Key result
Drug-induced LQTS linked to ~4.5 ms higher baseline short-term QT variability versus controls.
Why the study?
Animal models of drug-induced long-QT syndrome showed beat-to-beat variability of repolarization duration had higher proarrhythmia predictive value than QT intervals, prompting evaluation in patients.
Does short-term variability of QT intervals (STV(QT)) identify patients at risk for drug-induced Torsades de pointes better than QTc prolongation?
Population
20 patients with documented TdP under QT-prolonging drugs without major LQTS mutations and 20 matched controls
Comparison
Patients with drug-induced LQTS and TdP vs matched controls
Design
Observer-blinded case-control pilot study
Authors
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Hypothesis-generating for QT variability as TdP risk marker in dLQTS; prospective validation required before clinical adoption.
Case-Control (n=40)
Single-blind
Does short-term variability of QT intervals (STV(QT)) identify patients at risk for drug-induced Torsades de pointes better than QTc prolongation?
Absolute Event Rate: 8.1% vs 3.6%
p-value: p=0.001
Short-term variability of QT intervals (STV(QT)) is a superior non-invasive parameter compared to QTc for identifying patients at risk of drug-induced Torsades de pointes.
Hinterseer et al. (2007) conducted a case-control in Drug-induced long-QT syndrome (dLQTS) and Torsades de pointes (TdP) (n=40). Short-term variability of QT intervals (STV(QT)) vs. Matched control individuals was evaluated on Short-term variability of QT intervals (STV(QT)) (p=0.001). Baseline short-term variability of QT intervals was significantly higher in patients with drug-induced long-QT syndrome compared to controls (8.1 vs 3.6 ms, P=0.001).
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