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UCSF Cardiology
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Department of Medicine

Faculty Spotlight: Gregory Marcus, MD

Photo credit: Elizabeth Fall

Is alcohol good or bad for the heart? The short answer: it depends, it.s complicated, and Dr. Gregory Marcus is trying to find out more.

"Alcohol is fascinating as it relates to cardiovascular health," said Dr. Marcus, a cardiac electrophysiologist who studies atrial fibrillation, an abnormal heart rhythm in which the upper chambers of the heart quiver ineffectively, rather than pumping blood efficiently. "On one hand, there's evidence that moderate alcohol consumption might prevent heart attacks, be beneficial in heart failure, and help the cholesterol profile. Also, red wine might have beneficial components like antioxidants, which can help the health of blood vessels.

"On the other hand, there's pretty good evidence that alcohol increases risk for atrial fibrillation and may raise blood pressure," said Dr. Marcus. However, some of the data is anecdotal, drawn from clinical experience of so-called "holiday heart syndrome," in which patients develop atrial fibrillation after drinking, often following a holiday or weekend.

"The question is, is alcohol just triggering atrial fibrillation in those who already have the disease, or is it actually causing atrial fibrillation?" asked Dr. Marcus. "That's one of the things we need to figure out." He and his team hypothesize that there may be two dynamics at play: an acute effect, caused by a specific drinking episode, and a chronic effect, which unfolds over years of drinking.

Alcohol and Atrial Fibrillation

Although about 85 percent of Americans drink alcohol, little is known about how it affects the electrical properties of the heart. At the same time, while atrial fibrillation is the most common arrhythmia, how it develops is poorly understood. Dr. Marcus recently received a grant from the National Institutes of Health (NIH) to discover more about both these areas. "If we could really understand the mechanisms by which alcohol leads to atrial fibrillation, we might learn something that could reveal a new target for therapies," he said.

The grant includes several projects:

Additional Investigations

Dr. Marcus also leads other related studies:

All these studies underscore the need to understand more about the relationship between alcohol consumption and heart health, as well as how arrhythmias develop. "If we could understand which patients are prone to what heart conditions, and knew exactly how alcohol affects the heart, we could personalize our recommendations," said Dr. Marcus. "We might say, 'Mr. Smith, you would do better if you drank one to two glasses of wine a night,' or 'Mr. Jones, you should avoid alcohol.' But we don't yet know the answer, and we're very interested in figuring that out."

An Ideal Study

If he had unlimited funds, Dr. Marcus would like to conduct a randomized controlled trial — the "gold standard" of research. The study would enroll volunteers who would be willing to either drink alcohol or not, and randomize them to either a moderate drinking group or a non-drinking group. "If we had sufficient funding to enroll thousands of people and follow them for at least five years, that would be an outstanding opportunity to learn a lot about the relationship between alcohol and heart disease," said Dr. Marcus.

The Health eHeart Study may provide an infrastructure to support such an ambitious study, using mobile health apps, smartphone messaging, and other tech tools to gather a rich pool of data. "This would be a completely innovative and very clinically meaningful research study," said Dr. Marcus, noting that randomized controlled trials are the best way to answer research questions. For example, a large, randomized controlled trial run by the Women's Health Initiative found in 2002 that hormone replacement therapy was more likely to harm than help women, overturning the conventional wisdom at the time.

"An alcohol randomized study would be of interest far beyond cardiovascular health, gathering a humongous wealth of information that would be of interest to oncologists, gastroenterologists, endocrinologists, psychiatrists and many others," said Dr. Marcus.

Health eHeart Collaborations

In addition to his investigations about alcohol and heart disease, Dr. Marcus is enthusiastic about the growing scope of the Health eHeart Study, which he co-directs along with Dr. Olgin and Dr. Mark Pletcher, a cardiovascular epidemiologist. The study has enrolled participants from every state, as well as six continents and about 90 countries.

"We are very excited by President Obama's Precision Medicine Initiative that he mentioned in this year's State of the Union address, and think that what we're building is exactly what they're looking for," said Dr. Marcus. "The Health eHeart Study is not just a cohort study, but a new paradigm for collecting clinical research." Dr. Olgin has been invited to be a member of the President's and NIH panel for this Precision Medicine Initiative.

Dr. Marcus and his team are collaborating with a number of other institutions, including UC Berkeley, the Childhood Cancer Survival Study and the Duke Clinical Research Institute. The Health eHeart Study also has established a close working relationship with the American Heart Association (AHA), which prominently featured the study at its most recent annual meeting, and helped enroll several thousand participants. In collaboration with EmPowered to Serve, an AHA initiative that works with faith-based and community partners, the Health eHeart Study is recruiting more participants from underrepresented groups while providing tailored aggregate recommendations for community leaders about opportunities for members to improve their health.

The Health eHeart Study also works with the Patient-Centered Outcomes Research Institute, a federally funded organization that promotes patient involvement in research studies. Led by Dr. Pletcher, the recently formed Health eHeart Alliance convened a patient-investigator summit with about 50 patients and 20 researchers. Together they developed ideas for patient-initiated research questions, such as creating a smartphone-based algorithm to help determine the triggers for a particular patient's atrial fibrillation.

Driven by Curiosity

Dr. Marcus grew up in Berkeley, and majored in philosophy at UC San Diego. He also took pre-med classes, and wrote his honors thesis on medical ethics. "I wanted there to be meaning in my life, and felt that saving lives was the simplest way to do that," he said.

After earning his medical degree at George Washington University in Washington, DC, he completed his residency and chief residency at Stanford University. He did his cardiology and cardiac electrophysiology fellowships at UCSF, where he also earned a master's degree in clinical research. Dr. Marcus joined the UCSF faculty in 2006. In addition to his research, Dr. Marcus sees patients in clinic, performs ablation procedures, and implants pacemakers and defibrillators.

Dr. Marcus has a son in his 20s, and he and his wife, Jenny, have two young daughters. In addition to medicine and spending time with his family, Dr. Marcus enjoys playing basketball, skiing, and playing the drums.

"I've always been very curious," said Dr. Marcus. "I question things when the answer is, 'Well, that's just the way it is.' There's got to be a reason, and if we don't know it, it's just because we haven't figured it out yet. I love solving puzzles and challenging conventional wisdom."