A comparative study of invasive (coronary angiography) and non-invasive (MUGA and myocardial gated SPECT) methods of cardiac ejection fraction measurements.

Abstract

Background Cardiovascular disease (CVD) is the leading cause of death in the industrialised world, including Malta. In the assessment of CVD, the accurate estimation of left ventricular ejection fraction (L VEF) is vital for appropriate patient management. Without proper L VEF computation, patients deserving implantable cardiac devices might be denied this crucial therapy. At present, patients admitted to the local general hospital may undergo multiple examinations for the same medical problem, which might be deemed unnecessary. Aims This study was conducted with the intention of determining: ( 1) whether a correlation exists among LVEF values calculated by the invasive modality (angiography) and the non-invasive modalities (multiple gated acquisition (MUGA) and myocardial gated single-photon emission tomography (SPECT)); (2) whether a correlation exists among MUGA and SPECT (both non-invasive modalities); and (3) how the LVEF calculated by the three modalities differs. Finally, results were aimed to be compared with other studies. Methodology A quantitative, non-experimental, retrospective study was conducted, whereby L VEFs of patients of any age and gender who underwent 2': 2 examinations (angiography and/or MUGA and/or SPECT) between January 2008 and March 2010 at the local general hospital were gathered. The sample contained 111 patients: 11 underwent all three examinations, 10 had MUGA and SPECT, 45 had MUGA and angiography, and 45 had SPECT and angiography. Results The mean LVEFs are as follows; angiography: 52.63 (range= 9.50- 95.80; a= 21.11); MUGA: 37.71 (range= 7.00 -76.00; a= 15.28); SPECT: 52.85 (range= 14.00 - 79.00; a = 15.61). A good to excellent correlation was found between MUGA and SPECT (r = 0.79; p < 0.0001), while moderate to good correlations were attained for SPECT-angiography (r = 0.71; p < 0.0001) and MUGA-angiography (r = 0.65; p < 0.0001). SPECT-angiography have a fairly significant difference (t = 5.16; p < 0.0001; mean difference= 8.73), while SPECT-MUGA (t = 0.59; p = 0.56; mean difference= 1.38) and MUGA-angiography (t = 0.95; p = 0.35; mean difference = 1.63) have a minute insignificant difference among them. Results show that MUGA and SPECT as a pair accurately determine a normal or diminished L VEF. This cannot be said for the other modality pairs, with SPECT -angiography illustrating an overestimation by angiography or an underestimation by SPECT. Results for MUGA-angiography are inconclusive. Conclusions Results show that the non-invasive modalities correlate best with one another than with invasive angiography. They also have the smallest difference among their values. Angiography correlates best with SPECT, yet there is a significant difference between their L VEFs. Angiography and MUGA have the lowest correlation, but with a minute insignificant difference among them. Utilising MUGA and SPECT would provide more comparable results with the added benefits of risk reduction and having patients undergo fewer examinations, thus affecting a reduction in hospital costs.