Role of hybrid single photon emission computed tomography myocardial perfusion imaging/ computed tomography coronary angiography in detecting coronary artery disease in patients with dilated left ventricle and reduced ejection fraction

DMCP is a diagnosis of exclusion, it is essential to rule out ischemic causes in these patients presenting with LV dysfunction. Though ICA is the investigation of choice, the complications associated with it are quite high in these patients with reduced ejection fraction. Hence, we have fused non-invasive diagnostic modalities like SPECT MPI and CTCA to assess the functional and anatomical status of the myocardium and coronaries, respectively. The study aim was to to detect the proportion of CAD in patients with dilated left ventricle (LV) and reduced EF based on image patterns on hybrid (SPECT MPI /CTCA) imaging. 30 patients with dilated LV defined as LV end-systolic diameter >40 mm or LV end-diastolic diameter >55 mm on echocardiography and reduced LVEF defined as <40% on echocardiography were recruited for the study from July 2020 to June 2022. All patients underwent stress SPECT MPI and CTCA within a period of one week. The three-dimensional LV myocardium and coronary tree were fused using Cardiac IQ fusion software. The proportion of patients with matched or unmatched perfusion and structural defects was evaluated. Results: Out of 30 patients, 7 (23%) patients had abnormal MPI findings, with most of them having severe perfusion defects (n = 4) involving a larger extent (n = 7) of the left ventricular myocardium. Nineteen patients (63%) had normal coronaries. Of the abnormal CTCA results, the most common coronary artery found to be stenotic was LAD (n = 7, 23%). Stenosis of more than 50% of the coronary lumen was found in 5 patients (17%). Of the 7 patients with abnormal findings on hybrid imaging, 5 (17%) patients had matched defects in SPECT MPI and CTCA, with most of the defects corresponding to the LAD territory (n = 4). Two (6%) patients had perfusion defects but normal coronaries (unmatched findings). Overall, 23% (95% confidence interval: 8 to 38%) of patients had coronary artery disease as defined by matched and unmatched perfusion defects in hybrid imaging. Hybrid SPECT MPI/CTCA imaging is feasible in patients with dilated LV cavity and reduced EF. Integrated SPECT MPI and CTCA imaging helped visualize both coronary lesions and perfusion defects and therefore enhanced confidence in reporting CAD. (author)