[Dipyridamole-echocardiography and thallium exercise myocardial scintigraphy in the diagnosis of obstructive coronary or microvascular disease in hypertensive patients with left ventricular hypertrophy and angina].

BACKGROUND

Hypertensive patients with left ventricular hypertrophy can be affected with angina pectoris for significant epicardial coronary stenosis or microvascular disease with normal coronarography. Exercise-electrocardiography test is positive in both conditions. The aim of the present study was to assess the accuracy of dipyridamole-echocardiography test and thallium exercise myocardial scintigraphy in the diagnosis of epicardial coronary stenosis or microvascular disease in hypertensive patients with left ventricular hypertrophy and angina pectoris.

METHODS

Forty-two hypertensive patients (22 males, age 40-76 years, mean 58.6 +/- 10.1), with left ventricular hypertrophy, typical angina pectoris, ischemia that can be induced by exercise-electrocardiography test, without previous myocardial infarction, myocardial revascularization or diabetes mellitus, underwent dipyridamole-echocardiography test, thallium exercise myocardial scintigraphy and coronarography. Dipyridamole-echocardiography test was performed with dipyridamole (0.56 mg/kg over 4 minutes, followed by 0.28 mg/kg from the 8th to the 10th minute) + atropine (1 mg from the 12th to 15th min.) and was positive for a transient dyssynergy of contraction of at least 2 myocardial segments; the left ventricle was divided into 16 segments. SPECT thallium myocardial scintigraphy was performed after bicycle exercise and then three hours later, and it was positive for reversible uptake defects of at least 2 segments with a 22-segment model. Coronarography was performed with Judkin's technique and was positive if at least one large epicardial vessel was narrowed by more than 50%.

RESULTS

Coronarography: normal in 25 cases (59.5%, 8 males), pathologic in 17 (40.5%, 14 males): left main coronary artery in 1 (5.9%), three vessels in 5 (29.4%), two vessels in 3 (17.7%), 1 vessel in 8 (47%). Dipyridamole-echocardiography-test: positive in 15 cases (35.7%), negative in 27 (64.3%); sensitivity 88.2%, specificity 100%, diagnostic accuracy 95.2%, positive predictive value 100%, negative predictive value 92.6%. Thallium exercise myocardial scintigraphy: positive in 30 cases (71.4%), negative in 12 (28.6%); sensitivity 100%, specificity 48%, diagnostic accuracy 69%, positive predictive value 56.7%, negative predictive value 100%.

CONCLUSIONS

Dipyridamole-echocardiography test has higher diagnostic accuracy and when positive, it predicts significant epicardial coronary stenosis. It can be less sensitive in one-vessel patients (2 false negatives were stenosis 75% of left anterior descending and 60% of 1st diagonal). Thallium exercise myocardial scintigraphy is complementary because when negative, it excludes epicardial coronary stenosis and confirms microvascular disease. In hypertensive patients with left ventricular hypertrophy and suspected angina pectoris, the following flow-chart may be proposed: the first test is exercise-electrocardiography test. Only those who are positive at low-to-intermediate workload then undergo dipyridamole-echocardiography test. Those who are positive in this then undergo coronarography, while the negative ones undergo thallium exercise myocardial scintigraphy. Those who are positive at thallium exercise myocardial scintigraphy perform the coronarography, while cases with negative results do not undergo further diagnostic tests since they are affected with microvascular disease.