John Coffey, Presenter: Nothing to Disclose

Jon Hill, Abstract Co-Author: Nothing to Disclose

Obesity influences cardiovascular morbidity and mortality and is associated with left ventricular dysfunction. Echocardiography and autopsy examinations have shown associations between mild to moderate obesity and alterations of cardiac structure and of systolic function. Volumetric data acquired by gated SPECT perfusion imaging has advantages over echocardiography in being automated and relatively independent of technical difficulties produced by obese body habitus. The objective of this study was to compare cardiac index,CI,(cardiac output,CO,corrected for body surface area),stroke volume index,SVI,left ventricular ejection fraction,LVEF,and regional myocardial wall thickening,of obese and normal weight patients using gated SPECT MIBI perfusion imaging. This was in order to assess haemodynamic function, represented by CI and systolic function represented by LVEF,SVI regional myocardial wall thickening.

32 obese patients(body mass index,BMI>30,mean 35)with 50 patients with BMI<30,(mean 26),referred for evaluation of chest pain,dyspnoea or inconclusive exercise ECG,were studied in an outpatient setting following injection of 400MBq Tc99mMIBI.Gated SPECT imaging was performed after treadmill Bruce protocol. CO was calculated as the product of SV and resting heart rate and CI determined. Systolic myocardial wall thickening was determined for the anterior , lateral and infero-septal walls of the left ventricle.

Mean CI was 2.28l/sqm/min for obese and 2.24l/sqm/min for normal weight patients. T tests showed no significant difference in mean CI or in stroke volume between the two groups. LVEF (mean 62.5%)was increased (p<0.03) but SVI was reduced,(p<0.02) for the obese group. Systolic myocardial wall thickening was increased,(p<0.03),in the lateral and infero-septal regions in the obese group.

Haemodynamic function, as CI, was equivalent for obese and normal weight patients. Hypersystolic function, manifest as relatively increased LVEF and regional myocardial wall thickening, was noted in the obese group.

Hyperdynamic or elevated systolic function, is required by obese subjects to maintain an equivalent CI and haemodynamic status to normal weight patients.

Coffey, J, Hill, J, Myocardial Contractility and Cardiac Index in Obese and Normal Weight Patients Using SPECT MIBI Perfusion Imaging.  Radiological Society of North America 2006 Scientific Assembly and Annual Meeting, November 26 - December 1, 2006 ,Chicago IL. http://archive.rsna.org/2006/4427147.html