Left ventricular systolic dysfunction during exercise and dobutamine stress in patients with hypertrophic cardiomyopathy

OBJECTIVES We sought to characterize stress-induced left ventricular systol ic dysfunction in patients with hypertrophic cardiomyopathy (HCM). BACKGROUNDS Myocardial ischemia and diastolic dysfunction occur in patients with HCM. We hypothesized that, in the setting of transient myocardial isc hemia, left ventricular systolic dysfunction occurs during exercise and dob utamine stress. METHODS We studied 39 patients with HCM but without obstructive symptoms at rest or coronary artery disease. A continuous ventricular function monitor equipped with cadmium telluride detectors (VEST) was used to evaluate left ventricular function during supine bicycle ergometer exercise. Dobutamine stress echocardiography (DSE) was also performed. The left ventricular ejec tion Fraction (LVEF) and regional wall motion were determined from echocard iographic images. RESULTS Changes in the LVEF correlated between exercise and dobutamine stre ss (r = 0.643, p < 0.0001). The LVEF decreased more than 5% at peak exercis e in 17 of patients (group IT), while the other patients had normal respons es (group I). New regional wall motion abnormalities during dobutamine infu sion were detected in 18 of 110 (16.4%) segments in group I and 42 of 85 (4 9.4%) segments in group II. Decreased or unchanged regional wall motion occ urred more frequently in hypertrophied segments than in nonhypertrophied se gments (p < 0.0001). There were significant inverse correlations between th e LVEF responses during both stresses and the number of abnormal segments n oted during dobutamine stress in all patients (VEST: p < 0.005; DSE: p < 0. 0005). Signs of left ventricular obstruction were observed in 11 of 39 pati ents during DSE. However, there was no significant correlation between the LVEF response and the dobutamine-induced left ventricular pressure gradient . CONCLUSIONS Exercise-induced systolic dysfunction occurred in 50% of patien ts with HCM. In these patients, regional wall motion abnormalities were pre sent in hypertrophied segments. (C) 2000 by the American College of Cardiol ogy.