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Updated: Jun 3, 2026
Translational Rabbit Model of Chronic Cardiac Pacing
Published on: January 6, 2023
Initial experience of a cohort of patients with hypertrophic cardiomyopathy undergoing biventricular pacing
Christopher A Rinaldi1, Senthil Kirubakaran, Clifford A Bucknall
1Cardiothoracic Dept Guys and St Thomas NHS Trust.
Insights
Biventricular pacing offers short-term benefits for some hypertrophic cardiomyopathy patients, reducing outflow tract gradients. However, long-term outcomes varied, with some patients experiencing deterioration or complications.
Area of Science:
- Cardiology
- Cardiac Electrophysiology
Background:
- Hypertrophic cardiomyopathy (HCM) is a condition where dual chamber pacing can improve symptoms and reduce left ventricular outflow tract (LVOT) gradients.
- However, the effectiveness of biventricular (BIV) pacing in symptomatic HCM patients requires further investigation.
Purpose of the Study:
- To investigate the use and efficacy of biventricular (BIV) pacing in symptomatic patients with hypertrophic cardiomyopathy (HCM).
Main Methods:
- Eight symptomatic HCM patients underwent BIV pacing, with ventricular leads in the right ventricle (RV) and coronary sinus.
- Short-term effects were assessed via echocardiography, while symptoms and exercise tolerance were evaluated after one month of pacing.
- Long-term follow-up data was collected for up to 5 years.
Main Results:
- BIV pacing significantly reduced QRS duration compared to RV pacing.
- LVOT gradients decreased with both RV pacing and BIV pacing, with BIV pacing showing a greater reduction.
- Six out of eight patients experienced improved exercise time, with three benefiting from RV pacing and three from BIV pacing.
Conclusions:
- Biventricular pacing demonstrated short-term advantages over RV pacing alone in select HCM patients, particularly in reducing LVOT gradients.
- Long-term outcomes were mixed, with one patient dying, another experiencing LV dilatation, and a third requiring system explantation.
Background:
Dual chamber pacing improves functional status and reduces left ventricular outflow tract gradients in some, but not all patients with hypertrophic cardiomyopathy (HCM) by altering ventricular depolarisation. We investigated the use of biventricular (BIV) pacing in symptomatic patients with HCM.
Method:
8 patients aged 58±7yrs with symptomatic HCM underwent BIV pacing. 5 patients had LVOT gradients >30mmHg. Ventricular electrodes were placed in the right ventricle (RV) and a branch of the coronary sinus. An atrial electrode was inserted to achieve BIV pacing with a short AV delay. The short-term effects of different pacing modalities were assessed using 2-D and Doppler echocardiography. Symptoms and exercise tolerance were assessed after a month of each pacing mode. Long-term follow up data was available for 5 years.
Results:
Baseline EF was 67±14% and mean QRS duration was 132±26msecs. BIV pacing reduced QRS duration compared to RV pacing (129±46 vs. 205±54msecs, p<0.005). Five of the seven patients had baseline LVOT gradients (mean 67±25mmHg) that decreased to 41±15mm Hg with RV pacing (p<0.01) and 25±15mmHg with BIV pacing (p<0.005). Improvements in exercise time with active pacing occurred in six out of eight patients (75%), three (37.5%) had optimal exercise times with RV pacing and three with BIV pacing. Of the three patients with short term improvements with BIV pacing, one died 4 years post implant, one deteriorated with LV dilatation and one had the system explanted for infection.
Conclusion:
BIV pacing showed short-term beneficial effects in some patients over and above RV pacing alone.
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