Titin-Related Dilated Cardiomyopathy: The Sequence of Events and The Role of Circulating Biomarkers in The Clinical Assessment

Titin truncating variants ( TTN tv) are known as the leading cause of inherited dilated cardiomyopathy (DCM). Nevertheless, the clinical course is not fully understood and it is unclear whether circulating cardiac biomarkers are helpful in the detection and risk assessment. We sought to assess: 1) early signs of cardiotitinopathy including serum biomarkers: high-sensitivity cardiac troponin T (hs-cTnT) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) in clinically stable patients, and 2) indicators of outcome among TTN tv carriers. Our single-centre cohort included 108 carriers (including 70 DCM patients) from 43 families. Clinical, laboratory and follow-up data were analyzed. The earliest abnormality was left ventricular dysfunction, present in 8, 26 and 47% of patients in the 2nd, 3rd and 4th decade of life, respectively. It was followed by symptoms of heart failure and elevation of NT-proBNP, linked to severe (persistent or transient) left ventricular systolic dysfunction, and later by arrhythmias, preceding both malignant ventricular arrhythmia (MVA) and end-stage heart failure (esHF). Hs-cTnT serum levels were increased in the late stage of the disease only. During the median follow-up of 5.2 years both MVA and esHF occurred in 12% of TTN tv carriers. In multivariable analysis, NT-proBNP level ≥650 pg/ml was the best predictor of both composite endpoint (MVA and esHF), and of MVA alone. We conclude that assessment of circulating cardiac biomarkers is not useful in the detection of cardiotitinopathies but may be helpful in the risk assessment.