Abstract
BackgroundWe investigated whether multichannel ECG-recordings are useful to risk-stratify patients with congenital long-QT syndrome (LQTS) for risk of sudden cardiac death under optimized medical treatment.MethodsIn 34 LQTS-patients (11 male; age 31±13 years, QTc 478±51ms; LQT1 n = 8, LQT2 n = 15) we performed a standard 12-channel ECG and a 120-channel body surface potential mapping. The occurrence of clinical events (CE; syncope, torsade de pointes (TdP), sudden cardiac arrest (SCA)) was documented and correlated with different ECG-parameters in all lead positions.ResultsSeven patients developed TdP, four survived SCA and 12 experienced syncope. 12/34 had at least one CE. CE was associated with a longer QTc-interval (519±43ms vs. 458±42ms; p = 0.001), a lower T-wave integral (TWI) on the left upper chest (-1.2±74.4mV*ms vs. 63.0±29.7mV*ms; p = 0.001), a lower range of T-wave amplitude (TWA) in the region of chest lead V8 (0.10±0.08mV vs. 0.18±0.07mV; p = 0.008) and a longer T-peak-T-end time (TpTe) in lead V1 (98±23ms vs. 78±26ms; p = 0.04). Receiver-operating-characteristic (ROC) analyses revealed a sensitivity of 96% and a specificity of 75% (area under curve (AUC) 0.89±0.06, p = 0.001) at a cut-off value of 26.8mV*ms for prediction of CE by TWI, a sensitivity of 86% and a specificity of 83% at a cut-off value of 0.11mV (AUC 0.83±0.09, p = 0.002) for prediction of CE by TWA and a sensitivity of 83% and a specificity of 73% at a cut-off value of 87ms (AUC 0.80±0.07, p = 0.005) for prediction of CE by TpTe.ConclusionsOccurrence of CE in LQTS-patients seems to be associated with a prolonged, low-amplitude T-wave.
Highlights
The congenital long QT syndrome (LQTS) is a channelopathy with 13 known different genotypes and more than 500 identified mutations affecting ventricular repolarization
Its penetrance is variable and clinical symptoms range from asymptomatic patients to significant cardiac events such as syncope, torsade de pointes (TdP) tachycardia, sudden cardiac arrest (SCA) or sudden cardiac death (SCD) [1]
I. e. avoidance of QT prolonging drugs, potassium or magnesium deficiency, and trigger situations [5, 6] beta-blocker therapy was found to reduce occurrence of SCA/SCD in patients with long-QT syndrome (LQTS) significantly [7]
Summary
The congenital long QT syndrome (LQTS) is a channelopathy with 13 known different genotypes and more than 500 identified mutations affecting ventricular repolarization. Diagnostic criteria were developed including electrocardiographic parameters like a heart rate corrected QT prolongation above 450ms in male patients and 460ms in female patients, occurrence of TdP, detection of T-wave alternans, clinical features like syncope, congenital deafness and a positive family history [2, 3]. Several other risk factors in patients with LQTS for the occurrence of life-threatening events have been identified: The risk for developing cardiac events is greater in patients with QTc interval > 500ms [5]. Other risk factors for cardiac events are gender and age [7], occurrence of previous symptoms [8, 9] and a family history of SCD [10]. We investigated whether multichannel ECG-recordings are useful to risk-stratify patients with congenital long-QT syndrome (LQTS) for risk of sudden cardiac death under optimized medical treatment
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