INTRODUCTION: LMNA-related cardiomyopathy may manifest itself with a variable degree of left ventricular dysfunction, progressive conduction system disease which mainly involve atrioventricular node, atrial and ventricular tachyarrhythmias.
CLINICAL CASE: Woman, 46 years old, admitted to the emergency department for angina and subsequent syncope while she was driving. In anamnesis evidence of symptomatic bradycardia. A previous 24h ECG-Holter showed persistent junctional rhythm in absence of significant pauses. At ECG evidence of junctional rhythm, HR 42 bpm. At echocardiogram there was preserved biventricular systolic function. Midly increased HS-Tn. For the submitted clinic and symptomatic bradycardia in anamnesis, exercise test was performed which was positive for symptoms (chest oppression) and severe chronotropic incompetence. Subsequent coronary angiography showed normal coronary arteries. Then the patient underwent to head-up tilt test that resulted negative for syncope but positive for symptoms and chronotropic incompetence. On suspicion of conduction system pathology a ‘bedside’ SETE was performed that showed SSS (TRNSc 900 msec – fig.1) and an AV conduction disturbance (BAV I° with a persistent 400 msec long PR after isoprenaline iv – fig.2). To clarify the conduction system pathology genesis, cardiac-MRI was recommended (but declined) and genetic testing was done, which identified a pathogenetic mutation of LMNA-gene. Therefore, the patient underwent to dual-chamber PMK implantation and was included in a course of close follow-up in order to diagnose early myocardial involvement or ventricular tachyarrhythmias whose make necessary an up-grading to ICD.
DISCUSSION: The patient presented an unusual form of LMNA-related cardiomyopathy which clinical presentation included only symptomatic sick sinus syndrome for syncope; the absence of other clinical manifestations made diagnosis complex. This showed how important is sometimes to look for the mechanism behind a common disorder such as bradycardia in young patients with no apparent cardiovascular risk factors, also considering genetic testing in suspected cases.
CONCLUSION: This is a rare case of LMNA-related cardiomiopathy whose peculiarity is in the pathology of the conduction system, with a greater involvement of sinus node than atrioventricular node. This phenotype showed an unusual clinical presentation with an initial absence of cardiac muscle involvement.
