Miocardiopatía hipertrófica obstructiva y estimulación secuencial auriculoventricular. Resultados agudos y seguimiento a largo plazo. Siete años de experiencia

Abstract

Sequential pacing as a primary treatment for patients with severe hypertrophic obstructive cardiomyopathy is still under controversy. In this study we sought to evaluate the effects of pacing on left ventricular systolic and diastolic function, its repercussion on pathophysiology and the possible changes in clinical evolution and functional class in patients who didn't respond to medical therapy. Thirty-four patients with severe hypertrophic obstructive cardiomyopathy in functional class III-IV underwent evaluation. The mean age was 64 +/- 11 years. Sixty-two per cent were over 65. The study protocol included Holter monitoring, baseline echo-Doppler, during pacing, at 6 months and at the end of follow-up, and a complete catheterization and coronary angiography. Mean follow-up time was 36 +/- 20 month (range 6-74). In four patients sequential pacing was ineffective and the protocol had to be discontinued. Thirty patients received a permanent dual-chamber pacemaker and systolic and diastolic function were evaluated by hemodynamic, angiographic and eco-Doppler studies. Long-term stimulation reduced the subaortic gradient from 95 +/- 38 to 39 +/- 28 mmHg (p < 0.001), left ventricular systolic pressure from 207 +/- 38 to 164 +/- 30 mmHg (p < 0.001) and left ventricular end-diastolic pressure from 23 +/- 7 to 14 +/- 5 mmHg (p < 0.001), pulmonary capillary wedge pressure from 19 +/- 7 to 14 +/- 5 mmHg (p < 0.001), ejection fraction from 79 +/- 6 to 71 +/- 6% (p < 0.001) and mitral insufficiency. Diastolic function improved with an increase in early filling from 39 +/- 11 to 52 +/- 10% (p < 0.001) and E/A relation from 0.93 +/- 0.4 to 1.6 +/- 0.8 (p < 0.001), and a reduction in late filling from the left ventricle from 36 +/- 10% to 24 +/- 10% (p < 0.001). The speed of the E wave increased from 0.83 +/- 0.3 to 0.92 +/- 0.3 (p < 0.001) and we observed a reduction of the A wave from 93 +/- 0.3 to 0.66 +/- 0.2 (p < 0.001), pressure-half time from 95 +/- 34 to 66 +/- 19 ms (p < 0.001) and we observed deceleration time from 320 +/- 90 to 221 +/- 57 (p < 0.01). All patients have improved their functional class, allowing a reduction in pharmacological therapy. Two exitus of cardiological origin occurred. Sequential AV pacing in selected patients with severe hypertrophic obstructive cardiomyopathy can reduce subaortic gradient, pulmonary capillary wedge, left ventricular filling pressures and the severity of mitral regurgitation, and improve the markedly altered diastolic function. The significant symptomatic improvement allows a reduction in medical treatment. Thus, it represents a viable alternative to open-heart surgery, particularly in elderly patients, with lower morbidity and mortality rates.