P1395 New predictors of burned-out phase in hypertrophic cardiomyopathy

Abstract

BACKGROUND Hypertrophic cardiomyopathy (HCM) is a heart disease characterized by hypertrophy of the left ventricular myocardium. The structural and functional abnormalities cannot be explained by flow-limiting coronary artery disease or loading conditions. HCM has a benign course, however approximately 5% of these patients suffer from the end-stage of the disease. The so-called burned-out phase, characterized by systolic dysfunction with a left ventricular ejection fraction ≤50%, is often associated with wall thinning and chamber dilation. These patients should have more frequent clinic visits and have a more intensive treatment plan. They are also candidates for heart transplantation. Currently there are no risk factors of progression to burned-out phase before the onset of heart failure symptoms. Therefore, the potential risk factors: left ventricular global longitudinal strain (GLS), left ventricular average strain (ASI), right ventricular average strain (RV-ASI) and left atrial volume index (LAVI), have been examined. GLS, derived from speckle tracking echocardiography, and ASI, derived from tissue doppler imaging, are the sensitive and noninvasive methods of assessing the ventricular function. LAVI more accurately characterizes the size of the left atrium, which usually increases in the course of the disease. METHODS A total of 252 patients with HCM (aged 20-88 years, 49,6% were men), treated in our Department have been enrolled in the study. GLS, ASI, RV-ASI and LAVI assessment has been made in addition to standard echocardiographic examination. Burned-out was characterized as systolic dysfunction with a left ventricular ejection fraction ≤50%. RESULTS 5.6% patients in the study population were diagnosed with burned-out phase in hypertrophic cardiomyopathy. The t-Student test and t-Student test with Cochran-Cox adjustment showed statistically significant differences of GLS and ASI values between burned-out and non-burned-out groups; p = 0.000001 and p < 0.000001, respectively. Average and median values of GLS in burned-out group were -7.4% ± 2.9%, -7.1% and -15.3% ± 4.3%, -15.4% in non-burned-out group. For ASI those values were respectively -7.6% ± 2.2%, -7.1% and -12.9% ± 4.5%, -13.0%. The Mann-Whitney test showed statistically significant differences of RV-ASI and LAVI values between burned-out and non-burned-out groups; p = 0.000208 and p = 0.005302, respectively. Median value of RV-ASI in burned-out group was -15.8% and -27.1% in non- burned-out group. Median value of LAVI in burned-out group was 52.6 ml/m2 and 37.8 ml/m2 in non-burned-out group. CONCLUSIONS Each of the proposed new risk factors of burned-out development was statistically significant in the study population. Therefore, all HCM patients should have regular echocardiographic examinations and those with deteriorating values of new parameters should become the subjects of intensified medical care.