Exercise above the ischemic threshold and serum markers of myocardial injury.

Full Abstract

BACKGROUND: Current guidelines for exercise training in coronary patients state that in the presence of exercise-induced ischemia, the heart rate during exercise should be at least 10 beats/min below the heart rate associated with an ST segment depression of 1 mm or greater. For patients with a relatively low ischemic threshold, this recommendation does not allow for a sufficient training stimulus. OBJECTIVE: To document the effects of a single session of exercise above the ischemic threshold on biochemical markers of myocardial injury in stable coronary patients with exercise-induced ischemia. Because creatine kinase (CK) and its MB isoenzyme (CK-MB) can both increase after exercise because of skeletal muscle injury, troponin T was also measured. METHODS: Twenty-one patients with documented coronary artery disease underwent two 20 min exercise sessions. The intensity of the first exercise training session was fixed at a heart rate below the ischemic threshold (ie, approximately 10 beats/min lower than the heart rate associated with the appearance of an ST segment depression of 1 mm or greater). The intensity of the second exercise session was fixed at a heart rate above the ischemic threshold. RESULTS: Blood test measurements at baseline, 6 h after and 24 h after the exercise sessions did not show any increase in total CK, CK-MB or troponin. The value of all measurements remained well below the lower limits associated with myocardial damage. CONCLUSION: A 20 min period of exercise above the ischemic threshold did not result in myocardial necrosis.

Author information

Author/s: Juneau, Martin (M); Roy, Nathalie (N); Nigam, Anil (A); Tardif, Jean Claude (JC); Larivée, Lucie (L);

Affiliation: Department of Medicine, Montreal Heart Institute, Montreal, Canada. martine.juneau(-atsign-)icm-mhi.org

Journal and publication information

Publication Type: Comparative Study; Journal Article; Research Support, Non-U.S. Gov't

Journal: The Canadian journal of cardiology (Can J Cardiol), published in Canada. (Language: eng)

Reference: 2009-Oct; vol 25 (issue 10) : pp e338-41

Dates: Created 2009/10/08; Completed 2009/10/27;

PMID: 19812806, status: MEDLINE (last retrieval date: 10/27/2009, IMS Date: )

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