Prognostic value of myocardial scar burden using cardiac magnetic resonance in ischemic and non-ischemic cardiomyopathy

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Myocardium is a unique muscle type designed to perform a specific function; conducting electrical activity to both ventricle simultaneously to contract and relax in a synchronized manner. Therefore, evaluation of the myocardial muscle function only using left ventricular ejection fraction (LVEF) would be inaccurate. However, assessment of the myocardium on the tissue level, is expected to provide more precise data regarding the ability to conduct, contract and relax properly. Purpose is to evaluate the prognostic value of myocardial scar using CMR on the clinical outcome in patients with ischemic cardiomyopathy (ICM) and non-ischemic cardiomyopathy (NICM). Methods 154 patients with either ICM or NICM underwent CMR (using 1.5T) for assessment of LVEF, detection and quantification of any myocardial scar by calculating the percentage (%) of scar mass to the whole myocardial mass (using manual quantification of scarred tissue in each myocardial segment, summed and divided by the total myocardial mass). Patients were followed up for at least 6 months for any cardiac events. These events were scaled according to severity from 1 (asymptomatic) to 7 (most severe), including; no symptoms, mild non-acute chest pain, mild dyspnoea (NYHA I-II), hospital admission due to decompensated heart failure, syncope, documented ventricular arrhythmia and sudden cardiac arrest/death, respectively. Statistical correlation between the amount of scarred myocardium in both ICM (group I) and NICM (group II) patients and the severity of the clinical events during the period of the follow up was performed. The study included 154 patients, 56% were males, mean age of 61 years with minimal follow up duration of 6 months. Patients were divided into: group I with ICM (58%) and group II with NICM (42%). Clinical presentation was ranging from eventless (10%), chest pain (18%), heart failure (15%), hospitalization (35%), syncope (1%), ventricular tachycardia (<1%) and up to cardiac arrest (<1%). Direct relationship was observed between scar size and event severity in the two groups (P value < 0.001). However, inverted relationship between LVEF and event severity in group I (P value of < 0.001) was detected but not in group II (P value 0.128), as shown in figure 1. Low EF was mainly linked with hospitalization in both ICM and NICM. It was observed that serious cardiac events were less detected in patient with mean scar mass < 5.4–8.4% . However, patients who have experienced sudden cardiac arrest have a mean scar mass of 15.9 % and patients with ventricular tachycardia with mean of 9.8%. Conclusion The amount of scarred myocardium is found to be directly linked to the severity of the clinical event in both ICM and NICM. Therefore, quantification of myocardial scar could be used as a predictor for cardiac events, hospitalization and sudden cardiac death.