[Predictive value of QT interval dynamicity for sudden death in patients with idiopathic dilated cardiomyopathy]
Ming-Wei Bao1, Tuan-Tuan Tan, Sheng-Bo Yu
1Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan 430060, China. sanko747@yahoo.com.cn
Insights
QT/RR slope is a significant predictor of sudden death in idiopathic dilated cardiomyopathy (DCM) patients. This metric, especially when combined with non-sustained ventricular tachycardia or reduced ejection fraction, improves risk stratification for sudden cardiac death.
Area of Science:
- Cardiology
- Electrophysiology
- Heart Failure Research
Context:
- Idiopathic dilated cardiomyopathy (DCM) poses a significant risk for sudden cardiac death (SCD).
- Accurate prediction of SCD is crucial for timely intervention in DCM patients.
- Existing risk stratification methods may not fully capture the dynamic electrical instability in DCM.
Purpose:
- To evaluate the predictive capability of QT interval dynamicity, specifically the QT/RR slope, for SCD in patients with DCM.
- To compare QT/RR slope with other established markers like left ventricular ejection fraction (LVEF) and non-sustained ventricular tachycardia (NSVT).
Summary:
- The study found significantly higher QT/RR slopes (both QTe/RR and QTp/RR) in DCM patients compared to controls.
- QT/RR slope, LVEF, and NSVT were significant predictors of SCD in DCM.
- Higher QT/RR slope values (≥0.210 for QTe/RR, ≥0.190 for QTp/RR) were associated with a significantly increased risk of SCD.
- Combining QT/RR slope with NSVT or reduced LVEF further enhanced SCD risk prediction.
Impact:
- QT/RR slope emerges as a valuable and independent predictor of SCD in DCM.
- Incorporating QT/RR slope into risk assessment models can improve the identification of high-risk DCM patients.
- This finding may lead to refined clinical guidelines for managing DCM and preventing SCD.
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.
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