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

Sequential Atrioventricular Pacing in Patients With Hypertrophic Cardiomyopathy: An 18-year Experience

INTRODUCTION AND OBJECTIVES

Controversy persists regarding the role of sequential atrioventricular pacing in patients with obstructive hypertrophic cardiomyopathy and disabling symptoms. The aim of this study was to evaluate the effect of pacing on symptoms, dynamic gradient, and left ventricular function in patients with hypertrophic cardiomyopathy.

METHODS

From 1991 to 2009, dual-chamber pacemakers were implanted in 82 patients with obstructive hypertrophic cardiomyopathy and disabling symptoms despite optimal medical therapy. Sequential pacing was performed with a short atrioventricular delay. Clinical and echocardiographic parameters were measured before and immediately after implantation and after a long follow-up (median, 8.5 years [range, 1-18 years]).

RESULTS

The New York Heart Association functional class was immediately reduced after pacemaker implantation in 95% of patients (P < .0001), and this improvement was maintained until the final follow-up in 89% (P = .016). The gradient was significantly reduced after implantation (94.5 ± 36.5 vs 46.4 ± 26.7mmHg; P < .0001) and at final follow-up (94.5 ± 36.5 vs 35.9 ± 24.0mmHg; P < .0001). Mitral regurgitation permanently improved in 52% of the patients (P < .0001). There were no differences in ventricular thickness or diameters, ejection fraction, or diastolic function.

CONCLUSIONS

Sequential pacing in selected patients with obstructive hypertrophic cardiomyopathy improves functional class and reduces dynamic gradient and mitral regurgitation immediately after pacemaker implantation and at final follow-up. Prolonged ventricular pacing has no negative effects on systolic or diastolic function in these patients.

Does pacemaker implantation provide long-term benefits in severe obstructive hypertrophic cardiomyopathy?

INTRODUCTION AND OBJECTIVES

About 25% of patients with obstructive hypertrophic cardiomyopathy (HCM) remain symptomatic despite optimal medical treatment. Some may benefit from pacemaker implantation. The aim of this study was to determine the effect of pacemaker implantation on the left ventricular outflow tract (LVOT) gradient, the maximum thickness of the left ventricle, and functional capacity.

METHODS

In total, 72 patients with obstructive HCM and incapacitating symptoms underwent pacemaker implantation. Clinical examination, echocardiography (in 61 patients) and treadmill testing (in 34 patients) were performed before and after implantation.

RESULTS

Subjective functional capacity, as assessed using the New York Heart Association (NYHA) classification, improved in 43.1% of patients, but treadmill testing showed no change. There were significant reductions in subaortic gradient, from a median of 87.0 mmHg (interquartile range [IQR] 61.5-115.2 mmHg) to 30.0 mmHg (IQR 18.0-54.5 mmHg; P< .001), and maximum left ventricular thickness, from 22.1+/-4.5 mm to 19.8+/-3.6 mm (P=.001). Univariate analysis identified two factors associated with clinical improvement: female sex (odds ratio [OR]=3.43; P=.020) and functional class III/IV (OR=4.17; P=.009). On multivariate analysis, only functional class III/IV remained a significant predictor (OR=3.12; P=.048).

CONCLUSIONS

In patients with obstructive HCM and incapacitating symptoms, pacemaker implantation reduced the LVOT gradient and the maximum left ventricular thickness, but only 43.1% of patients experienced clinical improvement. The only factor predictive of improvement was advanced NYHA functional class.

Remodelado ventricular izquierdo tras ablación septal percutánea con alcohol en pacientes con miocardiopatía hipertrófica obstructiva: estudio ecocardiográfico

INTRODUCTION

In patients with hypertrophic obstructive cardiomyopathy, obstruction in the left ventricular outflow tract may generate more hypertrophy. Our aim was to evaluate the impact of reducing ventricular outflow tract obstruction on left ventricular hypertrophy and remodeling after alcohol septal ablation.

PATIENTS AND METHOD

20 patients with hypertrophic obstructive cardiomyopathy who underwent alcohol septal ablation were included. Doppler echocardiography was performed in all patients at baseline, immediately after alcohol septal ablation, and at 3 and 12 months' follow-up. Left ventricular diameters and wall thickness and pressure gradients in the ventricular outflow tract were determined.

RESULTS

Immediately after alcohol septal ablation, ventricular outflow tract pressure gradient decreased from 63.0 27.7 to 28.2 24.7 mmHg (p < 0.001), without significant changes in left ventricular dimensions. However, after 12 months we observed an increase in left ventricular end-diastolic (from 47.1 4.9 to 50.8 4.5 mm) and end-systolic diameter (from 27.1 3.0 to 33.7 4.6 mm), as well as a reduction in septal (from 19.5 4.0 to 15.5 2.7 mm) and posterior wall thickness (from 14.0 2.2 to 12.9 1.3 mm) (p < 0.01 in all cases). Left ventricular end-diastolic and end-systolic volumes increased (from 106.4 26.9 to 123.1 28.7 ml and from 50.2 17.3 to 56.7 18.3 ml, respectively, p < 0.01 in both cases), without changes in left ventricular ejection fraction. The reduction in ventricular outflow tract pressure gradient at 12 months' follow-up correlated significantly with the increase in left ventricular end-systolic diameter (r = 0.63; p < 0.01).

CONCLUSIONS

In patients with hypertrophic obstructive cardiomyopathy who underwent alcohol septal ablation, relief of ventricular outflow tract obstruction is associated with an increase in left ventricular chamber diameters and volume. These findings suggest that middle- and long-term ventricular remodeling and regression of hypertrophy occur in these patients, which may contribute to their clinical improvement.