Key result
Diastolic perfusion time shows significantly lower variability at ischemic threshold than heart rate across stress tests.
Why the study?
The relevance of diastolic perfusion time in the mechanisms underlying stress-induced ischemia was evaluated due to limited understanding of its role.
RCT (n=23)
randomized
p-value: p=<0.0001
Diastolic perfusion time may influence ischemia mechanisms; leaves open its clinical relevance pending larger studies.
BACKGROUND: To evaluate the relevance of diastolic perfusion time on the mechanisms underlying stress-induced ischemia, 16 patients with coronary artery disease and seven patients with syndrome X underwent five randomized stress tests (upright and supine exercise with and without therapy, transesophageal atrial pacing). METHODS AND RESULTS: Exercise duration Time to 0.1 mV ST segment depression, heart rate, rate-pressure product, and diastolic perfusion time were evaluated for each patient during stress tests. In both groups, variability coefficients of the above-mentioned parameters were not different at rest. At ischemic threshold (0.1 mV ST segment depression) in patients with coronary artery disease, the variability coefficient of exercise duration (40.1 +/- 22.2) was significantly higher (p less than 0.0001) than those of heart rate (12.8 +/- 2.9), rate-pressure product (14.8 +/- 3.3), and diastolic perfusion time (0.39 +/- 0.1). The variability coefficient of diastolic perfusion time was also significantly (p less than 0.0001) lower than those of heart rate and rate-pressure product. Similarly, the variability coefficient of diastolic perfusion time (0.44 +/- 0.1) in syndrome X patients was significantly lower (p less than 0.0001) than those of exercise duration (28.2 +/- 9.4), heart rate (12 +/- 1.4), and rate-pressure product (14.6 +/- 1.3). CONCLUSIONS: Fixed diastolic perfusion time at ischemic threshold, despite different kinds of stress tests and variability of heart rate and rate-pressure product, indicates the relevant role of diastolic perfusion time in determining myocardial ischemia.
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Ferro et al. (1991) conducted an RCT in Coronary artery disease and syndrome X (n=23). Five randomized stress tests (upright and supine exercise with and without therapy, transesophageal atrial pacing) was evaluated on Variability coefficient of diastolic perfusion time at ischemic threshold (p=<0.0001). Across five randomized stress tests, the variability coefficient of diastolic perfusion time at ischemic threshold was significantly lower than that of heart rate and rate-pressure product (p<0.0001).
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