions: HRT can facilitate the predictive accuracy of NSVT for identifying patients at risk of SCD and fatal VTs in patients with reduced LV function.
- Heart rate/Heart rate variability
- Autonomic nervous system
- Ventricular arrhythmia
- Sudden cardiac death
- Myocardial infarction
- © 2011 by American Heart Association, Inc.