Characteristics and prognostic importance of ST-segment elevation on Holter monitoring early after acute myocardial infarction

The correlation between episodes of ST-segment elevation on Holter monitoring, clinical characteristics, left ventricular function, exercise testing, and long-term prognosis was determined in 123 consecutive patients 55 ± 8 years old (mean ± SD) with a first acute myocardial infarction (AMI). During 36 hours of Holter recording 11 ± 5 days after AMI, 11 patients (9%) had 91 episodes of ST-segment elevation (group 1), whereas 112 patients had no such episodes (group 2). Most episodes of ST-segment elevation occurred in leads with pathologic Q waves or small, indistinct R waves. Large, anterior Q-wave AMIs were more prevalent in group 1 than in group 2, and in-hospital heart failure also occurred more frequently in group 1 patients (82% vs 23%; p < 0.0005). Regional and global left ventricular function was reduced in group 1 compared with group 2: ejection fraction 33 ± 11% vs 50 ± 11% (p = 0.0001). All episodes of ST-segment elevation were asymptomatic and did not correlate with different indicators of myocardial ischemia. Indeed, exercise-induced ST-segment depression was more prevalent in group 2 than in group 1: 57 vs 18% (p < 0.035). Over a mean of 5 years (range 4 to 6) of follow-up, an association between episodes of ST-segment elevation on Holter monitoring and (1) cardiac death (Kaplan-Meier analysis; p < 0.005), and (2) cardiac death and nonfatal reinfarction (Kaplan-Meier analysis; p < 0.025) was found. If, however, the symptomatic need for coronary revascularization was included as an end point, no association between episodes of ST-segment elevation and long-term outcome could be demonstrated (Kaplan-Meier analysis; p = NS).