One or two drinks a day may make for a healthy heart, but people with atrial fibrillation (AFib) may experience immediate impacts, as a new study reveals.
University of California, San Francisco (UCSF) researchers found that alcohol immediately changed the electrical properties driving heart muscle contraction in patients undergoing a treatment for AFib. These subjects were randomised to receive an infusion of alcohol maintained at the lower limit of legal intoxication, An equal number of control subjects who instead received a placebo infusion did not have this occur. The work was published January 27, 2021 in the Journal of the American College of Cardiology: Clinical Electrophysiology,
Senior study author Gregory Marcus, MD, professor of medicine in the Division of Cardiology at UCSF explained: “The acute impact of exposure to alcohol is a reduction in the time needed for certain heart muscle cells in the left atrium to recover after being electrically activated and to be ready to activated again, particularly in the pulmonary veins that empty into the left atrium.”
AFib is the most common cardiac rhythm disorder, affecting some 1% of the world’s population, and is characterised by tachyarrhythmia. It is caused by abnormal electrical activity in the atria of the heart, making them fibrillate. This causes the atria to pump blood inefficiently, leading to feelings of the heart pounding, fluttering or skipping a beat. Due to turbulence caused by the irregular rhythm, a clot could form which could lead to a stroke. This results in some 158 000 deaths in the US annually. Other negative impacts include fatigue, weakness, dizzy lightheadedness, difficulty breathing and chest pain.
The study patients were undergoing a catheter ablation procedure. This is commonly used to suppress AFib by severing the electrical connection between the pulmonary veins and the left atrium. This areas was also the area noted to be affected by alcohol in the study.
Preparation for the ablation therapy required installation of catheters and electrodes in the heart chambers to monitor and pace the heart, and destroy selected tissue. The study measured refractory time before cells could again transmit electrical signals, and conduction speeds, as well as a stimulus inducing more AFib events. Electrical conduction speed and induced AFib events did not vary, but a 12 millisecond delay was seen in tissue around the pulmonary vein in the alcohol infusion group.
“Although epidemiological studies have found an association between self-reported alcohol consumption and the development of an atrial fibrillation diagnosis, ours is the first study to point to a mechanism through which a lifestyle factor can acutely change the electrical properties of the heart to increase the chance of an arrhythmia,” Marcus said. The same changes caused by alcohol infusion in the study have earlier been associated with episodes of AFib in previous computer models and animal studies, he said.
“Patients should be aware that alcohol can have immediate effects that are expected to increase risk for arrhythmias,” Marcus concluded.
However, in a separate study, injecting ethanol into the vein of Marshall when performing a catheter ablation seemed to increase the odds of treatment success compared to catheter ablation alone.