The clinical impact of dynamic intraventricular obstruction during dobutamine stress echocardiography

We selected 73 consecutive patients without myocardial-infarction, hypertrophic cardiomyopathy or hypertension complaining of effort chest discomfort/dyspnoea, and/or reporting exercise ischaemic ECG changes, and submitted them to simultaneous dobutamine stress echocardiography (DSE) and 99mTc tetrofosmin SPECT (T SPECT) and to coronary angiography to evaluate the clinical impact of intraventricular obstruction (IVO) during dobutamine infusion. Sixteen patients (22%, 7 males, mean age+/-SD 63+/-8 years, group 1) developed IVO (mean CW Doppler velocity+/-SD: 3.8+/-1.0 m/s) and 57 (41 males, mean age+/-SD 63+/-10 years, group 2) did not. The two groups had similar incidence of angina and ischaemic ECG changes at exercise tolerance test. DSE did not demonstrate wall motion abnormalities in any group 1 patient while T SPECT showed a perfusion defect in the only one with coronary artery disease (CAD). DSE reproduced symptoms in a higher percentage of patients with than without IVO, while there was no statistical difference in the reproduction of ischaemic ECG changes, despite CAD prevalence was much lower in group 1. Group 1 patients remained asymptomatic on beta-blockers at 12-month follow-up. Dobutamine-induced IVO, by reproducing symptoms, suggests that IVO plays a role in the clinical setting in patients without CAD complaining of unexplained reduced effort tolerance who should undergo DSE.