Implications of exercise test modality on modern prognostic markers in patients with known or suspected coronary artery disease: Treadmill versus bicycle

BACKGROUND: Important modern prognostic markers such as heart rate recovery (HRR), chronotropic index, delayed systolic blood pressure (SBP) response and Duke treadmill score (DTS) have been evaluated by treadmill exercise testing. Their value in bicycle exercise testing is unclear. METHODS: Patients (n=211, age 64+/-10; 75% male) with known or suspected coronary artery disease randomly underwent either bicycle (n=105) or treadmill (n=106) exercise electrocardiography. They were matched for age, gender, body mass index, hypertension, smoking, lipid status, prevalence of diabetes, medication, haemoglobin level, extent of coronary artery disease and left ventricular ejection fraction. RESULTS: Despite a higher peak heart rate (pHR) patients stressed by treadmill had a slower drop in HR during the early phase of recovery with a significantly higher rate of abnormal HRR (pHR; HR 1 min into recovery < or =12 bpm) with 37% in treadmill versus 19% in bicycle (P=0.004). Abnormally delayed SBP response [(SBP 1 min into recovery/SBP 3 min into recovery) >1.0] was also more common in treadmill (41%) compared to bicycle (12%, P<0.001). However, the rate of chronotropic incompetence [(pHR - rest HR)/(220 - age - rest HR) <0.8] was significantly lower in treadmill than in bicycle (60 versus 76%, P<0.001). Mean DTS was also significantly higher in treadmill compared to bicycle (4.8+/-6.5 versus 3.6+/-5.1, P=0.03) mainly due to the higher workload achieved when patients were stressed by treadmill (8.5+/-2.5 versus 6.1+/-1.5 metabolic equivalents, P<0.001). CONCLUSIONS: Further adjustment is needed prior to routine incorporation of these important measures into interpretation of bicycle exercise testing.