"Sola dosis facit venenum" is an old Latin proverb that means "the dose makes the poison", a conclusion that defines the basic principle of today’s toxicology.
Depending on the dose, everything can be both a poison and a remedy, and alcohol is no exception. The beneficial effects that low doses of alcohol have on the cardiovascular system have been appreciated since medieval times and the belief that a glass of red wine a day leads to better heart health has remained popular until this day.
Alcoholic cardiomyopathy (ACM) can lead to complications like heart failure and sudden cardiac death. Once the alcohol is removed from the system, heart function often improves and the prognosis is favorable. However, the risk of death for patients who don’t abstain from alcohol is greater than 50 percent.
What is alcoholic cardiomyopathy and why does it happen?
Cardiomyopathy (CM) is a group of heart muscle diseases accompanied by changes in the heart’s structure. That weakens the heart and reduces its ability to pump blood. There are many possible causes, ranging from genetic to acquired later in life. Regardless of the cause, cardiomyopathy usually presents as one of four types: dilated, hypertrophic, arrhythmic or restrictive.
Alcoholic cardiomyopathy is a result of long-term alcohol overconsumption, and makes up a third of all dilated cardiomyopathy cases. In this type, the left ventricle (the heart’s main pumping chamber) becomes enlarged. Its walls stretch (dilate) and become thinner, making it harder for the ventricle to contract and pump blood. The effects can then spread to the right ventricle, atria (the heart's upper chambers) and heart valves ("gates" between upper and lower chambers that ensure blood flows in one direction).
In higher doses, ethanol (drinking alcohol) is toxic for heart cells. Furthermore, the liver metabolizes ethanol into a substance called acetaldehyde, which is also toxic for the heart (and the liver). Both of these substances lead to the death of heart muscle cells and to changes in the way heart cells communicate with each other, as well as in their metabolism.
While this is true, the way in which alcohol can affect the heart shouldn’t be seen as isolated events of ethanol toxicity, considering that alcohol abuse affects the whole organism. Conditions that can accompany alcoholism — like vitamin B1 deficiency (beriberi disease) and liver cirrhosis — can also affect the heart.
How much alcohol is too much?
The criteria for heavy drinking differ for men and women, since we metabolize alcohol in different ways. It’s measured in standard drinks. A standard drink is 14 grams of alcohol, found in a 12-ounce bottle of beer, five ounces of wine, or 1.5 ounces of distilled spirits. Anything above four standard drinks a day or more than 14 a week for men, and three drinks a day or more than seven per week for women, is considered heavy drinking.
However, several studies suggested that an alcohol consumption of over 80 grams per day (so roughly six standard drinks) will, over the course of five years, damage heart cells through toxic mechanisms that lead to ACM.
What are the symptoms of alcoholic cardiomyopathy?
People with ACM might experience some of the following symptoms:
- Shortness of breath, especially with exertion (dyspnea). Dyspnea can manifest as feeling out of breath, having difficultly inhaling, or discomfort while breathing. Occasionally it’s followed by chest tightness or pain. The left ventricle pumps oxygen-rich blood arriving from the lungs to all other parts of the body. When it’s working at reduced capacity, it can’t pump all of the blood coming from the lungs, causing fluid build-up in the lungs. That disrupts the exchange of gases that allow your blood to become saturated with oxygen, leaving you with shortness of breath.
- Difficulty breathing when lying down. This might disrupt your sleep, causing you to wake up more frequently. The reason it gets worse in a horizontal position is gravity.
- Swelling of legs, ankles, feet or overall swelling. Fluid accumulates when the heart doesn’t have enough pumping power. You might notice this as rapid weight gain.
- Heart palpitations (irregular heartbeat) or rapid heartbeat (tachycardia). When the heart fails to meet the body's demands, it tries to compensate by beating faster, a condition known as tachycardia (heart rate above 100 beats per minute at rest). Tachycardia is one type of arrhythmia (heart rhythm disorder) characterized by abnormalities in heartbeats' timing and/or pattern. Arrhythmias are among the most common symptoms of cardiomyopathy, since changes in the heart’s structure have an impact on electrical signaling. This is especially common in ACM — alcohol itself causes arrhythmia even in the absence of CM.
- Fatigue, dizziness, and weakness. You might feel like everyday activities like climbing stairs or carrying groceries are becoming increasingly harder, or you might feel tired all the time. When there’s not enough oxygenated blood circulating the body, your heart redirects blood to the internal organs, leaving less oxygen for the muscles used to move your body. Since energy production depends on the presence of oxygen, that essentially makes every movement harder. This is a symptom of heart failure that gets worse as the disease progresses.
How is alcoholic cardiomyopathy diagnosed?
For a physician to make a diagnosis of alcoholic cardiomyopathy, they will ask you about your medical history, perform a physical exam, and order an imaging test.
- Physical exam. The doctor will take your blood pressure, check your heart rhythm and heart rate (looking for arrhythmia) and listen to your lungs (looking for wheezing and other sounds that indicate fluid accumulation). You will be asked about your alcohol consumption, and it’s important to be honest since your physician needs this information to come up with the best treatment plan.
- Laboratory tests. While patients might not always be honest about their drinking habits, their bloodwork always shows the truth. The diagnosis of alcoholic cardiomyopathy differs from other cardiomyopathies just by this laboratory test, meant to show the extent of damage caused by alcohol abuse. Levels of certain liver enzymes and their ratios can show chronic alcohol abuse. The test will probably measure carbohydrate-deficient transferrin (CDT), gamma-glutamyltransferase (GGT), glutamic oxalacetic transaminase (GOT), and glutamic pyruvic transaminase (GPT). Your doctor might also check for markers indicative of heart damage.
- Diagnostic imaging. Imaging is needed to confirm changes in the heart structure characteristic of cardiomyopathy. An ehocardiogram (heart ultrasound) and electrocardiogram (ECG, a test that shows electrical signaling in your heart) are most commonly used. Other imaging methods your doctor can choose include a chest X-ray, cardiac MRI, or CT scans.
How is alcoholic cardiomyopathy treated, and what’s the prognosis?
The prognosis is much more favorable than for dilated cardiomyopathy that has other causes. However, if patients with ACM continue to drink, the risk of death is high. For this reason, the most important part of ACM treatment is finding a suitable program designed to help people stop drinking.
Other parts of treatment focus on relieving the symptoms of heart failure and preventing complications. Depending on how far the disease has progressed, treatment can include:
- A low sodium diet, limiting fluid intake, and taking diuretics (water pills). These steps are meant to ease the strain that fluid accumulation has on your heart. Lower fluid levels can ease heart failure symptoms like breathlessness and swelling and reduce your blood pressure.
- Medications. Dilated cardiomyopathy (regardless of cause) can be treated with a combination of medications, depending on your symptoms. That can include ACE inhibitors to lower your blood pressure, beta-blockers to lower blood pressure and heart rate, anticoagulants (blood thinners) to prevent the formation of clots, or digoxin to strengthen the heart muscle contractions.
- Implantable cardioverter-defibrillators (ICDs) or other implantable devices. Irregular heart rhythms can sometimes be very dangerous and cause your heart to stop. If the arrhythmia can’t be regulated in another way, your physician might recommend an ICD, a device that monitors your heart rhythm and, if necessary, sends electrical shocks to control the heartbeat. Other devices that are considered are pacemakers or more rarely left ventricular assist devices (LVADs).