Cardiomegaly is the term used to describe enlargement of the heart, which is a condition that usually occurs secondary to another condition. The most common causes are heart disease and high blood pressure (hypertension). The medication used to combat high blood pressure (antihypertensive medication) can cause side effects, and this article aims to outline these potential complications.¹

Introduction

Antihypertensive drugs can work systemically (affecting the whole body), or they can work specifically on the nervous system; either on the central nervous system (CNS), the peripheral nervous system, or on both simultaneously. The location of action depends on the class of antihypertensive drug. 

Cardiomegaly is medically defined when the diameter of the heart is more than 50% of the diameter of the chest cavity. When your blood pressure is high, your heart is working extra hard to function properly. This can cause the shape of your heart to change, resulting in cardiomegaly. Antihypertensive drugs work to decrease blood pressure, which can in turn work to reduce the stress on the heart and avoid further blood pressure-induced damage to the organ.²

Blood pressure definition and classes of antihypertensive medications

Systolic blood pressure is the pressure recorded when the heart pumps blood out to the rest of the body, whereas diastolic blood pressure is recorded when the heart relaxes. Blood pressure is recorded as systolic blood pressure over diastolic blood pressure. 

Normal blood pressure is 120/80. Different stages of increased blood pressure can be defined depending on the systolic and diastolic blood pressure.

• An elevated blood pressure is systolic at 120-129 and diastolic at 80 or below 
• Stage 1 hypertension is when the systolic blood pressure is 130-139 or the diastolic pressure is 80-89
• Stage 2 hypertension is when the systolic blood pressure is at least 140 or the diastolic pressure is at least 90
• A hypertensive crisis is defined as systolic blood pressure over 180 and/or diastolic blood pressure over 120

Common classes of antihypertensive drugs are:

• Angiotensin-converting enzyme (ACE) inhibitors: they widen and relax your blood vessels
• Angiotensin II receptor blockers (ARBs): they relax your blood vessels
• Beta-blockers: they work by slowing down your heart rate
• Calcium channel blockers: they relax your blood vessels
• Diuretics: they reduce the fluid volume in your bloodstream

When initially diagnosed with hypertension, you should be prescribed antihypertensives according to certain criteria, such as age and diabetic status. This is because some antihypertensive drugs work best within specific patient demographics. For example, the choice of antihypertensives in diabetic patients is ACE inhibitors.³

Common side effects of antihypertensive medications

The use of antihypertensives can lead to several side effects. Common side effects include tiredness, muscle pain and poor sleep. Managing side effects is important as adherence to blood pressure medication can be affected by patients experiencing these unpleasant side effects.

Specific side effects will differ from patient to patient and will depend on the class of antihypertensive being taken. It will also depend on whether you have any other existing conditions in addition to the heart problems, such as diabetes or kidney disease. 

Other factors that influence side effects in people with cardiomegaly are the heart’s reduced functionality in pumping blood around the body, and whether you are already on other medications that can interact with the antihypertensive drugs.⁴

Side effects by medication class

ACE inhibitors

ACE inhibitors can be recognised by the suffix -pril, e.g. ramipril or lisinopril. ACE inhibitors work by blocking angiotensin II, a hormone that constricts blood vessels, thereby increasing blood pressure. Therefore, when angiotensin II is blocked, the constriction of blood vessels is decreased. Common side effects caused by ACE inhibitors include:⁵

• Dry cough
• High levels of potassium in the blood
• Swelling
• Risk of damage to the kidneys, specific to those with cardiomegaly, which can affect their function

Angiotensin receptor blockers (ARBs)

Angiotensin II receptor blockers (ARBs) can be recognised by the suffix -sartan, e.g. lorsartan or candesartan. Like ACE inhibitors, ARBs work by blocking angiotensin II. Common side effects caused by ARBs include:⁶

• Dizziness
• High levels of potassium in the blood
• Tiredness
• Risk of damage to the kidneys, specific to those with cardiomegaly

Beta-blockers

Beta-blockers can be recognised by the suffixes -alol or -olol, e.g. labetalol or bisoprolol. They work to reduce blood pressure by controlling the stress hormones adrenaline and noradrenaline. Common side effects caused by beta-blockers include:⁷

• Slowed heart rate (known as bradycardia) 
• Feeling cold in your extremities
• A risk of increasing or triggering heart failure in patients with cardiomegaly

Calcium channel blockers

Most calcium channel blockers can be recognised by the suffix -dipine, such as amlodipine or nifedipine. Diltiazem and verapamil are two other widely utilised calcium channel blockers. Calcium channel blockers work to lower blood pressure by controlling entry of calcium into heart cells. Common side effects caused by calcium channel blockers include:⁸

• Dizziness
• Headaches
• Swelling
• A risk of increasing or triggering heart failure in people with cardiomegaly
• A risk of developing fluid retention

Diuretics

There are different types of diuretics, with loop diuretics (e.g. furosemide) or thiazide diuretics (e.g. indapamide) being the most widely utilised. Diuretics work to adjust the amount of sodium and water lost in urine, which, in turn, works to lower your blood pressure. Common side effects caused by diuretics include:⁹

• Muscle cramps
• Dehydration (can lead to reduced blood volume in people with cardiomegaly
• Imbalance of electrolytes, such as potassium or sodium

Special considerations for patients with heart enlargement

It is important to monitor your blood pressure if you have heart enlargement. This is not only to avoid hypertension-related organ damage, but to prevent further disease progression.¹⁰

Combination therapy is commonly utilised in the treatment of hypertension, i.e. you are put on more than one antihypertensive drug at a time. There is evidence to show that a beta-blocker in combination with the use of an ACE inhibitor can reduce the risk of heart failure and death in people with decreased cardiac output.¹¹

Management and monitoring of side effects

When taking antihypertensive drugs, the best way to reduce side effects and improve medication compliance is to continually monitor blood pressure, heart rate and kidney function while taking the medication. 

You should consider implementing non-medical changes, such as lifestyle modifications. These could include:

• Maintaining a healthy diet
• Increasing physical activity levels
• Weight management
• Smoking cessation
• Avoiding excessive alcohol intake

These changes could work to improve your blood pressure when living with or without hypertension, and potentially alleviate the need to take medication.¹²

Summary

The most common classes of antihypertensive drugs are ACE Inhibitors, ARBs, beta-blockers, calcium channel blockers and diuretics. The side effects caused by antihypertensive drugs in people with enlarged hearts depend on the class of drugs. Side effects range from dry cough, varying levels of electrolytes in the blood, swelling, headaches, and increased risk of developing heart or kidney failure. Due to the varying nature when multiple diseases occur simultaneously (comorbidities), it is important that you receive a personalised treatment plan. These would work effectively to reduce side effects caused by using antihypertensive drugs, thereby improving your quality of life and reducing the progression of heart enlargement.