Low heart rate variability was specifically associated with susceptibility to ventricular fibrillation (p<0.001), whereas increased QTc dispersion was associated with vulnerability to both VF and VT.
Case-Control (n=165)
Are QT dispersion and heart rate variability associated with specific vulnerability to ventricular tachycardia versus ventricular fibrillation after a previous myocardial infarction?
Low heart rate variability specifically identifies susceptibility to ventricular fibrillation, while increased QT dispersion is a general marker for vulnerability to both ventricular tachycardia and fibrillation after myocardial infarction.
valor p: p=<0.001
OBJECTIVES: This study was designed to compare QT dispersion measured from the standard 12-lead electrocardiogram and 24-h heart rate variability in patients with vulnerability to either ventricular tachycardia or ventricular fibrillation after a previous myocardial infarction. BACKGROUND: Increased QT interval dispersion and reduced heart rate variability have been shown to be associated with vulnerability to ventricular tachyarrhythmias, but the data have mainly been pooled from patients with presentation of stable ventricular tachycardia and ventricular fibrillation. METHODS: QT dispersion and time domain and two-dimensional vector analysis of heart rate variability were studied in 30 survivors of ventricular fibrillation with a previous myocardial infarction and with inducible unstable ventricular tachyarrhythmia by programmed electrical stimulation and in 30 postinfarction patients with clinical and inducible stable monomorphic sustained ventricular tachycardia. Both of these patient groups were matched, with respect to age, gender and left ventricular ejection fraction, with an equal number of postinfarction control patients without a history of arrhythmic events or inducible ventricular tachyarrhythmia and arrhythmia-free survival during a follow-up period of 2 years. Forty-five age-matched healthy subjects served as normal control subjects. RESULTS: Standard deviation of all sinus intervals and long-term continuous RR interval variability analyzed from Poincaré plots were reduced in patients with vulnerability to ventricular fibrillation (p < 0.001 for both), but not in patients with ventricular tachycardia (p = NS for both), compared with postinfarction control subjects. Corrected QT (QTc) dispersion was significantly broader both in patients with ventricular fibrillation (p < 0.001) and in those with ventricular tachycardia (p < 0.05) than in matched postinfarction control subjects. Heart rate variability performed better than QTc dispersion in predicting vulnerability to ventricular fibrillation. CONCLUSIONS: Increased QT dispersion is associated with vulnerability to both ventricular tachycardia and ventricular fibrillation. Low heart rate variability is specifically related to susceptibility to ventricular fibrillation but not to stable monomorphic ventricular tachycardia, suggesting that the autonomic nervous system modifies the presentation of life-threatening ventricular arrhythmias.
Perkiömäki et al. (Sat,) conducted a case-control in Vulnerability to ventricular tachycardia and ventricular fibrillation after previous myocardial infarction (n=165). QT dispersion and heart rate variability measurement vs. Postinfarction control patients and healthy subjects was evaluated on Standard deviation of all sinus intervals, long-term continuous RR interval variability, and Corrected QT (QTc) dispersion (p=<0.001). Low heart rate variability was specifically associated with susceptibility to ventricular fibrillation (p<0.001), whereas increased QTc dispersion was associated with vulnerability to both VF and VT.
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