Key result
Combined treadmill exercise duration and peak RPP criteria differentiate syndrome X from CAD with ~86% specificity.
Why the study?
It is difficult to differentiate syndrome X from coronary artery disease by treadmill exercise test in elderly patients with chest pain and exercise-induced myocardial ischemia.
Can treadmill exercise test parameters differentiate syndrome X from coronary artery disease in elderly patients with chest pain and exercise-induced myocardial ischemia?
Case-Control (n=110)
Can treadmill exercise test parameters differentiate syndrome X from coronary artery disease in elderly patients with chest pain and exercise-induced myocardial ischemia?
A simple combined criterion of exercise duration and rate-pressure product during a treadmill test can help differentiate syndrome X from coronary artery disease in elderly patients with chest pain.
Treadmill testing cannot reliably differentiate syndrome X from CAD in elderly patients; leaves open need for better noninvasive diagnostics.
Even though the underlying mechanisms of myocardial ischemia may be different, it is difficult to differentiate syndrome X from coronary artery disease (CAD) by means of the treadmill exercise test in elderly patients with chest pain and exercise-induced myocardial ischemia. One hundred sex- and age-matched patients-42 with syndrome X and 58 with CAD-were studied. Another 10 subjects with atypical chest pain, negative treadmill exercise test, and normal-appearing coronary angiograms served as controls. We evaluated the difference in exercise performance between patients with syndrome X and CAD, and the treadmill exercise test was undertaken with modified Bruce protocol within 2 weeks before coronary angiography. Parameters including time to 1 mm ST segment depression (STD), exercise duration (ED), heart rate (HR), systolic blood pressure, rate-pressure product (RPP), and percentage of age-predicted maximum HR (% HR) at different stages of the test were measured and then compared among the three groups of patients. Compared with CAD patients, syndrome X patients had significantly higher HR, % HR, and RPP at the time of 1 mm STD and at peak exercise. The time to 1 mm STD and ED were longer in syndrome X than in CAD patients. However, ED was shorter and HR, % HR, and RPP at peak exercise were similar in syndrome X patients as compared with control subjects. The new criterion of combined ED (> or =315 seconds) and RPP at peak exercise (> or =24,000 beats x mmHg/min) was found to be highly specific (86%) and moderately sensitive (64%) in differentiating syndrome X from CAD patients. The positive likelihood ratio for this criterion was 4.57 and negative likelihood ratio was 0.42. In conclusion, syndrome X patients had better exercise performance than CAD patients, but less ED and similar workload when compared with control subjects. The new criterion proposed in this study may provide a quick and simple way to differentiate syndrome X from CAD in a group of aged and predominantly male patients with chest pain and positive treadmill exercise test.
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Hsu et al. (1998) conducted a case-control in Chest pain and exercise-induced myocardial ischemia (n=110). Syndrome X vs. Coronary artery disease (CAD) and normal controls was evaluated on Differentiation of syndrome X from CAD using combined exercise duration (≥315 seconds) and rate-pressure product at peak exercise (≥24,000 beats x mmHg/min) (Sensitivity 64%, Specificity 86%, LR+ 4.57, LR- 0.42). A treadmill exercise test criterion of exercise duration ≥315 seconds and peak rate-pressure product ≥24,000 differentiated syndrome X from CAD with 86% specificity and 64% sensitivity.
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