Comparison Of Peak Image Acquisition Characteristics Between Supine Bicycle And Treadmill Exercise Echocardiography

Exercise echocardiography (EE) using supine bicycle (SB) or treadmill (TM) is widely used to diagnose coronary artery disease (CAD). Among the two exercise modalities, it is believed that peak exercise workload achieved with EE using SB is less when compared to EE using TM due to a lower peak exercise heart rate. Despite this, the limited studies comparing the two modalities directly have shown that EE with SB has better sensitivity and comparable specificity to EE with TM. The delay in peak exercise imaging acquisition (occasionally >30 seconds) with EE with TM, done at a time when the patient is no longer exercising and cardiac workload is decreasing, may be an explanation of this. PURPOSE: In this study, we aim to compare the exercise workload characteristics at peak image acquisition (IA) between EE with SB and EE with TM in evaluating CAD. Method: We retrospectively assessed peak exercise and peak IA exercise workload of 173 consecutive patients who underwent EE either with SB or TM to evaluate CAD in our institute from January 2007 to August 2008. Of these exercise echocardiograms, 21 were with SB(age 49 ±9) and 152 were with TM (age 49 ±14). Result: At peak exercise patients who underwent EE with TM had higher HR as compared to EE with SB, but comparable rate pressure product, an index of oxygen consumption (RPP; HR x systolic BP). The mean delay in image acquisition of EE with TM was 11± 4 seconds (no delay in SB). However, at peak IA, both HR and RPP were comparable between the two tests. (percentage of predicted HR to maximum predicted HR; 83±9 vs 88±8%, P= 0.13, RPP; 2,56±4.70 vs 2.47± 5.37 103·bpm·mmHg, P=0.55). CONCLUSION: Our results show that at peak IA there was no difference in HR and there was a trend towards higher systolic BP in EE with SB as compared to EE with TM. This suggests that workload characteristics of EE with SB at actual IA is not inferior to EE with TM for evaluating CAD.