The quantitative contribution of AV-plane motion to LV pumping in controls, athletes and patients with dilated cardiomyopathy measured by MR imaging Carlsson M, Hard L, Eliasson M, Mosén H, Ugander M, Buhre T, Arheden H. INTRODUCTION: Previous studies using echocardiography in healthy subjects have reported conflicting data regarding the percentage of the stroke volume resulting from atrioventricular plane motion (AVPM). AIM: To quantify the percentage of SV explained by AVPM in controls, athletes and patients with decreased left ventricular function due to dilated cardiomyopathy (DCM) using cardiac magnetic resonance (CMR) imaging. METHODS: 12 healthy subjects (mean age 24 years, 5 women), 12 elite triathletes (mean age 35 years, 4 women) and 12 patients with DCM and ejection fraction below 30 % (mean age 54 years, 4 women) were examined by cine CMR. Maximum AVPM between end-diastole and end-systole was measured at two points in each of three long axis planes and expressed as the average of the six points. The SV was calculated from contiguous short axis images by established techniques. The mean epicardial area of the largest short axis slices in end-diastole was multiplied by the AVPM and divided by the SV to calculate the percentage of SV explained by longitudinal function (AVPM/SV). Data is presented as mean±SEM. RESULTS: SV for controls was 116±6 ml. SV was increased in athletes 140±4 ml (p=0.01) and decreased in patients 72±7 ml (p<0.001). AVPM for controls was 16±0 mm. AVPM was unchanged for athletes 17±1 mm (p=ns) and decreased for patients 7±1 mm (p<0.001). AVPM/SV for controls was 60±2 %. AVPM/SV was unchanged for athletes 57±2 % (p=ns) and for patients 67±4 % (p=ns). CONCLUSIONS: AV-plane motion is the primary contributor to LV pumping accounting for about 60 % of the stroke volume. Although AVPM is less than half in patients with DCM compared to controls and athletes, the contribution of AVPM to LV function is maintained which can be explained by the larger short-axis area in the dilated left ventricle.