Athletic Heart Syndrome

Evan D. Perez, MD

Daniel Murphy, MD, FAAFP

Justin M. Wright, MD, CAQSM

BASICS

DESCRIPTION

A benign condition consisting of physiologic adaptations to increased cardiac workload. Primary features include biventricular hypertrophy and bradycardia.
Associated with normal systolic and diastolic function
Characteristics may overlap with pathologic conditions.
Synonym(s): athlete’s heart; physiologic cardiac hypertrophy; exercise-induced cardiac remodeling; exercise-related cardiac remodeling

EPIDEMIOLOGY

These adaptations are common in highly trained athletes.
Cardiac remodeling has been observed in moderately active adults who exercise 3 to 5 hr per week (1).
Mistaken for pathologic conditions

ETIOLOGY AND PATHOPHYSIOLOGY

Changes in cardiac structure vary based on type of exercise (2).
Cardiac dimensions rarely exceed upper limits of normal.
Dynamic exercise (e.g., distance running) (2):
- Increased heart rate, augmented stroke volume, and decreased systemic vascular resistance
- Adaptive responses due to volume overload and increased systolic blood pressure (BP)
- Increase left ventricular (LV) end-diastolic diameter with proportional increases in septal and free-wall thickness
Static exercise (e.g., weight lifting, bodybuilding) (2):
- Increased peripheral resistance with smaller increases in heart rate and cardiac output
- Increased septal and free-wall thickness without an increase in LV end-diastolic diameter
Combined exercise (e.g., cycling, rowing) (2):
- Extreme volume and pressure load
- Largest increase in LV end-diastolic diameter, septal wall, and free-wall thickness

RISK FACTORS

DIAGNOSIS

HISTORY

Differentiate benign physiologic change from pathologic conditions.
History of chest pain, dizziness, impaired exercise capacity, or syncope with exercise may be suggestive of pathology.
Inquire about heart disease risk factors, including hypertension (HTN), hyperlipidemia, tobacco use, and family history of sudden cardiac death.
History of cardiac murmur should be investigated.

PHYSICAL EXAM

Decreased body fat and increased muscle mass
Bradycardia (sinus bradycardia or bradycardia with 1st- and 2nd-degree blocks)
Grade 1 or 2 midsystolic murmurs (benign functional ejection murmur, which resolves with Valsalva maneuver)
Third and fourth heart sounds are common (benign filling).
BP remains normal.
Point of maximal ventricular impulse displaced lateral to the midclavicular line.