OBJECTIVETo evaluate the safety and efficiency of the dobutamine stress echocardiography in patients with hypertrophic cardiomyopathy and estimate the difference between provokable obstruction and resting obstruction in these patients.

METHODSEchocardiography was performed in 22 patients with HCM (LVOTPG < 50 mm Hg at rest, 1 mm Hg = 0.133 kPa) at rest and at the end point of dobutamine stress. Dobutamine was administered via an infusion pump, starting at a dose of 5 microg x min(-1) x kg(-1) and increasing every 5 minutes by 5 microg x min(-1) x kg(-1) till the maximum dose of 20 microg x min(-1) x kg(-1). Fifty-seven patients with HCM (LVOTPG > 50 mm Hg at rest) were also studied at rest.

RESULTSIn these 22 patients, the mean maximum velocity of LVOT was 5.39 +/- 1.60 m/s, the mean maximum LVOTPG was 125.7 +/- 62.4 mm Hg at the end point of dobutamine stress and the mean dose of dobutamine was 13.90 +/- 6.85 microg x min(-1)xkg(-1). Sixteen patients evidenced positive stress results at the end point of dobutamine stress. The main difference between the provokable obstruction and resting obstruction was that in provokable obstruction patients, the SAM positive patients were fewer and the proportion of Maron II patients was higher (50%).

CONCLUSIONSDobutamine stress echocardiography was a safe and sensitive way for detecting patients with hypertrophic cardiomyopathy. Provokable obstruction patients had fewer SAM and higher proportion of Maron II.