What Does a Cardiologist Do

Cardiologists are physicians who specialize in diagnosing, treating, and managing diseases of the heart and blood vessels. The scope of the specialty extends from preventive risk reduction to the management of acute heart attacks, complex arrhythmias, and advanced heart failure. Understanding what cardiologists do — and what falls outside their scope — helps patients navigate referrals, procedures, and long-term care with greater clarity. The Cardiology Authority home covers the full landscape of this specialty.

Definition and Scope

A cardiologist holds a medical degree (MD or DO) followed by an internal medicine residency of 3 years and a cardiovascular disease fellowship of at least 3 additional years, as defined by the Accreditation Council for Graduate Medical Education (ACGME). Board certification is granted by the American Board of Internal Medicine (ABIM) through its Cardiovascular Disease certification pathway, which requires passing a written examination after completing accredited training (ABIM Cardiovascular Disease Certification).

The specialty's scope, as defined by the American College of Cardiology (ACC), spans six core domains:

  1. Prevention and risk factor management — lipid disorders, hypertension, diabetes-related cardiac risk, and smoking cessation counseling
  2. Diagnostic evaluation — electrocardiography, echocardiography, nuclear imaging, cardiac MRI, and stress testing
  3. Coronary artery disease management — acute and chronic presentations, including post-myocardial infarction care
  4. Arrhythmia diagnosis and medical management — atrial fibrillation, ventricular tachycardia, heart block
  5. Heart failure management — guideline-directed medical therapy, device evaluation, and transplant referral coordination
  6. Structural and valvular heart disease — evaluation of valve disorders, congenital defects in adults, and cardiomyopathies

The regulatory context for cardiology details how federal agencies including the Centers for Medicare & Medicaid Services (CMS) and the Food and Drug Administration (FDA) govern the devices, drugs, and imaging procedures cardiologists use.

How It Works

A standard cardiology encounter follows a structured clinical process. Initial evaluation involves history-taking focused on cardiac symptoms — chest pain, dyspnea, palpitations, syncope — followed by physical examination including auscultation, blood pressure measurement, and assessment of peripheral pulses.

Diagnostic workup proceeds in phases:

  1. First-line testing — a 12-lead electrocardiogram (EKG) is typically the first instrument deployed; it identifies rhythm abnormalities, conduction defects, and evidence of prior infarction within minutes
  2. Imaging — echocardiography uses ultrasound to quantify ejection fraction, wall motion, and valve function; a normal left ventricular ejection fraction (LVEF) falls between 52% and 72% in men and 54% and 74% in women (American Society of Echocardiography, 2015 guidelines)
  3. Functional assessment — cardiac stress testing evaluates exercise capacity and detects inducible ischemia
  4. Advanced imaging — cardiac MRI and CT coronary angiography are deployed when anatomy or tissue characterization requires higher resolution
  5. Invasive evaluation — cardiac catheterization and angiography remains the definitive modality for coronary anatomy assessment and hemodynamic measurement

Treatment decisions are guided by ACC/American Heart Association (AHA) clinical practice guidelines, which assign evidence grades (A, B, C) and recommendation classes (I, IIa, IIb, III) to specific interventions. Pharmacologic therapy, procedural intervention, and device implantation each require distinct informed consent processes governed by institutional review standards and CMS Conditions of Participation (42 CFR Part 482).

Common Scenarios

Cardiologists encounter a predictable distribution of clinical presentations. Coronary artery disease (CAD) and hypertension represent the two highest-volume diagnoses in outpatient cardiology practices. Heart failure accounts for more than 1 million hospitalizations annually in the United States (CDC, Heart Failure Fact Sheet). Atrial fibrillation and other arrhythmias represent the most common sustained cardiac rhythm disorder, affecting an estimated 2.7 to 6.1 million Americans (CDC, Atrial Fibrillation).

Acute presentations seen in inpatient and emergency settings include:

Chronic outpatient management involves:

Decision Boundaries

Cardiologists diagnose and manage cardiovascular disease medically and procedurally, but their scope has defined limits distinguishing the specialty from adjacent fields.

Cardiology vs. Cardiac Surgery: Cardiologists do not perform open-chest surgery. Procedures such as coronary artery bypass surgery and open heart valve repair and replacement fall within the domain of cardiac surgery. The boundary between the two specialties is addressed directly in the cardiology vs. cardiac surgery reference, which outlines how the two fields overlap in hybrid procedures and multidisciplinary heart team decisions.

Interventional vs. Non-Interventional Cardiology: Not all cardiologists perform catheter-based procedures. Interventional cardiologists complete an additional 1-year fellowship (ACGME Interventional Cardiology Program Requirements) and hold separate board certification through the ABIM. General cardiologists refer patients for procedures such as transcatheter aortic valve replacement (TAVR) rather than performing them.

Electrophysiology: Arrhythmia management beyond medication — including cardiac ablation, implantable cardioverter-defibrillator (ICD) implantation, and device programming — requires electrophysiology subspecialty training. The electrophysiology fellowship page outlines the additional 1-to-2-year training pathway.

Pediatric vs. Adult Congenital Cardiology: Adult cardiologists manage congenital heart defects in adults through subspecialty expertise in adult congenital heart disease (ACHD), which is a separately credentialed ABIM subspecialty. Pediatric congenital disease falls to pediatric cardiologists, a distinct training pathway outside adult internal medicine.

The subspecialties of cardiology page provides a structured breakdown of all recognized cardiology subspecialties and their respective ACGME and ABIM certification requirements.

References

The law belongs to the people. Georgia v. Public.Resource.Org, 590 U.S. (2020)