Approach to family screening (clinical evaluation and genetic testing) in first-degree relatives of a proband with hypertrophic cardiomyopathy

HCM: hypertrophic cardiomyopathy; ECG: electrocardiogram.
* Interpretation of pathogenicity may be revised as more data become available. UpToDate experts recommend seeking periodic updated information on mutation classification, particularly for a variant of unknown significance.
¶ Some experts prefer to screen with sarcomeric gene testing prior to clinical evaluation of first-degree relatives, but UpToDate experts start with clinical assessment.
Δ Consider cardiac magnetic resonance imaging if echocardiogram is nondiagnostic or if the ECG is abnormal and the echocardiogram is normal or otherwise ambiguous with respect to presence of increased left ventricular wall thickness.
◊ Cardiac imaging and ECG every one to two years in adolescents and then every three to five years until mid-life if evaluations remain normal.
§ HCM is diagnosed clinically when maximal left ventricular wall thickness is ≥15 mm anywhere in the left ventricular chamber in the absence of another cause of that degree of increased wall thickness, while lesser degrees of hypertrophy (13 or 14 mm) can also be consistent with HCM, particularly if patient has a family history of HCM.