From the Guidelines
Hypertrophic cardiomyopathy (HCM) is characterized by a harsh crescendo-decrescendo systolic murmur due to systolic anterior motion (SAM) of the mitral valve with left ventricular outflow tract obstruction (LVOTO), as stated in the 2024 AHA/ACC/AMSSM/HRS/PACES/SCMR guideline for the management of hypertrophic cardiomyopathy 1. The presence of this murmur is a key diagnostic feature, and its intensity can be influenced by various maneuvers.
- The murmur is typically best heard at the left lower sternal border and apex.
- It intensifies with maneuvers that decrease preload or afterload, such as the Valsalva maneuver or standing from a squatting position, as these maneuvers worsen the obstruction by bringing the septum and anterior mitral valve leaflet closer together.
- Conversely, the murmur decreases with maneuvers that increase preload or afterload, such as squatting or handgrip exercises. Some patients may also have a mitral regurgitation murmur due to systolic anterior motion of the mitral valve.
- The intensity of the murmur correlates with the degree of obstruction, though some patients with non-obstructive HCM may have minimal or no murmur. During physical examination, clinicians should perform provocative maneuvers, such as the Valsalva maneuver, to elicit or intensify the murmur, as this helps distinguish HCM murmurs from other cardiac conditions, as recommended in the 2024 guideline 1.
From the Research
Murmur in Hypertrophic Cardiomyopathy
- Hypertrophic cardiomyopathy (HCM) is a condition characterized by thickening of the heart muscle, which can lead to obstruction of blood flow and symptoms such as chest pain, shortness of breath, and fainting 2, 3.
- A murmur is a common finding in patients with HCM, and is typically caused by turbulence of blood flow as it passes through the narrowed left ventricular outflow tract (LVOT) 4.
- The treatment of HCM depends on the severity of symptoms and the presence of obstruction, and may include medications such as beta blockers, calcium channel blockers, and disopyramide, as well as procedures such as septal ablation or surgical myectomy 2, 3, 5.
- Disopyramide is a medication that has been shown to be effective in reducing symptoms and improving quality of life in patients with obstructive HCM, although it may not be effective in all patients 2, 3, 5.
- Factors that predict responsiveness to disopyramide include better left ventricular systolic function, less mitral regurgitation, and smaller left ventricular size 5.
- Beta blockers and verapamil are also commonly used to treat HCM, and have been shown to be effective in reducing symptoms and improving outcomes, although the choice of medication depends on individual patient characteristics and preferences 6.
Treatment Options
- Disopyramide: reduces symptoms and improves quality of life in patients with obstructive HCM, although may not be effective in all patients 2, 3, 5.
- Beta blockers: effective in reducing symptoms and improving outcomes in patients with HCM, and are often used as first-line therapy 6.
- Verapamil: may be used as second-line therapy in patients with HCM, although its effectiveness and safety compared to beta blockers is not well established 6.
- Septal ablation or surgical myectomy: may be considered in patients with severe obstruction and symptoms that are not responsive to medical therapy 2, 3, 5.