Clinical features, etiology and survival in patients with restrictive cardiomyopathy: A single center experience

Background: Numerous prognostic factors have been proposed for cardiac amyloidosis (CA). The knowledge about other subtypes of restrictive cardiomyopathy (RCM) is scant. Aims: To reveal the etiology, identify prognostic factors, and assess cardiac biomarkers, high-sensitive troponin T (hs-TnT), growth differentiation factor-15 (GDF15), N-terminal-proB-type natriuretic peptide (NT-proBNP) and soluble suppression of tumorigenicity 2 (sST2), as death predictors in RCM. Methods: 36 patients with RCM in the referral cardiology department were enrolled. All patients were screened for CA. Genetic testing was performed in 17 patients without CA. Results: Pathogenic or likely pathogenic gene variants were found in 86% of patients, including 5 novel variants. Twenty patients died and 4 had a heart transplantation during the study. Median overall survival was 29 months (8­–55). The univariate Cox models analysis indicated that systolic and diastolic blood pressure, GDF15, hs-TnT, NT-proBNP, left ventricular stroke volume, the ratio of the transmitral early peak velocity (E) estimated by pulsed wave Doppler over the early mitral annulus velocity (e’), tricuspid annulus plane systolic excursion, early tricuspid valve annular systolic velocity, the presence of pulmonary hypertension, and pericardial effusion influenced survival ( P <0.05). A worse prognosis was observed in patients with GDF15 >1316 pg/ml, hs-TnT >42 ng/l, NT-proBNP >3383 pg/ml and pericardial effusion>3.5 mm (the Kaplan-Meier analysis, Log-rank test, P <0.001). Conclusions: Genetic testing should be considered in every patient with RCM where light-chain amyloidosis has been excluded. Survival remains poor regardless of etiology. Increased concentrations of GDF15, hs-TNT, NT-proBNP and pericardial effusion are associated with worse prognosis. Further studies are warranted.