UNSTABLE ANGINA - ROLE OF SILENT ISCHEMIA AND TOTAL ISCHEMIC TIME (SILENT PLUS PAINFUL ISCHEMIA), A 6-YEAR FOLLOW-UP

To assess the long-term prognostic significance of total ischemic time (silent plus painful ischemia) and silent ischemia in patients with unstable angina whose condition stabilized with medical treatment, 76 patients were studied. All patients underwent Holter ambulatory electrocardiographic (ECG) monitoring for greater-than-or-equal-to 48 h beginning within the 1st 12 h of the hospital stay. Forty-three patients (Group A) had a total ischemic time greater-than-or-equal-to 60 min, whereas 33 patients (Group B) had a total ischemic time < 60 min. More than 78% of the ischemic episodes in patients in Group A and 62% of those in Group B were silent (p < 0.05); nine patients in Group A and six in Group B had only silent episodes. Patients in Group A frequently showed three-vessel disease (65% vs. 18%, p < 0.01), angiographic findings of subtotal occlusion of the coronary arteries (TIMI grade I) (76.7% vs. 42.4%, p < 0.01) and ischemic alterations in the rest ECG (51.2% vs. 30.3%, p < 0.05). During a 6-year follow-up period, 15 patients in Group A and 8 in Group B experienced myocardial infarction (p < 0.05); 9 patients in Group A and 4 in Group B required coronary artery surgery (p < 0.05) and 10 patients in Group A and 4 in Group B died of cardiac causes (p < 0.01). Multivariate analysis showed three-vessel disease to be the most important predictor of cardiac mortality and morbidity (p = 0.025); it was followed in predictive power by a total ischemic time greater-than-or-equal-to 60 min and by left ventricular disfunction. The presence of silent ischemia was not shown to be an independent predictor of long-term morbidity and mortality. In conclusion, patients with unstable angina and a total ischemic time greater-than-or-equal-to 60 min frequently have silent ischemic episodes on Holter ECG monitoring, a greater extent of coronary atherosclerosis and ischemic alterations of the rest ECG. The long-term prognosis of patients with unstable angina whose condition stabilizes with medical treatment depends on the extent of coronary atherosclerosis and on the longer duration of total ischemic time but not on the presence of silent ischemia.