Abstract 12624: Turbulence Induced T-wave Alternans at Elevated Heart Rates Predicts Risk of Arrhythmias in Post Acute Myocardial Infarction Patients
Background: Stratification of patients at risk of sudden cardiac death after acute myocardial infarction (AMI) remains a significant unmet clinical need. We hypothesized that turbulence induced T-wave alternans (TI-TWA) after premature ventricular contractions (PVC) at elevated heart rates is associated with vulnerability to life-threatening arrhythmias in post-AMI patients.
Methods: A total of 5869 consecutive patients were screened in 10 European centers, and 312 patients (age 65 ± 11 years) with a mean LVEF of 31 ± 6% were included in the CARISMA study. A total of 191 patients provided analyzable 24hr holters acquired 5–21 days following the index MI. PVC with compensatory pauses were selected for analysis. TI-TWA was measured on modified V3 lead from the 16 beats following the PVC using the modified moving average method. The associations between TI-TWA at maximum heart rate (maxHR) and the study endpoints were analyzed using Cox and logistic regression methods. The primary endpoint (PE) was ECG-documented ventricular fibrillation or symptomatic sustained ventricular tachycardia (>30 sec) adjudicated as ‘most probably treatable by an ICD’ according to the consensus of the 5-member committee blinded to outcome. Secondary endpoints included all-cause mortality (ACM) and cardiac death (CD).
Results: During a median follow up of 24.2 months and among the 191 patients studied, there were 15 PE, 20 ACM and 14 CD. A median of 12 (inter-quartile range 3–59) PVCs were analyzed per patient. On a continuous analysis, TI-TWA at maxHR (81 ±14 bpm) was associated with the PE (Area under the ROC 0.71 ± 0.06, p = 0.001). After adjusting for covariates (age, prior MI, history of congestive heart failure, and diabetes), dichotomized TI-TWA at maxHR using a cut-point of 95μV was a strong predictor of PE (HR=13.8 [1.8–105.2], p=0.012) but not ACM (HR=1.29 [0.52–3.21], p=0.586) or CD (HR=2.18 [0.68–7.05], p=0.191). Dichotomized TI-TWA at maxHR identified 93% of patients who developed the PE with positive predictive and negative predictive values of 15% and 99% respectively.
Conclusion: TI-TWA at elevated heart rates measured early post-AMI in patients with LVEF≤0.40 is a strong novel risk marker for ventricular tachyarrhythmia and may guide ICD therapy.
- © 2010 by American Heart Association, Inc.