Restrictive cardiomyopathy (RCM) is a rare childhood cardiomyopathy that is a challenging diagnostic problem for clinicians. We describe a case of an 8-year-old girl with a 2-year history of shortness of breath on exertion. Electrocardiogram and echocardiography showed biatrial enlargement, while cardiac magnetic resonance showed biatrial dilation and normal pericardial thickness. Left and right heart catheterization revealed a left ventricular (LV) end-diastolic pressure (EDP) of 20 mmHg, right ventricular (RV) EDP of 13 mmHg, and pulmonary arterial systolic pressure of 51 mmHg. LV and RV pressure traces showed that LV and RV pressures moved concordantly with respiration, and that the systolic area index was 0.98. Cardiac catheterization data were therefore supportive of RCM. Next-generation sequencing identified a heterozygous variant of the troponin I gene (TNNI3; c.574C>T). Combining these findings led to a diagnosis of RCM. The patient's parents chose conservative treatment, but at the 12-month follow-up she died of worsening heart failure and cerebral infarction. This case emphasizes the need for cardiac catheterization and genetic testing in RCM, and suggests that anticoagulants should be recommended to reduce the risk of thromboembolic events.
Keywords: Restrictive cardiomyopathy; TNNI3; cardiac catheterization; case report; genetics; mutation.