Correlation between Cardiac Magnetic Resonance Derived Myocardial Salvage Index & Different Variables in Patients with Acute Anterior ST Elevation Myocardial Infarction Treated with Primary Percutaneous Coronary Intervention & Its Prognostic Implications

Abstract

SUMMARY C MR is a currently available tool that can quantify the success of revascularization reflected by the amount of salvaged myocardium with a strong predictive value of subsequent clinical outcome. So far, infarct size, MSI and MO were the most used CMR end points associated with global and regional functional recovery as well as MACEs. Thirty Patients presented to our facility with acute anterior STEMI, reperfused by Primary PCI within 12 hours from symptoms onset, then assessment of CMR-derived MSI was performed on day 2 - 4 after primary PCI using 1.5 Tesla machine. MVO and infarction size volumes were evaluated in late gadolinium enhancement (LGE) CMR. Different demographic data and clinical risk factors of different patient groups were obtained. Peri-procedural aspects and time intervals of PPCI and following echocardiography were recorded for different patients. Patients were followed up clinically for Major Adverse Cardiac Events (MACE) during hospital stay and up to 6 months. The mean age was 49.37 ± 9.98 years (83.3% males). Patients were categorized into 2 groups as regard MSI (15 patients had MSI above the median value, and 15 patients had MSI below this value), and another 2 groups as regard MVO (14 patients had MVO, and 16 patients had no MVO). There was no significant difference among the patients as regard the demographic data and risk factors. Patients with lower MSI and patients with MVO had more incidence of major adverse cardiovascular events within the first 6 months post PPCI (p=0.003, p=0.001 respectively). Patients with lower MSI and patients with MVO had higher Killip class on presentation to ER (P=0.03, P=0.018 respectively). Shorter peri-procedural time intervals, total ischemic time, and time from onset of pain to resolution of ST segment deviation were clearly found in patients with higher MSI and also in patients with no or minimal MVO. Also those patients had lower enzymatic elevation of CK (total and MB fraction), smaller infarction size, better LV systolic function, and smaller LV end- systolic and end-diastolic dimensions. Also there was significant correlation between the presence of MVO in CMR study and post-procedural (MBG and thrombus grade), (p=0.021, p=0.022 respectively). However, the angiographic MBG is still a subjective projection of microcirculation, it may differ from one person to the other even between well trained operators. But the CMR is more objective projection of the microcirculation, with little or no inter-observer difference having more accurate assessment of the microcirculation.