Why digoxin and amlodipine is contraindicated in HOCM ?
Hypertrophic Obstructive Cardiomyopathy (HOCM) is a condition characterized by abnormal thickening of the heart muscle, especially the left ventricle, which can lead to various hemodynamic changes and clinical manifestations. The contraindication of certain medications like digoxin and amlodipine in HOCM is due to their potential effects on the heart and the specific pathophysiology of HOCM:
- Inotropic Effects: Digoxin is a medication that increases the contractility (inotropic effect) of the heart muscle. In HOCM, where there is already increased contractility and potential outflow tract obstruction due to hypertrophy, further increasing contractility can exacerbate the obstruction and worsen symptoms.
- Heart Rate Effects: Digoxin can also decrease heart rate. In HOCM, a slower heart rate can lead to longer diastolic filling time, which can increase the degree of left ventricular outflow tract obstruction and worsen symptoms.
- Vasodilation and Blood Pressure Effects: Amlodipine is a calcium channel blocker that causes vasodilation and helps lower blood pressure. However, it can cause systemic vasodilation and potentially reduce preload (the amount of blood entering the heart during diastole). In individuals with HOCM, who often have reduced preload due to the obstruction, further reducing preload can worsen the outflow tract obstruction and potentially exacerbate symptoms.
In HOCM, the primary concern is to reduce the obstruction of blood flow out of the left ventricle and improve diastolic filling. Medications that may worsen outflow tract obstruction, alter heart rate, or significantly affect preload are generally avoided or used with caution to prevent exacerbation of symptoms and potential complications.
The management of HOCM often involves a tailored approach, which may include beta-blockers, calcium channel blockers of certain types (like verapamil or diltiazem), or specific therapies aimed at reducing obstruction and improving diastolic filling. It’s crucial for individuals with HOCM to receive personalized treatment based on their unique clinical situation and under the guidance of their healthcare provider.