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Effects of permanent dual chamber pacing on myocardial perfusion in symptomatic hypertrophic cardiomyopathy
J L Posma1, P K Blanksma, E E Van Der Wall
1Department of Cardiology, Thoraxcentre, University Hospital Groningen, Netherlands.
Insights
Dual chamber pacing improves angina in hypertrophic cardiomyopathy by reducing myocardial ischemia. This intervention led to more homogeneous myocardial perfusion and reserve, enhancing patient outcomes.
Area of Science:
- Cardiology
- Nuclear Medicine
- Biomedical Engineering
Background:
- Angina and myocardial ischemia are prevalent in hypertrophic cardiomyopathy (HCM).
- Dual chamber pacing has shown clinical benefits in HCM patients.
- The impact of pacing on myocardial perfusion in HCM requires further investigation.
Purpose of the Study:
- To evaluate the effects of permanent dual chamber pacing on absolute regional myocardial perfusion and perfusion reserve in patients with HCM.
- To compare myocardial perfusion parameters in HCM patients with and without pacing to healthy controls.
Main Methods:
- Six symptomatic HCM patients received dual chamber pacemakers.
- Myocardial perfusion and perfusion reserve were assessed using dynamic positron emission tomography (PET) with 13N-ammonia.
- Measurements were taken during sinus rhythm and 3 months post-pacing, with comparisons to 28 healthy volunteers.
Main Results:
- Pacing reduced anginal symptoms and intraventricular pressure gradient.
- Baseline myocardial perfusion was higher, and perfusion reserve lower in HCM patients versus controls.
- Pacing decreased resting myocardial blood flow but improved the homogeneity of stress perfusion and perfusion reserve.
Conclusions:
- Dual chamber pacing reduces resting and pharmacologically induced myocardial blood flow in HCM.
- While global perfusion reserve remained stable, pacing resulted in a more homogeneous distribution of myocardial perfusion reserve.
- Pacing offers a potential therapeutic strategy for improving myocardial perfusion abnormalities in HCM.
Objective:
Angina and the presence of myocardial ischaemia are common in hypertrophic cardiomyopathy. Dual chamber pacing results in clinical improvement in these patients. This study evaluates the effects of permanent dual chamber pacing on absolute regional myocardial perfusion and perfusion reserve.
Setting:
University hospital.
Patients And Design:
Six patients with hypertrophic cardiomyopathy and severe symptoms of angina received a dual chamber pacemaker. Absolute myocardial regional perfusion and perfusion reserve (dipyridamole 0.56 mg/kg) were measured by dynamic positron emission tomography with 13N-ammonia both during sinus rhythm and 3 months after pacemaker insertion. Results were compared with those from 28 healthy volunteers.
Results:
Pacing resulted in a reduction of anginal complaints and a reduction in intraventricular pressure gradient from 65 (SD 30) mm Hg to 19 (10) mm Hg. During sinus rhythm, baseline perfusion was higher in patients with hypertrophic cardiomyopathy than controls (184 (31) v 106 (26) ml/min/100 g, P < 0.01), and perfusion reserve was lower (1.6 (0.4) v 2.8 (1.0), P < 0.05). During pacing myocardial perfusion decreased to 130 (27) ml/min/100 g (P < 0.05), with variable responses in terms of perfusion reserve. Pacing caused a redistribution of myocardial stress perfusion and perfusion reserve. The coefficient of regional variation of myocardial stress perfusion decreased from 19.7 (7.0)% to 14.6 (3.9)% during pacing (12.9 (3.8)% in controls, P < 0.01). The coefficient of regional variation of perfusion reserve decreased from 16.7 (6.6)% to 11.4 (2.6)% during pacing (9.8 (4.1)% in controls, P < 0.01).
Conclusions:
Pacing caused a decrease of resting left ventricular myocardial blood flow and blood flow during pharmacologically induced coronary vasodilatation. Although global perfusion reserve remained unchanged, myocardial perfusion reserve became more homogeneously distributed.