The “Myth” of the False Positive Stress Echo

Abstract

It has been more than 25 years since the first reports of the use of echocardiographic imaging in conjunction with stress testing for the diagnosis of coronary artery disease. Since that time, both radionuclide and echocardiographic stress testing have become a routine part of the evaluation of patients with known or suspected coronary artery disease. Previous studies have indicated sensitivity and specificity of stress echocardiography in the range of 70% to 90%, compared with coronary angiography as a gold standard, for detecting hemodynamically significant obstructions. 1,2 These differences have been explained by a variety of factors, including the extent of disease, reader experience, heart rate obtained during stress, concurrent medications, and other factors. Patients with abnormal results on stress exams (based on the development of new wall motion abnormalities), but with subsequent findings on coronary angiography indicating no significant coronary stenosis, are said to have had ‘‘false-positive’’ results. Echocardiography has been reported to have higher specificity and fewer ‘‘false-positive’’ results than other imaging modalities. Traditionally, these patients with ‘‘false-positive’’ examinations have been treated as if they had no significant coronary artery disease risk and are often dismissed from the care of cardiovascular specialists. The study by From et al 3 in this issue of JASE challenges the concept of ‘‘false-positive’’ stress echocardiographic results. The authors evaluated a consecutive group of 1477 patients with abnormal stress echocardiographic results who underwent coronary angiography. Of this group, approximately two thirds had significant coronary artery disease. The remaining patients had so-called false-positive results, because angiography demonstrated <50% stenosis. Despite this, during an average follow-up of 2.4 years, there was no significant difference in the overall death rate between those with and without 50% luminalnarrowingonangiography.Onemightconclude thatin lightof the findings, patients with ‘‘false-positive’’ stress echocardiographic results should receive the same intensive risk factor modification and careful follow-up as patients with ‘‘true-positive’’ stress echocardiographic results (ie, confirmed by angiography). What are the possible explanations for these findings, and what are the potential implications?