Key result
Hypertrophic cardiomyopathy was associated with a 41% relative increase in short-term beat-to-beat variability of the QT interval compared to healthy controls.
Why the study?
Are repolarization parameters, specifically beat-to-beat short-term QT interval variability (QT-STV), increased and correlated with left ventricular hypertrophy in patients with hypertrophic cardiomyopathy?
Case-Control (n=74)
No
Are repolarization parameters, specifically beat-to-beat short-term QT interval variability (QT-STV), increased and correlated with left ventricular hypertrophy in patients with hypertrophic cardiomyopathy?
Answers are grounded in this paper and cite their sources.
Beat-to-beat short-term QT interval variability is significantly increased in patients with hypertrophic cardiomyopathy and correlates with left ventricular hypertrophy, suggesting potential utility as a marker for sudden cardiac death risk.
Stratification models for the prediction of sudden cardiac death (SCD) are inappropriate in patients with hypertrophic cardiomyopathy (HCM). We investigated conventional electrocardiogram (ECG) repolarization parameters and the beat-to-beat short-term QT interval variability (QT-STV), a new parameter of proarrhythmic risk, in 37 patients with HCM (21 males, average age 48 ± 15 years). Resting ECGs were recorded for 5 min and the frequency corrected QT interval (QTc), QT dispersion (QTd), beat-to-beat short-term variability of QT interval (QT-STV), and the duration of terminal part of T waves (Tpeak-Tend) were calculated. While all repolarization parameters were significantly increased in patients with HCM compared with the controls (QTc, 488 ± 61 vs. 434 ± 23 ms, p < 0.0001; QT-STV, 4.5 ± 2 vs. 3.2 ± 1 ms, p = 0.0002; Tpeak-Tend duration, 107 ± 27 vs. 91 ± 10 ms, p = 0.0015; QTd, 47 ± 17 vs. 34 ± 9 ms, p = 0.0002), QT-STV had the highest relative increase (+41%). QT-STV also showed the best correlation with indices of left ventricular (LV) hypertrophy, i.e., maximal LV wall thickness normalized for body surface area (BSA; r = 0.461, p = 0.004) or LV mass (determined by cardiac magnetic resonance imaging) normalized for BSA (r = 0.455, p = 0.015). In summary, beat-to-beat QT-STV showed the most marked increase in patients with HCM and may represent a novel marker that merits further testing for increased SCD risk in HCM.
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Orosz et al. (2015) conducted a case-control in Hypertrophic cardiomyopathy (n=74). Hypertrophic cardiomyopathy vs. Healthy volunteers was evaluated on Short-term beat-to-beat variability of the QT interval (QT-STV) (+41% relative increase, p=0.0002). Hypertrophic cardiomyopathy was associated with a 41% relative increase in short-term beat-to-beat variability of the QT interval compared to healthy controls.
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