Long-Term Changes in Depolarization and Repolarization after Kawasaki Disease

Abstract

To assess myocardial electric potentials late after coronary involvement secondary to Kawasaki disease (KD) we measured signal-averaged electrocardiography (SAECG) and QT dispersion parameters. Study population included 13 patients (group I) with persistent coronary aneurysm (AN), 12 patients (group II) with AN resolution beyond 3 months of the acute illness (9.2±9 months), and 13 patients (group III) with AN resolution within 3 months of the acute illness (1.3±0.9 months). Measurements were obtained 7.9±3.9, 6.7±3.9, and 7.2±3.6 years after the initial diagnosis of KD in group I, II, and III respectively (p=NS). In group I, myocardial infarction occurred in one patient, and coronary thrombosis in another during the acute illness. All except two patients had giant AN (n=8) and / or coronary artery stenosis (n=7). No short or long-term compications were observed in groups II or III. Depolarization was evaluated by SAECG, and repolarization was evaluated by QT dispersion measurements. At 40Hz high-pass filter SAECG, noise level was 0.39±0.07μV in group I, 0.46±0.14μV in group II, and 0.43±0.14μV in group III (p=NS). Terminal 40-msec root mean square amplitude (RMS40) was significantly lower in group I in comparison to groups II and III (64.1±40.8μV, 79.9±47.2μV, and 115±65.4μV respectively; p<0.05), and low-amplitude signal (<40μV) duration (LASd) showed no significant difference (19.7±7msec, 20.9±8.5msec, and 18.6±7.4msec respectively) (p=NS). Twelve-lead QT dispersion was significantly greater in group I (52±11msec) compared to group III (37±11msec) (p<0.05), but not in comparison to group II (45±13msec). The trend was present for rate-corrected QT dispersion, without reaching statistical significance (84±34, 71±31, and 61±23 respectively; p=0.18). In conclusion, both depolarization and repolarization parameters are altered in patients with persistent coronary AN long-term after KD. These findings may represent risk factors for developing ventricular arrhythmia in a growing population of KD patients. In this perspective, long-term follow-up studies are needed for this population.