Correction of false positive posterior wall ischemia in myocardial scintigraphy by stress echocardiography

Stress echocardiography has developed as a sensitive and specific tool to diagnose coronary heart disease (CHD). Diagnostic sensitivity for myocardial scintigraphy is high too, but artifactual tracer defects in the posterior wall reduce specificity for diagnosing CHD. The aim of this study was to compare the two methods with special interest to posterior wall ischemia. We examined 40 patients with suspected CHD. Because of inconclusive results in exercise ECG they all underwent myocardial scintigraphy. In 21 patients posterior wall ischemia was suspected. These 21 patients were selected for further diagnosis with stress echocardiography and coronary angiography and retrospective analysis of all data. Stress echocardiography and myocardial scintigraphy were performed with combined stress: physical exercise preceded by iv dipyridamole for stress echocardiography and myocardial scintigraphy with 99 mTc-tetrofosmin-SPECT in a 2-day protocol and examination in supine position. Coronary angiography was performed within 60 days after stress echocardiography and myocardial scintigraphy respectively. Results were as follows: much higher accuracy of combined stress in stress echocardiography and myocardial scintigraphy for diagnosing CHD than submaximal ECG; comparable sensitivity of stress echocardiography and myocardial scintigraphy in combined stress with about 90%; much higher accuracy for diagnosing CHD for stress echocardiography vs myocardial scintigraphy with a specificity of about 90% for stress echocardiography compared to 50-60% for myocardial scintigraphy and a positive predictive value of about 90% for stress echocardiography compared to 66% in myocardial scintigraphy - especially due to false positive posterior wall ischemia in myocardial scintigraphy.