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Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing
Published on: December 11, 2017
Biventricular pacing has an advantage over left ventricular epicardial pacing alone to minimize proarrhythmic
Masahide Harada1, Toshiyuki Osaka, Eriko Yokoyama
1Section of Arrhythmia, Division of Cardiology, Shizuoka Saiseikai General Hospital, Shizuoka, Japan.
Insights
Simultaneous biventricular pacing (BiVP) for cardiac resynchronization therapy (CRT) in heart failure patients minimally affects ventricular repolarization. Left ventricular epicardial pacing alone significantly increases repolarization dispersion, suggesting BiVP is safer for preventing arrhythmias.
Area of Science:
- Cardiology
- Electrophysiology
- Heart Failure Management
Background:
- Cardiac resynchronization therapy (CRT) using biventricular pacing is a key treatment for severe congestive heart failure (CHF).
- Left ventricular (LV) pacing alone has shown hemodynamic benefits, but its impact on ventricular repolarization and arrhythmogenic risk is less understood.
- Understanding repolarization changes is crucial for optimizing CRT and minimizing proarrhythmic effects.
Purpose of the Study:
- To compare the effects of different pacing strategies on ventricular repolarization in CHF patients.
- To evaluate ECG parameters including QTc, QTc dispersion, JTc, and Tc(peak-end) under various pacing conditions.
- To determine the arrhythmogenic potential of LV epicardial pacing versus biventricular pacing in the context of CRT.
Main Methods:
- Acute hemodynamic studies were conducted in 14 CHF patients scheduled for CRT.
- ECG parameters were analyzed during sinus rhythm (SR), right ventricular apex pacing (RV(end)P), LV epicardial pacing (LV(epi)P), and biventricular pacing (BiVP).
- Key repolarization intervals and dispersion measures were compared across pacing modes.
Main Results:
- LV(epi)P and RV(end)P significantly increased QTc intervals, while BiVP did not.
- LV(epi)P markedly increased QTc dispersion (66.5%) and Tc(peak-end) (55.4%) compared to SR.
- BiVP showed only modest increases in JTc (6.6%) and Tc(peak-end) (15.8%), indicating preserved repolarization.
- LV(epi)P significantly increased spatial dispersion of ventricular repolarization.
Conclusions:
- Left ventricular epicardial pacing alone causes substantial increases in ventricular repolarization dispersion in CHF patients.
- Simultaneous biventricular pacing (BiVP) demonstrates a significant advantage over LV epicardial pacing in minimizing proarrhythmic repolarization changes.
- BiVP may be a safer CRT strategy for reducing the risk of arrhythmias associated with pacing-induced repolarization abnormalities.
Introduction:
Cardiac resynchronization therapy (CRT) by simultaneous biventricular pacing is now widely accepted as a new therapeutic option for patients with severe congestive heart failure (CHF). Recent studies have shown comparable hemodynamic benefits of left ventricular (LV) pacing alone. The clinical usefulness of CRT, however, might be compromised by potential exaggeration of arrhythmogenic substrates through a modification of ventricular repolarization.
Methods And Results:
We compared ECG parameters during sinus rhythm (SR), atrioventricular synchronous pacing at the right ventricular apex (RV(end)P), at LV epicardium (LV(epi)P), and at both sites (BiVP) in acute homodynamic studies of 14 CHF patients scheduled for CRT (QRS duration = 144 +/- 23 msec, LVEF = 27 +/- 10%). The maximum rate of increase in LV pressure (LVdp/dt(max)) was decreased significantly during RV(end)P, whereas it was increased similarly during LV(epi)P and BiVP compared with SR. QTc was increased during RV(end)P (by 10.2%) and LV(epi)P (by 26.1%). QTc dispersion (QTc(max)-QTc(min) in the six precordial leads) was also increased during LV(epi)P (by 66.5%). These parameters were unaffected during BiVP. JTc was unchanged, and the interval from the peak to the end of the T wave (Tc(peak-end)) was increased slightly (by 19.3%) during RV(end)P. Both JTc and Tc(peak-end) were increased dramatically during LV(epi)P (by 18.2% and 55.4%, respectively), but increased only modestly during BiVP (by 6.6% and 15.8%, respectively).
Conclusions:
LV(epi)P causes much greater increase in spatial dispersion of ventricular repolarization than BiVP in CHF patients. BiVP may have a substantial advantage over LV(epi)P to minimize the proarrhythmic perturbation of ventricular repolarization in association with CRT.
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