Can prolonged exercise-induced myocardial ischaemia be innocuous?
OBJECTIVE
To evaluate the innocuousness of intense and prolonged exercise training above the threshold for myocardial ischaemia (1 mm ST-segment depression).


RESULTS
Twenty-two patients with ischaemic heart disease (IHD) were randomized to exercise training either at a target intensity that induced myocardial ischaemia (ischaemic group) or that adhered to current guidelines (control group). Training was progressively increased to 60 min under continuous electrocardiographic (ECG) monitoring. Cardiac troponin T (cTnT) was measured at various intervals. Ambulatory ECG monitoring was performed before and after 6 weeks of training and left ventricular function was evaluated in the ischaemic group after at least 6 weeks of training. The ischaemic group had myocardial ischaemia during the first 20, 40, and 60 min exercise sessions for 12.3 +/- 6.8, 29.0 +/- 12.9, and 49.8 +/- 2.2 min, respectively, with ST-segment depression ranging from 1.0 to 2.1 mm. No patient in either group demonstrated significant arrhythmias or increased cTnT. The ischaemic group had preserved left ventricular function.


CONCLUSIONS
In patients with IHD, prolonged and repeated ischaemic training sessions up to 60 min can be well tolerated without evidence of myocardial injury, significant arrhythmias, or left ventricular dysfunction.
Noël
Martin
M
Quebec Heart Institute, Laval Hospital, Laval University, 2725 Chemin Ste-Foy, Ste-Foy, Quebec, Canada G1V 4G5.
Jobin
Jean
J
Marcoux
Audrey
A
Poirier
Paul
P
Dagenais
Gilles R
GR
Bogaty
Peter
P
D000368:Aged; D001145:Arrhythmias, Cardiac / Q000209:etiology; D015716:Electrocardiography, Ambulatory; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D012307:Risk Factors; D020107:Troponin T / Q000378:metabolism; D018487:Ventricular Dysfunction, Left / Q000209:etiology / Q000503:physiopathology
D020107:Troponin T