June 19, 2015

Comparison of the Effects of Epicardial and Endocardial Cardiac Resynchronization Therapy on Transmural Dispersion of Repolarization

Q: What is the clinical evidence from this study?

Study design: Observational. Population: Failed epicardial CRT due to coronary sinus lead dislodgement (n=7). Intervention: Transseptal endocardial biventricular pacing vs. Epicardial biventricular pacing. Primary outcome: Transmural dispersion of repolarization (TpTe and TpTe/QT ratio) (p=0.01).

Resultado clave

Transseptal endocardial biventricular pacing significantly reduced transmural dispersion of repolarization compared to epicardial pacing (change in TpTe -12.6 ms vs 17.1 ms, P=0.01).

Puntos clave

The study aims to compare the effects of epicardial and endocardial cardiac resynchronization therapy on parameters of myocardial repolarization.
Seven patients with coronary sinus lead dislodgement underwent implantation of endocardial left ventricle leads.
Electrocardiograms were analyzed before and after epicardial and endocardial pacing.
Markers of transmural dispersion of repolarization were measured and compared.
No significant differences were found in baseline QRS duration, TpTe values, or TpTe/QT ratios between pacing methods.
Epicardial pacing resulted in a significant increase in TpTe (17.1 ms vs -12.6 ms, P = 0.01) compared to endocardial pacing.
The TpTe/QT ratio also increased significantly with epicardial pacing (0.03 vs -0.02, P = 0.04) compared to transseptal endocardial CRT.

Diseño del estudio

Tipo

Observational (n=7)

PICO estructurado

Does transseptal endocardial biventricular pacing reduce transmural dispersion of repolarization compared to epicardial pacing in patients receiving CRT?

Población

7 patients who had transseptal endocardial left ventricle (LV) lead placement, in whom epicardial CRT had failed due to coronary sinus (CS) lead dislodgement after successful implantation

Intervención

Transseptal endocardial biventricular pacing (LV endocardial leads implanted through the interatrial septum in a lateral position)

Comparador

Epicardial biventricular pacing (in the same patients prior to CS lead dislodgement)

Resultado

ECG markers of transmural dispersion of repolarization (TpTe and TpTe/QT ratio)surrogate

Transseptal LV endocardial pacing is associated with a significant reduction in transmural dispersion of repolarization compared to epicardial pacing, which may help reduce arrhythmias in CRT patients.

Resultado numérico

valor p: p=0.01

Resumen

BACKGROUND: Despite significant improvements in cardiac output and functional capacity with cardiac resynchronization therapy (CRT), incidence of sudden cardiac death still remains high. Reversal of physiological myocardial activation sequence during epicardial pacing increases the transmural dispersion of repolarization (TDR). The aim of this study was to compare the effects of endocardial and epicardial biventricular pacing on repolarization parameters in the same patient group. METHODS: Seven patients who had transseptal endocardial left ventricle (LV) lead placement, in whom epicardial CRT had failed due to coronary sinus (CS) lead dislodgement after successful implantation, were admitted to the study. LV endocardial leads were implanted through the interatrial septum in a lateral position. Electrocardiograms (ECGs) were scanned before and after successful epicardial and endocardial biventricular pacing and analyzed using digital calipers. ECG markers of TDR (TpTe and TpTe/QT ratio) were measured and compared. RESULTS: Baseline QRS durations (161.7 ± 15.9 ms vs 162.2 ± 17.8 ms, P = 0.95), TpTe values (107.1 ± 20.5 ms vs 108.5 ± 17.6 ms, P = 0.89), and TpTe/QT ratios (0.24 ± 0.05 vs 0.24 ± 0.03, P = 0.88) were similar before epicardial and endocardial CRT. QRS interval reduction was similar (-28.3 ± 11.6 ms vs -29.1 ± 11.4 ms, P = 0.89) in both groups. Compared to transseptal endocardial CRT, epicardial CRT was associated with a significant increase in TpTe (17.1 ± 19.5 ms vs -12.6 ± 18.9 ms, P = 0.01) and TpTe/QT ratio (0.03 ± 0.04 vs -0.02 ± 0.03, P = 0.04). CONCLUSION: Transseptal LV endocardial pacing is associated with significant reduction in TDR characteristics compared to epicardial pacing in CRT. Further studies are warranted to determine whether these effects may contribute to reduction of arrhythmias in patients with CRT.

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