TTN and familial dilated cardiomyopathy: To determine the mechanism of diastolic dysfunction, the maximum tension amplitude, length dependence of maximum force, and the rates of tension development and relaxation were measured in DCM samples carrying mutations in TTN (p. R23464T fs*41 and p. Y18923*), TNNI3 (K36Q), TNNC1 (G159D) and MYH7 (E1426K).