Gated single photon emission tomography MIBI stress perfusion imaging for assessing cardiac output and index in obese and non-obese patients.

OBJECTIVE: To compare cardiac index, (CI) [i.e. Cardiac output (CO) corrected for body surface area], stroke volume index (SVI) and left ventricular ejection fraction (LVEF) of obese and non obese patients using gated Gated Single Photon Emission Computed Tomography (SPECT) MIBI perfusion imaging. This was done in order to assess haemodynamic function, represented by CI and systolic function represented by LVEF and SVI.
MATERIALS AND METHODS: Forty-one obese patients (BMI >30, mean 35.3) with 65 patients with BMI <30, (mean 25.8), 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 product of SV and resting heart rate and CI determined.
RESULTS: Mean CI was 2.26 l/min/m(2) for obese and 2.18 l/min/m(2) for non obese patients. T tests showed no significant difference in mean CI or in SV between the two groups although CO was significantly increased for the obese group. LVEF was elevated in the obese group, mean LVEF 62.5% compared with mean LVEF of 58% in the non obese group (P < 0.05). SVI was reduced for the obese group (P < 0.03).
CONCLUSIONS: Haemodynamic function, as CI, was similar for obese and non-obese patients. Hypersystolic function, manifest as relatively increased LVEF, was noted in the obese group.