Transient cavity dilatation during supine exercise bicycle stress testing: mechanistic insights

BACKGROUND: Cavity dilatation is occasionally observed during supine bicycle exercise stress echocardiography (SBSE). The underlying mechanisms are poorly understood. AIMS: This study aimed to characterise patients with left ventricle (LV) cavity dilatation and a decrease in the left ventricular ejection fraction (LVEF) during SBSE. METHODS: A total of 653 patients who underwent SBSE were evaluated. Those with exercise-induced cavity dilatation (defined as increased cavity size and a decrease in LVEF) were evaluated (n = 29). A control group (n = 37) of patients with a hypertensive response and a normal ESE was also evaluated. RESULTS: A total of 33/653 (5.1%) patients had an abnormal LV cavity response to exercise, with 15/29 (51.7%) having significant underlying coronary artery disease (CAD). Comparisons were made between patients with CAD (n = 15) and those with nonobstructive coronary arteries (NCAs, n = 14). NCA patients had significantly higher peak diastolic blood pressure (DBP) (NCA-CD 109 ± 17 mmHg vs. CAD-CD 96 ± 16 mmHg, p = 0.044) and rate-pressure product (RPP) (NCA-CD 28,623 ± 4474 vs. CAD-CD 23,649 ± 4763, p = 0.007). There was a trend toward increased dyspnoea at peak exercise in NCA (NCA-CD 35.7% vs. CAD-CD 6.7%, p = 0.080), and CAD patients showed a higher observed frequency of severe chest pain (CAD 53.3% vs. NCA 14.3%, p = 0.050). When patients with NCA and cavity dilatation were compared with a control group of patients with a hypertensive response to exercise but no cavity dilatation, no significant differences were observed. CONCLUSION: Cavity dilatation is observed in 5% patients undergoing SBSE and is attributable to significant CAD in approximately half of patients. NCA cavity dilatation is associated with increased RPP and DBP at peak exercise, with a trend toward increased dyspnoea. Severe chest pain at peak exercise was observed more frequently in CAD patients.