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Feasibility and safety of early exercise testing using the Bruce protocol after acute myocardial infarction
M P Senaratne1, G Smith, S S Gulamhusein
1Division of Cardiac Sciences, Grey Nuns Hospital, Edmonton, Alberta, Canada. mano@ibm.net
Objective:
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.
Background:
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.
Methods:
Patients were considered for early ET when off intravenous nitroglycerine with no rest angina, uncontrolled cardiac failure or arrhythmias.
Results:
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.
Conclusions:
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.