What Is a Cardiologist? Heart rhythm chart

A cardiologist is a physician who specializes in diagnosing and treating conditions affecting the cardiovascular system, which includes the heart, veins, arteries, and capillaries.

Cardiologists play a critical role in managing heart disease, the number one cause of death in the United States. According to the American Heart Association, heart disease caused 928,741 deaths domestically and around 19 million internationally in 2020 alone.

What Is a Cardiologist? Marcella Calfon-Press

Night and day, cardiologists like UCLA’s Marcella (Marcie) Calfon Press, MD, PhD, work to decrease those numbers — to save lives.

“We’re with patients in the scariest moments of their lives, their near-death situations,” she says.


A Day in the Life of Dr. Marcie Calfon Press, Interventional Cardiologist at UCLA Health

What Is a Cardiologist? Dr. Marcella Calfon Press working in the catheter lab

In addition to practicing cardiology, Dr. Press serves as associate clinical professor of cardiology, director of the Transcatheter Mitral Valve/TEER Program, associate director of the Interventional Cardiology Fellowship, and co-director of the UCLA Women's Cardiovascular Health Center.

Dr. Press says there’s no typical day for her. Generally, she sees patients, performs procedures, and then makes the rounds, checking on patients.

“There are usually days and blocks of time where I focus on either clinic, procedures, or hospital care,” she explains.

A day in Dr. Press’s life also involves family time.

“Being a mentor is also a big part of what I do,” she says. “I want to show trainees and students that you can be female and be a mom and still do everything I do.”

Women in Cardiology

Only about 4% of all practicing interventional cardiologists in the United States are women.

“When I was training, we didn’t have many female leaders in the field,” says Dr. Press. “I never knew another female interventional cardiologist.”

Dr. Press acknowledges the gender gap in cardiology is far from closed, but she also wants to celebrate progress.

“I think this is the best time to go into cardiology as a female. It can only be a strength for you.”

Increasing female representation in cardiology carries benefits beyond improving statistics. It could enhance the care of female cardiology patients.

“Heart disease is the number one killer in women,” says Dr. Press. “Women present later, have worse outcomes, and may often get misdiagnosed.”

In the video below, Dr. Press discusses the differences between heart disease in women and men.

Read More: Are first responders fully prepared to diagnose a heart attack in a woman? 

What Does a Cardiologist Do?

In general, cardiologists diagnose and treat heart conditions. However, numerous subspecialties exist within the field of cardiology. Each specialist does different things.

“There's almost nothing you can't do in cardiology. That's why it's an amazing field,” says Dr. Press.

Examples of distinct functional roles within cardiology include:

  • Interventional cardiologists, like Dr. Press, who use specialized procedures to diagnose and treat cardiovascular disease.
  • Cardiovascular radiologists, who use imaging technology to diagnose and monitor heart diseases.
  • Electrophysiologists, who help diagnose and treat conditions that affect the electrical system of the heart
  • Heart failure specialists, who work with transplant and end-stage heart failure patients.
  • Sports cardiologists, who help athletes better protect their hearts.
  • Critical care cardiologists, who see seriously ill patients. 
  • Researchers, who conduct experiments and oversee trials to discover new technologies and interventions.
  • Preventive internists, who promote overall heart health by encouraging exercise and nutrition and helping patients manage hypertension and cholesterol.

The quantity of distinct focus areas within cardiology speaks to the cardiovascular system’s complexity.

“People often think that heart attacks are the only things that can happen to the heart but in cardiology, we treat so many different heart conditions, especially as patients get older,” says Dr. Press.

She advises patients looking for cardiologists to seek trust, knowledgeability, and impeccable listening skills.

“You have to work together and build a relationship.”

(What Does a Cardiologist Do? Click the link to learn more...)

What Is a Cardiologist? Female cardiologist and her patient

What Does an Interventional Cardiologist Do?

Interventional cardiologists diagnose and treat cardiovascular conditions via specialized procedures, often involving catheters.

Interventional cardiology procedures include, but are not limited to:

  • Cardiac catheterization
  • Complex coronary angioplasty or stenting
  • Atherectomy
  • Myocardial biopsy
  • Transcatheter valve replacement and repair
  • Valvuloplasty

Interventional cardiologists often conduct life-saving procedures in emergency situations.

“There might be a heart attack patient on the brink of not surviving,” says Dr. Press. “An interventional cardiologist can open up a blood vessel, and suddenly, the patient can breathe again.”

These situations create unique bonds between interventional cardiologists and their patients. It’s something Dr. Press finds most rewarding about her field.

“I remember every heart attack patient I ever had,” she says. “You create intensely strong connections when you’re together, trying to fight for their life.”

What Is a Cardiologist? Cardiologist taking a patient's pulse

What’s the Difference Between a Cardiologist and an Electrophysiologist?

Dr. Press explains that understanding the difference between a cardiologist and an electrophysiologist starts with seeing the heart as three systems:

  • Pump (the muscle)
  • Electrical system
  • Circulatory system

Different subspecialties in cardiology focus on different systems. Cardiologists take care of the circulatory system and cardiac electrophysiologists take care of the electrical system.

“As an interventional cardiologist, I’m like a plumber. I make sure everything flows through the circulatory system and often make adjustments, such as repairing or replacing a valve,” Dr. Press explains. “Electrophysiologists are more like electricians. Their interventions focus on the heart’s electrical signals. They might put in pacemakers or treat arrhythmias via catheter ablation, for example.”

How to Become a Cardiologist

Cardiologists complete several years of training.

To become a cardiologist, you must complete medical school, residency training in internal medicine, (cardiology’s parent specialty), and training in a cardiology fellowship program, which usually lasts three years.

“You need to start with being a great internist and understand the heart in relation to every other system in the body,” Dr. Press says. “So many other systems work with the heart.”

Dr. Press fell in love with interventional cardiology during her fellowship program. She vividly remembers being in the cardiac catheterization (cath) lab, taking pictures of arteries and watching the hemodynamics.

“We were solving mysteries, running tests to try to understand the cause of a patient’s symptoms,” she says. “It felt like I was back in the basic science lab.”

At that time, Dr. Press was part of an MD/PhD program and had been doing basic science research in hypoxia and oxidative stress. She’d always loved being in the lab, working with her hands and unraveling complex questions.

She realized interventional cardiology combined what she loved about research with patient care, particularly intervening in life-threatening situations.

“I felt that the cardiac patients were the sickest in the hospital, and I saw cardiologists going in there and making a difference. I thought it was really exciting.”

Dr. Press advises students interested in pursuing cardiology to find strong mentors and to follow their hearts.

“If you find something you love and you know you want to do, commit to it.”

She tells her mentees to do what they love because any field in medicine will be challenging. Each specialty has its challenges: a lot of work, hours, and/or stress.

“As long as you do what you love, you can be happy in a stressful job. There will be times when you have to wake up in the middle of the night and you’ll be tired, but you’ll still get through because it’s what you want to do and because you know you are making a difference in someone’s life,” she says.


Learn more about cardiovascular research at UCLA: 

Cardiovascular Research Theme

Cardiovascular Research Laboratory



FAQ for Future Cardiologists

How Much Do Cardiologists Make?

According to the United States Bureau of Labor Statistics, the average annual cardiologist salary in the U.S. is $353,970. 

What Characteristics Make Someone a Good Cardiologist?

Dr. Press says aspiring cardiologists should possess strong stress-management skills.

“When things get hectic, you have to be able to pull back and stay laser focused.”

Practitioners must learn everything about cardiology and also recall knowledge quickly during stressful, often emergency, situations.

How Stressful is Cardiology?

Practicing cardiology is stressful because patient interactions often carry life-or-death consequences.

“Every time I see a patient having a heart attack, my heart rate goes up, I can feel it. I feel the stress and the urgency,” says Dr. Press. “So it’s stressful, but when you’re well trained and when you gain experience, you get better at keeping calm and collected. You know you will get through this situation and make an incredible impact on the patient.”

What Separates Cardiology from Other Specialties?

“One amazing thing about cardiology is that it's always at the cutting edge of research,” says Dr. Press.

Between patient trials and technological innovation, new developments happen frequently in cardiology.

“We used to do open-heart surgery for everything,” Dr. Press explains. “Today, we can treat many things without surgery. Some patients can go home the same day they have a valve replacement.”

About American Heart Month

American Heart Month takes place in February. This national commemoration spreads awareness about heart disease, the number one cause of death in the United States.

During February, organizations such as the American Heart Association, the National Institutes of Health, the White House, and the Centers for Disease Control and Prevention produce media campaigns and outreach toolkits that highlight statistics and tips related to heart health.