Clinical Findings of Hypertrophic Cardiomyopathy

The pathophysiology of hypertrophic cardiomyopathy (HCM) consists of dynamic left ventricular outflow tract obstruction (LVOTO), mitral regurgitation (MR), diastolic dysfunction, myocardial ischemia, arrhythmias, and autonomic dysfunction. 

For a given patient with HCM, the clinical outcome may be dominated by one of these components or may be the result of a complex interplay. Thus, it is prudent to consider the potential presence of such abnormalities in a comprehensive clinical evaluation and address their impact in the management of these patients.

The classic HCM patient has 4 clinical findings: 

1) Dynamic crescendo-decrescendo systolic murmur

i. best heard over the lower left sternal border

ii. radiates to axilla (not carotids)

iii. more audible with increased contractility/preload

iv. less audible with decreased preload, increased systemic resistance

2) Prominent apical point of maximal impulse

i. shifted laterally

ii. either bifid or trifid

3) Abnormal carotid pulse

i. Carotid double pulsation (pulsus bisferiens)

4) Fourth heart sound (S4)

These clinical findings are sequelae of LVOTO. Septal hypertrophy leads to narrowing of the LVOT. Subsequent abnormal flow dynamically displaces the mitral leaflets anteriorly during systole, further exacerbating the LVOTO. Furthermore, the anatomy of the mitral valve is also altered which makes the valve susceptible to mitral regurgitation and systolic LVOTO.

-TJ-

Reference:

Ommen SR, Mital S, Burke MA, Day SM, Deswal A, Elliott P, Evanovich LL, Hung J, Joglar JA, Kantor P, Kimmelstiel C, Kittleson M, Link MS, Maron MS, Martinez MW, Miyake CY, Schaff HV, Semsarian C, Sorajja P. 2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation. 2020 Dec 22;142(25):e558-e631. doi: 10.1161/CIR.0000000000000937. Epub 2020 Nov 20. Erratum in: Circulation. 2020 Dec 22;142(25):e633. PMID: 33215931.