Different exercise performance between aged patients with syndrome X and those with coronary artery disease

Both patients with coronary artery disease (CAD) and those with syndrome X (anginal chest pain, exercise-induced myocardial ischemia, normal coronary angiogram and no evidence of coronary spasm) have ischemic electrocardiogram (ECG) during exercise. However, the difference of ECG change during treadmill exercise test in these two patient groups has rarely been studied.

In this prospective study, we evaluated and compared the changes of hemodynamics and 12-lead ECG during treadmill exercise test by modified Bruce protocol in 29 patients with syndrome X and 46 patients with CAD.

As compared with CAD patients, syndrome X patients had significantly higher heart rate, higher systolic blood pressure and higher rate-pressure product at 1mm ST depression and peak exercise. The time to 1mm ST depression (304 +/- 128 vs 254 +/- 92 seconds, p = 0.06) and total exercise duration (463 +/- 108 vs 331 +/- 111 seconds, p < 0.001) were also longer in syndrome X than in CAD patients. However, coronary flow reserves, obtained from 20 syndrome X patients and 9 CAD patients, did not differ between both groups. (2.3 +/- 0.6 vs 2.5 +/- 0.6, p = NS) CONCLUSIONS: Patients with syndrome X had higher ischemic threshold and better exercise tolerance than CAD patients though coronary flow reserve was similar between them. During exercise, more work-load as well as metabolic demands was required for the development of similar degree of myocardial ischemia in these aged syndrome X patients as compared with CAD patients.