[Predictive value of QT interval dynamicity for sudden death in patients with idiopathic dilated cardiomyopathy].

OBJECTIVE: To explore the predictive value of QT interval dynamicity for sudden death in patients with idiopathic dilated cardiomyopathy (DCM).

METHODS: Fifty-five patients with DCM (DCM group) and 27 healthy subjects (Control group, Con) were enrolled. Investigations included history collection, clinical examination, echocardiography, electrocardiogram and 24 h ambulatory electrocardiogram. Following indexes were determined: left ventricle end diastolic dimension (LVEDD), left ventricle ejection fraction (LVEF), QT dispersion (QTd), SDNN, the slope of QT/RR plots of the linear regression, ventricular premature beats (VPB) and non-sustained ventricular tachycardia (NSVT). Primary end point for patients with DCM was all cause death.

RESULTS: LVEDD, QTd, VPB/24 h, NSVT/24 h, QTe/RR slope and QTp/RR slope were significantly higher while LVEF and SDNN were significantly lower in DCM group than in Con group (all P < 0.05). LVEDD, LVEF, QTd, SDNN, QTe/RR slope and QTp/RR slope were significantly different among DCM sudden death group, DCM non sudden death group and Con group (P < 0.05). LVEF, SDNN, QTe/RR slope and QTp/RR slope were significantly different between DCM sudden death and non sudden death group (P < 0.05). LVEF, QTd, VPB/24 h, QTe/RR slope and QTp/RR slope were significantly different between DCM with NSVT and DCM without NSVT group (P < 0.05). The sudden death rate of DCM patients with QTe/RR slope ≥ 0.210 was significantly higher than DCM patients with QTe/RR slope < 0.210 (54.5% vs. 21.1%, P < 0.05). Sudden death rate of QTp/RR slope ≥ 0.190 was also higher than those < 0.190 (52.2% vs. 21.9%, P < 0.05). The sudden death rate of DCM patients with both LVEF ≤ 35% and NSVT+ was 62.5%. Combining QTe/RR ≥ 0.210 with NSVT+ or LVEF ≤ 35%, the sudden death rates were 62.5% or 66.7%. Combining QTp/RR ≥ 0.190 with NSVT+ or LVEF ≤ 35%, the sudden death rates were 66.7% or 61.5%. Combining QTe/RR ≥ 0.210 or QTp/RR ≥ 0.190 with NVST+ and LVEF ≤ 35%, the sudden death rates were 77.8% or 70.0%.

CONCLUSIONS: High QT/RR slope is a risk factor for sudden death of DCM patients. QT/RR slope is a useful predictor for sudden death in DCM patients either independently or combined with NSVT or LVEF.