A rare presentation of noncompaction cardiomyopathy (QF_SA_120)

Noncompaction cardiomyopathy is a rare congenital form of cardiomyopathy characterized by protruding trabeculations in the left ventricle with deep intertrabecular recesses. It has been previously associated with valvular pathologies and bradycardias.  We present a case of 34-year-old female patient who was initially seen at an outside hospital for lightheadedness and dizziness associated with anxiety.  An EKG was obtained, and she was found to have ventricular escape rhythm with a rate of 50 beats per minute with left bundle-branch morphology. She was subsequently transferred to our hospital for a higher level of care and further workup. High sensitivity troponin was repetitively negative on admission. Further history from the patient revealed that she also had experienced syncopal episodes in high school but did not have any since. In our hospital, continuous rhythm monitoring showed intermittent sinus bradycardia with left bundle-branch morphology with episodes of accelerated junctional rhythm.  A treadmill stress test was done to assess for chronotropic incompetence, our patient reached 10 METs after exercising for 8 minutes 25 seconds, however she could not reach target heart rate.

Diagnostic Techniques and Their Most Important Findings:

After excluding common causes of bradycardia in young patients and initial echocardiography exam showing apical trabeculations, cardiac MRI was obtained to confirm the suspected diagnosis noncompaction cardiomyopathy.   Cardiac MRI showed a left ventricular systolic function of 45%, increased size of the ventricular cavity and reduced LV mass.  There was no late gadolinium enhancement, myocardial walls were seen and the noncompaction to compaction tissue ratio was higher than 2.3:1. RV was normal.   His findings were consistent with the current criteria of diagnosis of noncompaction cardiomyopathy.

Learning Points from this Case:

Noncompaction cardiomyopathy is a congenital form of cardiomyopathy that has a variable manifestation. Its prevalence is estimated between 0.014 to 1.3 percent. While the majority of the patients can be relatively asymptomatic, heart failure, atrial and ventricular arrhythmias, sudden cardiac death and thromboembolic events have been associated with this diagnosis.
Different criteria have been developed to establish a diagnosis of noncompaction cardiomyopathy. They emphasize hyper-trabeculation, presence of a compacted and non-compacted layer of myocardium and color Doppler evidence of low within the intertubercular recesses.
Cardiac magnetic resonance (CMR) can be used to diagnose noncompaction cardiomyopathy echocardiographic findings are inconclusive. CMR criteria require a trabeculated LV mass with a maximum end-diastolic non compacted to compacted myocardial thickness ratio of higher than 2.3.