Acute Hypotension Management in Obstructive Hypertrophic Cardiomyopathy (HCM)

Introduction

Hypertrophic cardiomyopathy (HCM) is a condition that requires careful management, with guidelines supported by the American College of Cardiology, the European Society of Cardiology, and the American Heart Association 1, 2, 3

The American College of Cardiology recommends intravenous phenylephrine as first-line treatment for acute hypotension in patients with obstructive HCM who do not respond to fluid administration 4, 5
Beta-blockers or non-dihydropyridine calcium channel blockers are recommended as first-line therapy for patients with HCM presenting with symptoms such as exertional angina or dyspnea, as suggested by the American College of Cardiology 3

Phenylephrine IV is the first choice for vasoconstrictor therapy, increasing afterload and reducing LVOT gradient 4
The American College of Cardiology recommends administering phenylephrine intravenously (or other vasoconstrictors without inotropic activity), alone or in combination with beta-blockers, especially when there is no response to fluid administration in patients with HCM and associated hypotension due to gastrointestinal bleeding 5

The American College of Cardiology recommends targeting a heart rate of less than 60-65 bpm using IV beta-blockers 4
Non-vasodilating beta-blockers are the first-line therapy for symptomatic LVOT obstruction, due to their ability to reduce heart rate, prolong diastolic filling, and improve myocardial contractile protein inactivation, as recommended by the European Society of Cardiology and the American College of Cardiology 1, 2, 5

The American College of Cardiology suggests considering cardioversion for unstable arrhythmias, such as atrial fibrillation 6
Anticoagulation with direct-acting oral anticoagulants is recommended as first-line therapy for patients with atrial fibrillation, regardless of CHA₂DS₂-VASc score 3
Rate control can be achieved with beta-blockers, verapamil, or diltiazem based on patient preference and comorbidities 3

Septal reduction therapy, including surgical myectomy or alcohol septal ablation, should be considered if symptoms persist despite optimal medical therapy, with surgical myectomy preferred for younger patients with thicker septum and alcohol septal ablation as an alternative for older patients or those with contraindications to surgery 1, 2, 3, 6
Apical myectomy may be considered in highly selected patients with apical HCM with severe symptoms in specialized centers 3

Cardiac myosin inhibitors, such as mavacamten, improve LVOT gradients, symptoms, and functional capacity in 30-60% of patients, but require risk evaluation and mitigation strategy due to potential decrease in LVEF <50%, as noted by the American College of Cardiology 5
ACE inhibitors and ARBs have a benefit that is not well established for patients with HCM, as stated by the American College of Cardiology 3
Digoxin is contraindicated due to its positive inotropic effects, which can worsen LVOT obstruction, as stated by the European Society of Cardiology 1
Dihydropyridine calcium channel blockers, such as nifedipine, are also contraindicated due to their potential to exacerbate LVOT obstruction, as warned by the American College of Cardiology 2
Disopyramide is recommended as add-on therapy to beta-blockers in patients with persistent symptoms, with a Class I recommendation (Level B evidence) when added to beta-blockers for symptomatic LVOT obstruction, due to its negative inotropic effect which reduces outflow tract gradient 1, 7, 3, 6

Transthoracic echocardiogram (TTE) should be performed every 1-2 years to assess the degree of myocardial hypertrophy, dynamic LVOT obstruction, mitral regurgitation, and myocardial function in patients with HCM, according to the American Heart Association 3
12-lead ECG and 24-48 hour ambulatory monitoring should be performed in initial evaluation and every 1-2 years, as recommended by the American Heart Association 3
QTc interval monitoring is required when using disopyramide, with a reduction in dose if the QTc interval exceeds 480 ms, and patients should be watched for anticholinergic side effects such as dry eyes, mouth, urinary hesitancy, and constipation 1

Fluid management is important, and patients should avoid dehydration and excess alcohol consumption, as recommended by the European Society of Cardiology 1
Weight management is also crucial, and overweight patients should be encouraged to lose weight, as suggested by the European Society of Cardiology 1
Low-intensity aerobic exercise is reasonable as part of a healthy lifestyle, and comorbidities, such as hypertension, diabetes, hyperlipidemia, and obesity, should be treated according to relevant guidelines, as recommended by the American College of Cardiology 2, 4
Evaluation for sleep apnea and appropriate treatment is necessary, as this can worsen both cardiac function and metabolic parameters, according to Diabetes Care in 2020 8

A multidisciplinary approach involving cardiology, obstetrics, and anesthesiology is recommended for obstetric patients with HOCM, and avoiding hypotension during delivery is advised, according to the American College of Cardiology 5
Epidural and general anesthesia are acceptable for obstetric patients with HOCM, with careful hemodynamic management, as suggested by the American College of Obstetricians and Gynecologists 5
The following hypotension management algorithm is recommended for patients with HOCM undergoing anesthesia: