"Warm-up" phenomenon detected by electrocardiographic ambulatory monitoring in adult and older patients.
OBJECTIVE
Inducing tolerance to myocardial ischemia by repeated brief episodes of ischemia has been called "ischemic preconditioning." "Warm-up" phenomenon refers to patients with coronary heart disease improving performance after a first exertion and may represent a clinical counterpart to ischemic preconditioning. The goal of this study was to assess whether the severity of myocardial ischemia would be attenuated by two repeated walking-induced ischemic episodes in adult and older patients.


METHODS
Thirty-eight adults (51 +/- 5 years) and 39 older patients (76 +/- 4 years) with stable angina and angiographic evidence of coronary stenosis.


METHODS
Holter monitoring was performed in adult and older patients walking on two consecutive occasions, with a 5-minute rest between walks, a distance known to have previously caused myocardial ischemia.


RESULTS
Computer-assisted analysis recorded by ambulatory Holter monitoring revealed that the mean maximal ST-segment depression (P < .001) and ischemia duration decreased (P < .001), whereas the ischemic threshold increased (P < .001), from the first to the second walk in the adult but not in the older group.


CONCLUSIONS
Myocardial ischemia is attenuated and ischemic threshold is increased between two brief ischemic episodes in adult but not in older patients. These results indicate that the "warm-up" phenomenon, involved in increasing myocardial ischemic tolerance, is absent in the aging heart.
Napoli
C
C
Dipartimento di Medicina Clinica e Sperimentale, Facoltà di Medicina e Chirurgia, Università degli Studi di Napoli Federico II, Naples, Italy.
Liguori
A
A
Cacciatore
F
F
Rengo
F
F
Ambrosio
G
G
Abete
P
P
D000368:Aged; D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D000787:Angina Pectoris / Q000503:physiopathology*; D002908:Chronic Disease; D015716:Electrocardiography, Ambulatory / Q000379:methods; D005260:Female; D006801:Humans; D019157:Ischemic Preconditioning, Myocardial / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012815:Signal Processing, Computer-Assisted; D016138:Walking / Q000502:physiology*