Feasibility and safety of early exercise testing using the Bruce protocol after acute myocardial infarction.

Abstract

To assess the feasibility and safety of exercise testing (ET) using a Bruce protocol (BPR) within three days of an acute myocardial infarction (AMI) with the data obtained from a prospectively managed database. Exercise testing after AMI is usually done between days 4 and 6 and often using a "low-level" protocol. Earlier testing with BPR may allow for efficient triage. Patients were considered for early ET when off intravenous nitroglycerine with no rest angina, uncontrolled cardiac failure or arrhythmias. Of 300 consecutive AMI patients who underwent an ET, 216 (72.0%; M = 163, F = 53; age mean 59 +/- 0.8 SEM, range 34 to 83 years) had ET within three days of admission. There were 124 (57%) negative, 56 (26%) positive and 36 (17%) indeterminate tests. The maximum heart rate achieved was 116 +/- 1 beats/min (range 64 to 163), which was 72.2 +/- 0.8% of predicted maximum (86.6% on beta-adrenergic blocking agents at ET; exercise duration = 6.7 +/- 0.2 min). Reasons for termination: maximum effort-89 (41%); low-level test target (stage III/IV of BPR)-63 (29%); positive ST segment change-19 (9%); severe chest pain-12 (5.5%); reaching 90% predicted maximum heart rate-6 (3%); nonsustained ventricular tachycardia-1 (0.5%); other-26 (12%). Fourteen (6.5%) patients had minor complications (i.e., drop in systolic pressure, chest pain >5 min) with no cardiac arrests, AMIs or deaths. After the ET, 87 (40%) patients were discharged the same day, 73 (34%) the next day. The majority of ETs after an AMI can be done using the Bruce protocol within three days of admission with a very low incidence of complications. This can lead to early triage and potential cost savings.