USEFULNESS OF LABORATORY MENTAL STRESS TEST IN PATIENTS WITH STABLE CORONARY-ARTERY DISEASE

Background and hypothesis: Many episodes of ischemia in daily life are silent occurring during sedentary activities and may be related to me ntal stress. In 35 patients with stable angina and positive exercise t est awaiting bypass surgery, we investigated whether laboratory mental stress tests would trigger ischemia of a comparable severity to that occurring in daily life and attempted to elucidate some of the underly ing mechanisms. Methods: All patients underwent exercise testing, pers onality assessment, 2-day Holter monitoring, and laboratory mental str ess tests while on their usual medications. Results: Only four patient s (12%) had positive mental stress test (ST depression greater than or equal to 0.1 mV). All episodes were silent and usually associated wit h fast heart rate (> 90 beats/min). In contrast, ambulatory ischemia w as common (average duration of 51 min per 24 h), and at least one epis ode was recorded in 27 patients (77%) including the ii with positive t est. Patients with positive mental stress test had a higher heart rate during testing (124 +/- 24 vs. 86 +/- 16 beats/min, p < 0.01), and a shorter exercise time and time to 1 mm ST depression on cycle ergometr y than those with negative mental stress test. None of the four patien ts were on beta blockers. There was no difference in personality inven tory between the two groups. Comparisons between patients with and wit hout positive mental stress test revealed no difference in the duratio n and frequency of ambulatory ischemia, or in the occurrence of silent ischemia. However, the heart rate at onset of ambulatory ischemia ten ded to be higher in the patients with positive mental stress test (96 +/- 9 vs. 62 +/- 43, p = 0.07). Further subgroup analysis in patients without beta blockers (4 mental stress test positive and 18 negative) showed similar results. Conclusions: Laboratory mental stress test is a weak inducer of ischemia detected by electrocardiographic monitoring in patients with frequent ambulatory ischemia. Wall motion evaluation during mental stress test may improve sensitivity. While larger scale studies may determine its clinical role, the present study illustrate d that patients with heightened heart rate response to mental stress w ere identified in whom beta blockers could be the drug of choice.