Safety and observer variability of cardiac magnetic resonance imaging combined with low-dose dobutamine stress-testing in patients with complex congenital heart disease

Abstract

In patients with complex congenital heart disease (CHD) abnormal ventricular stress responses have been reported with dobutamine stress cardiovascular magnetic resonance (DCMR). These abnormal stress responses are potential indicators of long-term outcome. However, safety and reproducibility of this technique has not been reported in a larger study. The aim of this study was to report our experiences regarding safety and intra-observer and inter-observer variability of low-dose DCMR in complex CHD. In 91 patients, 110 low-dose DCMR studies were performed with acquisition of a short axis set at rest, and during dobutamine administration (7.5 μg/kg/min maximum). We assessed biventricular end-diastolic volumes, end-systolic volumes, stroke volumes, ejection fraction and ventricular mass. Intra- and inter-observer variability for all variables was assessed by calculating the coefficient of variation (%), i.e. the standard deviation of the difference divided by the mean of 2 measurements multiplied by 100%. In 3 patients minor side effects occurred (vertigo, headache, and bigeminy). Ten patients experienced an increase in heart rate of >150% from baseline, although well tolerated. For all variables, intra-observer variability was <10% at rest and during stress. At rest, inter-observer variability was 10.5% maximal. With stress-testing, only the variability of biventricular end-systolic volumes (ESV) exceeded 10%. In patients with complex CHD low-dose DCMR is feasible, and safe. Intra-observer variability is low for rest and stress measurements. Inter-observer variability of biventricular ESV is high with stress-testing. Whether this limits the potential usefulness of DCMR for risk assessment during follow-up has to be assessed.