STRESS ECHOCARDIOGRAPHY USING ADENOSINE COMBINED WITH NITROGLYCERIN-DOBUTAMINE IN THE DETECTION OF VIABLE MYOCARDIUM IN PATIENTS WITH PREVIOUS MYOCARDIAL-INFARCTION

The aim of this study was to assess the value of adenosine (A) and the combination of nitroglycerin (N) with dobutamine (D) stress echocardi ography (SE) in the identification of viable myocardium. The clinical and electrocardiographic (EGG) effects of both tests were also evaluat ed. Fifty-two coronary artery disease patients, aged 56.4 +/- 8 years, with left ventricular dysfunction due to a previous myocardial infarc tion (mean ejection fraction: 49 +/- 8%) were included in the study. C ardiac catheterization was performed in all patients before A (140 mu g/kg/minute for five minutes) and the combination of N with D (5-10 mu g/kg/minute) stress echocardiography. On the echocardiogram, the left ventricle was divided into 16 segments and wall motion was graded sem iquantitatively from 1 (normal) to 4 (dyskinesia). The echocardiograph ic index was also estimated. A segment was considered viable during A infusion when resting asynergy showed deterioration of one grade or mo re. In contrast, segmental viability was considered to be present duri ng the combination of N with D infusion when resting asynergy showed i mprovement of one grade or more. A thallium 201 single photon emission computed tonography (SPECT) with reinjection was performed as referen ce standard for the identification of viable myocardium. Stress echoca rdiography during infusion of A was associated with short-duration ang ina attacks in 3 (5.8%) patients and transient complete atrioventricul ar (AV) block in 1 (1.9%), whereas during the combination of N with D infusion, 6 (11.5%) patients experienced ventricular bigeminy lasting for a short period. ST segment elevation greater than 1 mm was recorde d in those leads having a Q wave, in 19 (36.5%) patients. In 10 of the se 19 (52.6%), viable myocardium was present in SPECT, as it was in 33 patients (63.5%) having no ST segment elevation (P=NS). Of a total of 832 segments that were graded during A-SE, 276 exhibited resting asyn ergy and the remaining 556 had normal motion and thickening at rest. T he echocardiographic index during A infusion increased from 1.52 +/- 0 .22 to 1.71 +/- 0.24 (P < 0.001), whereas during D and N infusion it d ecreased from 1.53 +/- 0.31 to 1.30 +/- 0.42 (P < 0.001). With SPECT c onsidered as the gold standard for the identification of viable myocar dium, sensitivity, specificity, and positive and negative predictive v alues of A-SE in detecting viable myocardium were 54%, 86%, 65% and 80 %, respectively. The respective values for the combination of nitrogly cerin with D-SE were 91%, 89%, 78%, and 96%, respectively. Stress echo cardiography during A, and the combination of N with D, constitute saf e methods in the identification of viable myocardium. The detection of ST segment elevation in the ECG leads with a Q wave during the combin ed infusion of nitroglycerin and dobutamine is not related to the pres ence of viable myocardial tissue. The A-SE provide moderate diagnostic accuracy, while the combination of N with D during SE is much superio r in detecting viable myocardium.