A Study of ARRY-371797 in Patients With LMNA-Related Dilated Cardiomyopathy

Key Inclusion Criteria: * Patients with idiopathic dilated cardiomyopathy and stable New York Heart Association (NYHA) Class II - IIIa congestive heart failure (CHF). * Stable, guidelines-based medical and device therapy, without any CHF hospitalizations or change in heart failure drug dose with ≥ 50% reduction in dose or ≥ 100% increase in dose in the past 3 months. * Left ventricular (LV) end diastolic diameter by trans-thoracic echocardiography of \> 3.3 cm/m2 (for females) or 3.4 cm/m2 (for males) and/or LV ejection fraction ≤ 45%. * Gene positive for a pathogenic mutation in the LMNA gene, as determined by a CLIA-certified clinical laboratory (mutations including but not limited to: splice-site, non-sense, deletion mutations, a mis-sense mutation in a highly conserved codon, a mis-sense mutation involving a major charge change, a mis-sense mutation previously associated with genetic dilated cardiomyopathy). * Within 3 weeks prior to first dose of study drug, completed distance during six minute walk test of ≥ 100 m and ≤ 350 m AND/OR ≥ 100 m and ≤ 450 m AND ≤ 60% predicted distance AND patient is symptomatic for dilated cardiomyopathy per Investigator judgment. * On the day before and day of first dose of study drug, completed distance during six minute walk test of ≥ 100 m and ≤ 400 m (with the greater value within 10% of the lesser value) AND/OR ≥ 100 m and ≤ 475 m (with the greater value within 10% of the lesser value) AND patient is symptomatic for dilated cardiomyo…