Beta-blocker therapy for dynamic left ventricular outflow tract obstruction induced by exercise.
BACKGROUND
In patients who present with angina, dynamic left ventricular outflow tract obstruction may be responsible of symptoms. The aim of our study was to evaluate the effect of negative inotropic therapy on ventricular physiology and symptoms of patients with dynamic left ventricular outflow tract obstruction induced by exercise in the absence of hypertrophic cardiomyopathy.


METHODS
Seventy eight patients with symptoms of angina, normal exercise SPECT test and normal resting left ventricular systolic function were prospectively analysed with exercise echocardiography. Fifteen of them developed high outflow tract velocities (greater than 2.57 m/s) on effort. After treatment with bisoprolol (mean dose 6.9+/-3.5 mg) in these patients, symptoms and dynamic left ventricular outflow tract obstruction during exercise were re-evaluated.


RESULTS
After negative inotropic therapy, there was a significant reduction of 86.6% in the development of intracavitary gradient (15 to 2 patients). In all patients the left ventricular outflow tract velocities decreased (2.91+/-0.4 m/s to 1.92+/-0.46 m/s, p=0.001). However, the oxygen consumption during exercise was higher (7.3+/-1.7 METs to 8.5+/-1.8 METs, p=0.005), and symptoms improved significantly following therapy, with a reduction in mean NYHA class from 1.9+/-0.5 to 1.0+/-0.0 (p=0.001).


CONCLUSIONS
Negative inotropic therapy may represent a beneficial therapeutic approach in selected patients with dynamic left ventricular outflow tract obstruction induced by exercise and identified during exercise echocardiography.
Cabrera-Bueno
Fernando
F
Servicio de Cardiología, Hospital Clínico Universitario Virgen de la Victoria, Teatinos S/n, Colonia Santa Inés, 29010 Málaga, Spain. fonendo@hotmail.com
García-Pinilla
José Manuel
JM
Gómez-Doblas
Juan José
JJ
Montiel-Trujillo
Angel
A
Rodríguez-Bailón
Isabel
I
de Teresa-Galván
Eduardo
E
D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage*; D000787:Angina Pectoris / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000503:physiopathology; D017298:Bisoprolol / Q000008:administration & dosage*; D002312:Cardiomyopathy, Hypertrophic / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000503:physiopathology; D004452:Echocardiography; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D011446:Prospective Studies; D013599:Systole; D014694:Ventricular Outflow Obstruction / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000503:physiopathology
D000319:Adrenergic beta-Antagonists; D017298:Bisoprolol