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[Dual-chamber pacemakers in obstructive hypertrophic cardiomyopathy: gradient variation with stress echocardiography]
J G Martínez Martínez1, D Ortuño Alcaraz, F Marín Ortuño
1Servicio de Cardiología, Hospital General Universitario de Alicante.jgmm@ctv.es
Insights
Dual chamber pacemakers reduce obstructive hypertrophic cardiomyopathy gradients. However, dobutamine stress echocardiography reveals that obstruction and mitral valve issues reappear under stress.
Area of Science:
- Cardiology
- Cardiac Electrophysiology
- Echocardiography
Background:
- Obstructive hypertrophic cardiomyopathy (oHCM) with refractory symptoms can be treated with dual chamber pacemakers.
- Pacemaker implantation significantly decreases the left ventricular outflow tract (LVOT) gradient in oHCM patients.
Purpose of the Study:
- To evaluate LVOT gradient modifications using dobutamine stress echocardiography (DSE) after dual chamber pacemaker implantation in oHCM patients.
- To assess dynamic changes in systolic anterior motion of the mitral valve (SAM) and mitral regurgitation (MR) during DSE.
Main Methods:
- Ten oHCM patients with refractory symptoms received dual chamber pacemakers.
- Dobutamine stress echocardiography was performed, assessing LVOT gradient, SAM, and MR severity.
- Infusion rates ranged from 10 to 40 mcg/kg/min in 3-minute intervals.
Main Results:
- Pacemaker implantation reduced the mean LVOT gradient from 90 ± 15 mmHg to 20 ± 10 mmHg (p < 0.001).
- DSE increased the LVOT gradient to 101 ± 13 mmHg (p < 0.001).
- SAM and MR worsened significantly during DSE, appearing in all patients.
Conclusions:
- Dual chamber pacing effectively reduces resting LVOT gradient in oHCM.
- Dobutamine stress echocardiography unmasks dynamic obstruction and mitral valve dysfunction, indicating persistent or inducible hemodynamic compromise.
Introduction:
Permanent cardiac pacing with a dual chamber pacemaker has become a valid alternative in treatment of patients with obstructive hypertrophic cardiomyopathy and refractory symptoms to pharmacological treatment, with a significant decrease of left ventricular outflow tract gradient.
Aim:
To assess any modification of the gradient with dobutamine stress echocardiography.
Patients And Methods:
We study 10 patients with obstructive hypertrophic cardiomyopathy and angina and/or dyspnea refractory to customary pharmacological treatment. A dual chamber pacemaker had been implanted 3-6 months previously. A dobutamine stress echocardiography was performed, beginning with a 10 microgram/kg/min infusion, with increases of 10 micrograms each 3 minutes until a maximum of 40. Modification of subaortic gradient, severity of systolic anterior motion of mitral valve (SAM, degree 0-3/3) and severity of mitral regurgitation (degree 0-4/4) were assessed.
Results:
Subaortic gradient decreased in all patients after pacemaker implantation (90 +/- 15 vs 20 +/- 10 mmHg; p < 0.001). With stress echocardiography the gradient increased in all patients (20 +/- 10 to 101 +/- 13 mmHg; p < 0.001). After implant there were only two patients with a +1 SAM, while during stress echocardiography SAM developed in all patients in +2 or +3 degree. Three patients had +1 mitral regurgitation after pacemaker implantation but during stress echocardiography 2-4/4 mitral regurgitation developed in all patients.
Conclusions:
Permanent dual chamber pacing decreased left ventricular outflow tract gradient in patients with obstructive hypertrophic cardiomyopathy, but during dobutamine stress echocardiography obstruction echocardiographic signs appeared.