Lamin A/C (LMNA) cardiomyopathy is an adult-onset, autosomal dominant, rapidly progressive cardiomyopathy which belongs to a spectrum of familial idiopathic cardiomyopathies. It is the most common type of familial dilated cardiomyopathy that is associated with conduction defects. A 76-year-old African American female with second-degree atrioventricular (AV) block presented for evaluation of persistent fatigue. Her family history was significant for sudden deaths of her son and brother at the age of 6 and 48 years, respectively, and AV block in her sister with a pacemaker implant at the age of 64 years. Physical examination was within normal limits. Electrocardiogram showed a Mobitz type II, second-degree AV block. Mild dilated cardiomyopathy was present on echocardiogram. Stress echocardiography had to be stopped due to premature ventricular contractions. Cardiac catheterization, coronary angiography, and cardiac MRI revealed no significant etiology for rhythm disturbance. Holter monitoring revealed intermittent bradycardia with a heart rate falling as low as 28 beats per minute, which led to the decision of dual-chamber pacemaker implantation. RhythmNext genetic testing (Ambry Genetics, Aliso Viejo, CA) was done due to the significant family history of sudden death; it revealed a heterozygous E203K pathologic mutation in the LMNA gene. Sudden death is the most common mode of death in LMNA cardiomyopathy; hence, the implantation of intracardiac cardioverter-defibrillator for primary prophylaxis was discussed with the patient. Clinicians should suspect LMNA cardiomyopathy in patients with rhythm disorders and family history of sudden death, which can help to identify individuals at risk and prevent sudden death by appropriate interventions.
Keywords: atrioventricular block; cardiomyopathy; lmna; pacemaker; sudden death.
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