Does pacemaker implantation provide long-term benefits in severe obstructive hypertrophic cardiomyopathy?
OBJECTIVE
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.
Sandín
Míriam
M
Servicio de Cardiología. Hospital General Universitario de Alicante, Alicante, España.
Marín
Francisco
F
Cambronero
Francisco
F
Climent
Vicente
V
Caro
César
C
Martínez
Juan Gabriel
JG
Honrubia
Antonio García
AG
García Alberola
Arcadio
A
de la Morena
Gonzalo
G
Valdés
Mariano
M
Sogorb
Francisco
F
D002312:Cardiomyopathy, Hypertrophic / Q000628:therapy*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013997:Time Factors