Limitations of the exercise test as a screen for acute cardiac events in asymptomatic patients

The exercise stress test has been shown to have limited effectiveness when used to screen asymptomatic patients at risk for acute cardiac events, failing to detect many patients who have sudden death or myocardial infarction over long-term followup. The explanation may be found in studies that show that acute cardiac events frequently occur secondary to rapid transformation of an atherosclerotic lesion (secondary to plaque rupture and thrombosis), which may change a previously "non-critical" lesion into a total occlusion. Furthermore, the risk of plaque disruption may not be related to the preexisting severity of coronary artery stenosis, making it difficult to screen patients with techniques such as exercise stress testing, which rely on demonstrating myocardial ischemia or flow heterogeneity resulting from a flow-limiting lesion. Effective reduction in the incidence of sudden death will depend upon the development of diagnostic techniques that are sensitive to the presence of nonocclusive (as well as occlusive) coronary lesions and upon treatment that will prevent the cascade associated with rapid arterial occlusion.