The value of ^99mTc-MIBI myocardial perfusion imaging in differentiation of heart failure conditioned by global left ventricular systolic impairment

Objective. The global left ventricular systolic impairment with left ventricular dilatation can manifest due to idiopathic dilated cardiomyopathy or ischemic heart disease and can present a similar clinical picture of severe heart failure. The aim of our investigation was to assess a differential diagnostic value of resting 99mTc-MIBI myocardial perfusion defects in evaluation of the etiology of heart failure.
Material and methods. The data of 2D echocardiography, coronary angiography, and myocardial gated single photon emission computed tomography with 99mTc-MIBI investigation were evaluated in 43 patients with global left ventricular systolic impairment, characterized by left ventricular end-diastolic diameter of ≥65 mm and ejection fraction of £40%. The idiopathic dilative cardiomyopathy was diagnosed in 26 patients (Group 1) and ischemic heart failure – in 17 patients (Group 2). The area and the degree (severity) of myocardial perfusion defects (AMPD and DMPD) at rest in regions supplied by three coronary arteries were evaluated in all the patients.
Results. The area of perfusion defects in the left anterior descending (LAD) and right coronary artery (RCA) regions in dilative cardiomyopathy patients was smaller than in ischemic heart failure patients (1.43±0.9 vs 2.53±0.53, P=0.001, and 2.19±0.6 vs 2.82±0.56, P=0.02). The degree of perfusion defects was also less severe in the same circulation regions (1.39±0.93 vs 2.59±0.6, P=0.01, and 1.6±0.46 vs 2.71±0.15, P=0.001). We have designed a logistic regression model expressed by formula x=2.52AMPDrca+2.47AMPDlad+2.21DMPDrca. Idiopathic dilative cardiomyopathy was predicted when x was £16 and ischemic heart failure when x was >16. The sensitivity in predicting idiopathic dilative cardiomyopathy was 94.44%, and the specificity was 88.24%.
Conclusion. The difference in the area and degree of ^99mTc-MIBI myocardial perfusion defects at rest in patients with heart failure caused by idiopathic dilative cardiomyopathy or ischemic heart failure is measurable and has a predictive value for differentiation of the etiology of global left ventricular systolic impairment.