Enlarged Heart
An enlarged heart, medically known as cardiomegaly, is a condition where the heart is larger than normal on imaging studies such as chest X-rays or echocardiograms. This enlargement can involve the entire heart or specific chambers and typically develops as a response to increased workload or damage to the heart muscle. Cardiomegaly is not a disease itself but rather a sign of an underlying condition such as heart failure, high blood pressure, heart valve disease, or cardiomyopathy. The enlarged heart may struggle to pump blood efficiently, potentially leading to serious complications if the underlying cause is not addressed.
What is it?
The heart consists of four chambers—two upper chambers (atria) and two lower chambers (ventricles). In a healthy adult, the heart is approximately the size of a closed fist. Cardiomegaly develops through two main mechanisms: hypertrophy, where the heart muscle walls thicken in response to increased pressure or workload, increasing the mass of the heart but not necessarily the chamber size; and dilation, where the heart chambers expand and enlarge, often due to volume overload or weakened heart muscle. The left ventricle, which does the most work pumping blood to the body, is the chamber most commonly affected by enlargement.
Common causes of an enlarged heart include chronic high blood pressure (hypertension), which forces the heart to work harder to pump blood, causing the left ventricle to thicken; coronary artery disease and previous heart attacks, which damage heart muscle and cause the heart to enlarge as it tries to compensate; heart valve disease such as aortic stenosis, aortic regurgitation, or mitral regurgitation, which forces the heart to work harder; cardiomyopathy (diseases of the heart muscle itself) including dilated cardiomyopathy where the heart chambers enlarge and weaken, hypertrophic cardiomyopathy where the muscle thickens abnormally, and restrictive cardiomyopathy; chronic lung disease causing increased pressure in the right side of the heart; anemia causing the heart to pump faster and harder to deliver adequate oxygen; thyroid disorders (both overactive and underactive thyroid); excessive alcohol consumption; pregnancy-related cardiomyopathy; viral infections of the heart (myocarditis); and genetic factors. Athletes who engage in intense endurance training can develop “athlete’s heart”—a benign form of cardiac enlargement that is adaptive rather than pathological and reverses with detraining.
Important to Know
Many people with mild cardiac enlargement have no symptoms, particularly in early stages. As the condition progresses or the underlying cause worsens, symptoms may develop including shortness of breath, initially with exertion and later at rest or while lying flat; fatigue and reduced exercise tolerance; swelling (edema) in the legs, ankles, and feet; swelling in the abdomen (ascites); irregular heartbeat or palpitations; dizziness or lightheadedness; chest pain or discomfort, particularly if caused by coronary disease; and persistent cough or wheezing, especially when lying down. Diagnosis begins with chest X-ray, which provides a simple assessment of heart size using the cardiothoracic ratio (heart width compared to chest width—normally less than 50%). Echocardiography is the key diagnostic tool, using ultrasound to visualize heart chambers, measure wall thickness and chamber dimensions, assess pumping function (ejection fraction), and evaluate heart valves. Additional tests may include electrocardiogram (EKG) to detect rhythm abnormalities and signs of hypertrophy, stress testing to assess heart function during exertion, cardiac CT or MRI for detailed anatomical assessment, blood tests to check for anemia, thyroid problems, or markers of heart stress (BNP), and cardiac catheterization if coronary disease is suspected. Treatment focuses on addressing the underlying cause: for hypertension, aggressive blood pressure control with medications (ACE inhibitors, ARBs, beta-blockers, diuretics); for coronary disease, medications and potentially revascularization; for heart failure, a combination of medications to reduce heart workload and improve function; for valve disease, surgical repair or replacement when indicated; and for cardiomyopathy, disease-specific treatments which may include medications, implanted devices, or in severe cases, heart transplantation. Lifestyle modifications are crucial for all patients: sodium restriction (typically under 2000 mg daily), fluid restriction if heart failure is present, limiting alcohol consumption or abstaining entirely, regular moderate exercise as tolerated and approved by physician, weight management, smoking cessation, and stress reduction. In some cases, devices may be needed: implantable cardioverter-defibrillator (ICD) for those at risk of dangerous arrhythmias, cardiac resynchronization therapy (CRT) to improve heart contraction coordination, or ventricular assist devices in severe heart failure. Prognosis depends entirely on the underlying cause, severity of enlargement, degree of dysfunction, and response to treatment. Some causes like hypertension-induced hypertrophy can improve or stabilize with proper treatment, while others like advanced cardiomyopathy may progress despite optimal therapy. Regular monitoring, medication adherence, and lifestyle modifications are essential for managing this condition and preventing complications such as heart failure, arrhythmias, blood clots, and sudden cardiac death.