Symptom-limited initial exercise induced the warm-up ischemia phenomenon by increasing the ischemic threshold on re-exercise (23.5 vs 20.3; P<0.0001), whereas lower intensity exercise did not.
Does the intensity of initial myocardial ischemia determine the induction of the warm-up ischemia phenomenon in patients with exertional myocardial ischemia?
The warm-up ischemia phenomenon requires initial myocardial ischemia of more than moderate intensity, whereas exercise under the ischemic threshold only increases short-term exercise capacity.
Absolute Event Rate: 23.5% vs 20.3%
p-value: p=<0.0001
BACKGROUND: The relation of the warm-up ischemia phenomenon to the presence and intensity of initial myocardial ischemia is unclear. We sought to determine whether the warm-up ischemia phenomenon requires initial myocardial ischemia or can be induced by exercise without ischemia and whether there is a relation between the intensity of initial ischemia and the attenuation of ischemia on reexercise. METHODS AND RESULTS: Twelve subjects with exertional myocardial ischemia performed 2 exercise ECG tests (1 and 2) at a +/-10-minute interval on 3 occasions (A, B, C) 1 month apart. A1 and A2 were symptom-limited. B1 was kept as long as A1, but its intensity was held under the ischemic threshold (heart ratexsystolic pressure at 1-mm ST depression STD) noted at A1. B2 was symptom-limited. C1 was also kept as long as A1 but with an intensity adjusted to maintain one-half maximum STD of A1. C2 was symptom-limited. Exercise duration of A2, B2, and C2 increased similarly compared with A1 (P=0.009). However, the ischemic threshold (x10-3) increased at A2 (23.5+/-6.0) compared with A1 (20.3+/-4.8; P<0.0001) but not at B2 (19.8+/-5.0) or C2 (21.5+/-5.8). Similarly, maximum STD adjusted to the highest heart rate-systolic pressure product common to A1, A2, B2, and C2 decreased at A2 (1.4+/-0.7 mm) compared with A1 (2.5+/-0.9 mm; P<0.0001) but not at B2 (2.7+/-0.9 mm) or C2 (2.3+/-0.9 mm). CONCLUSIONS: Exercises under the ischemic threshold and of intermediate ischemic intensity increase short-term exercise capacity, but myocardial ischemia of more than moderate intensity is needed to induce the warm-up ischemia phenomenon.
Bogaty et al. (Mon,) conducted a other in Exertional myocardial ischemia (n=12). Exercise tests with varying intensities of initial ischemia vs. Baseline symptom-limited exercise was evaluated on Ischemic threshold (heart rate x systolic pressure at 1-mm ST depression) (p=<0.0001). Symptom-limited initial exercise induced the warm-up ischemia phenomenon by increasing the ischemic threshold on re-exercise (23.5 vs 20.3; P<0.0001), whereas lower intensity exercise did not.
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