[Perception threshold of angina and transient myocardial ischemia in ambulatory electrocardiography].

AIM OF THE STUDY

We studied the predictive value of prolonged angina perception threshold in identifying patients with stable coronary artery disease at risk of silent myocardial ischemia during daily life.

METHODS AND RESULTS

71 patients with documented coronary artery disease (previous myocardial infarction or stenotic lesion > 60% at angiography) underwent a symptom-limited exercise test and out-of-hospital Holter monitoring after drug withdrawal. A second exercise test was performed before disconnecting the dynamic EKG in order to validate the ST-depression recorded during ambulatory monitoring. 23 patients (32.4%) (Group A) had angina perception threshold > 60 sec after onset of ischemia (ST > 1 mm), while in 48 (67.7%) the delay in the perception of angina was shorter than 60 sec (Group B). The demographic, clinical and angiographic variables did not influence the angina perception threshold; however, this parameter was the most powerful predictor of ambulatory ischemia among the two groups (4.8 vs 2.8 p < 0.02), and in particular of the painless episodes (3.8 vs 1.8 p < 0.002). Moreover, the silent ischemic time was longer in patients of group A (4362 vs 1774 sec p < 0.017). Finally, the event-free survival was similar in the two groups of patients during the 2 years of follow-up (cardiac death 1 vs 3, nonfatal myocardial infarction 1 vs 1, aorto-coronary bypass 2 vs 7, PTCA 2 vs 2, unstable angina 0 vs 2), total events 6 vs 15 p = ns.

CONCLUSIONS

These results demonstrate that the patients at risk for silent ischemia during ambulatory monitoring may be identified simply by evaluating their angina perception threshold during exercise test; however, silent ischemia does not have an adverse prognostic value.