How to manage patients with hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a common and frequently inherited disease, with an estimated prevalence of 1/500. It is characterized by left ventricular myocardial thickening. HCM is a major cause of morbidity and mortality, including exertional symptoms, heart failure, atrial fibrillation, stroke and ventricular arrhythmias, potentially resulting in sudden cardiac arrest or death.A new guidance document on HCM for cardiovascular healthcare providers is now available from the Canadian Cardiovascular Society. It provides a broad overview of the clinical management of HCM, based on expert consensus and published evidence. The document is organized into the following main sections, with practical tips highlighted in each section:Diagnosis of HCMGenetic testing and family screeningImaging HCMScreening for arrhythmiaManagement of atrial fibrillation (discussed in more detail below)Management of obstruction and heart failure (discussed in more detail below), including what to do when medical therapy failsRisk stratification and prevention of sudden cardiac death. Management of atrial fibrillation Oral anticoagulation (warfarin or a direct oral anticoagulant) should be started in all patients with HCM and atrial fibrillation, in the absence of contraindications. Decisions regarding rate vs. rhythm control of atrial fibrillation in HCM is similar to non-HCM patients, with the following HCM-specific considerations:Rate control can be attempted with beta-blockers and/or nondihydropyridine calcium-channel blockers (verapamil or diltiazem). Digoxin is generally avoided, especially in obstructive HCM, due to its positive inotropic effects.Rhythm control can be attempted with sotalol, disopyramide or amiodarone. These antiarrhythmic drugs require monitoring for QT prolongation.Atrial fibrillation ablation, atrioventricular node ablation and pacemaker implantation are additional options. Management of obstruction and heart failureManagement of symptomatic obstruction requires a stepwise approach and includes lifestyle changes, pharmacologic therapy and invasive procedures: Educate patients about avoidance of hypovolemia and sudden changes in position.Avoid vasodilators (e.g. sildenafil, nitrates) and diuretics unless required.First-line pharmacotherapies are nonvasodilating beta-blockers (e.g., metoprolol) and/or nondihydropyridine calcium-channel blockers (verapamil, diltiazem).Second-line pharmacotherapies are disopyramide or a myosin inhibitor (mavacamten). Myosin inhibitors are effective and well tolerated in symptomatic obstructive HCM. Close monitoring of systolic function is required. They should not be used in patients with left ventricular ejection fraction (LVEF) < 55% and therapy should be interrupted if LVEF drops to < 50% during follow-up. Drug interactions with mavacamten are also discussed in the guideline. In the majority of cases, a beta-blocker will be used as primary therapy. If this is insufficient, then it is reasonable to add either disopyramide or mavacamten. Early reports indicate that mavacamten may have a more favourable side effect profile.When medical therapy fails, symptom relief may be achieved with surgical myectomy (adults or children) or alcohol septal reduction (adults only).Symptomatic nonobstructive HCM may be challenging to treat. Beta-blockers and/or nondihydropyridine calcium-channel blockers can be tried, and diuretics if filling pressure is elevated. Clinical trials of myosin inhibitors are ongoing.The guideline authors stress that the contents of this document reflect the consensus opinion of the writing committee based on published evidence as well as their collective experiences and should therefore be viewed as guidance rather than recommendations.Reference:Crean AM, Adler A, Arbour L, et al. Canadian Cardiovascular Society clinical practice update on contemporary management of the patient with hypertrophic cardiomyopathy. Can J Cardiol 2024:S0828-282X(24)00438-0. Published online June 13, 2024 ahead of print. (accessed June 25, 2024).

How to manage patients with hypertrophic cardiomyopathy

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