ROLE OF MYOCARDIAL CONTRAST ECHOCARDIOGRAPHY DURING NONSURGICAL SEPTAL REDUCTION THERAPY FOR HYPERTROPHIC OBSTRUCTIVE CARDIOMYOPATHY

Objectives. This study was undertaken to evaluate the ability of myoca rdial contrast echocardiography (MCE) to guide the targeted delivery o f ethanol during nonsurgical septal reduction therapy (NSRT) and to as sess the relation between the MCE risk area and infarct size determine d by enzymatic and radionuclide methods. Background. NSRT with intraco ronary ethanol is a new promising treatment for patients with hypertro phic obstructive cardiomyopathy (HOCM). Proper localization and quanti fication of the septal infarct before ethanol injection are highly des irable. MCE can provide accurate delineation of the vascular territory of the coronary arteries. Methods. Twenty-nine patients,vith HOCM and maximal medical therapy underwent NSRT. The left ventricular outflow tract (LVOT) gradient by Doppler echocardiography at baseline was 53 /- 16 mm Hg (mean a SD). Before NSRT, MCE was performed in all patient s with intracoronary sonicated albumin (Albunex). Diluted sonicated al bumin (Albunex) was selectively injected into the septal perforator ar teries during simultaneous transthoracic imaging. Immediately after MC E, ethanol was injected into the same vessel. Plasma total creatine ki nase (CK), total CK-MB fraction and CK MB fraction subforms were measu red at baseline and serially for 36 h. Results. LVOT gradient decrease d to 12 +/- 6 mm Hg (p < 0.001) after NSRT. Accurate mapping of the va scular beds of the septal perforators was successfully attained in all patients by MCE. Furthermore, the MCE risk area correlated well with peak CK (r = 0.79, p < 0.001). Six weeks after NSRT, 23 patients under went myocardial perfusion studies performed with single photon emissio n computed tomography (SPECT). Mean SPECT septal perfusion defect size involved 9.5 +/- 6% of the left ventricle and correlated well with MC E area (r = 0.7), with no statistically significant difference between the risk area estimated by MCE and that by SPECT. Conclusions. Estima tion of the size of the septal vascular territory,vith MCE is accurate , safe and feasible in essentially all patients during NSRT. MCE can d elineate the perfusion bed of the septal perforators and can predict t he infarct size that follows ethanol injection.