The following questions can help distinguish cardiovascular from pulmonary or other causes of dyspnea. The history along with physical examination and cardiopulmonary studies will generally determine the underlying cause of excessive shortness of breath. Table 1 summarizes different causes of dyspnea important to consider in athletes, and Table 2 summarizes ancillary studies to consider during the workup of dyspnea.
- 1) Is the shortness of breath recent, or has it been occurring for some time (weeks or months)? Is it consistent and reproducible in its presentation and level of exercise, or is it inconsistent?
Shortness of breath with intense exercise is a normal response, but differentiating between normal exercise-induced shortness of breath and dyspnea associated with a serious heart or lung condition is not always simple (Table 1). A sudden onset, a significant decrease in exercise performance, or an inconsistent presentation may be the first sign of cardiac or pulmonary abnormality and warrants further evaluation.
- 2) Is there associated chest discomfort?
Any athlete with chest pain and dyspnea at a minimum should receive a resting electrocardiogram (ECG), possibly followed by an echocardiogram and a maximal symptom-limited exercise test, provided that the athlete has had no obvious pulmonary or musculoskeletal cause.
- 3) Is there lightheadedness, or has the patient passed out during exercise?
Shortness of breath can be associated with rhythm disturbances during exercise. Any history of lightheadedness or passing out (syncope) should be thoroughly evaluated for the possibility of serious rhythm disturbances. Structural heart diseases associated with these symptoms include congenital aortic stenosis, hypertrophic cardiomyopathy (HCM), or rarely pulmonary hypertension.
- 4) Is there a family history of a serious heart condition or sudden death?
A family history of HCM or arrhythmogenic right ventricular cardiomyopathy strongly raises the likelihood of dyspnea caused by rhythm disturbances, and further investigation based on the details of the family history is indicated (see the family history section).
- 5) Is there a history of exercise-induced asthma (EIA), or has the individual recently moved to a new environment?
EIA is the most common reason for excessive shortness of breath in an otherwise healthy athlete.
- 6) Is the athlete underperforming during competition and/or experiencing excessive fatigue during regular activities?
Overtraining syndrome (OTS) should be suspected in an athlete who is undergoing heavy training or competition, and cardiovascular causes and other medical illnesses have been ruled out. OTS may be associated with chronic tiredness, unusual fatigue, or shortness of breath with normal athletic competition, underperformance, and difficulty sleeping. Loss of appetite, weight loss, heavy painful muscles, and excessive sweating may be reported.
A cardiopulmonary exercise test can help differentiate between a cardiac and pulmonary cause of excessive shortness of breath with exercise. A cardiac cause should be suspected if the breathing reserve (maximal voluntary ventilation at rest divided by maximal ventilation with exercise) is normal (20% to 40%). Undiagnosed exercise-related asthma can be induced with exercise stress testing that includes the respiratory components.
Case 1: Dyspnea Associated with a Presyncopal Episode in a Young Athlete
A 19-year-old female endurance athlete mentioned on her PPE an episode of dyspnea associated with presyncope while running on a warm day. The athlete had a remote history of chest pain, no palpitations, and no family history of cardiomyopathy or sudden death. Physical examination results were unrevealing. ECG and echocardiogram results were both normal. The athlete was cleared to restart training, and the episode was considered to be neurocardiogenic in origin.
Key Point: All athletes with dyspnea and syncope/presyncope should receive a workup that includes an ECG and resting echocardiogram. Abnormal cardiac remodeling should lead to further evaluation. In athletes, the echocardiogram protocol should include a basal short axis view to visualize the origin of the coronary arteries.
Case 2: An Unsuspecting Case of Systemic Illness
A 55-year-old national-level cyclist reported feeling shortness of breath during competition. For the last 5 years, he consistently finished in the top three for his age category, but during the last year, he finished in the mid-teens. After initial consultation, his ECG, echocardiogram, and exercise echocardiogram results were considered normal, and the patient was advised to resume training. During the following year, his performance continued to drop further. A repeat echocardiogram revealed an increase in wall thickness, and an infiltrative cardiac process was suspected. Further investigation confirmed that the patient had multiple myeloma complicated by cardiac amyloidosis.
Key Point: Although a rare case, he highlights the fact that symptoms may be overlooked or underestimated in older athletes.
Case 3: Dyspnea and Pulmonary Hypertension in a Young Athlete
A young 23-year-old female rower reported progressively increasing shortness of breath during the last year with decreased exercise performance. History was unrevealing, and the physical examination result demonstrated increased second heart sound with a mild holosystolic murmur at the parasternal border. The ECG revealed borderline right axis deviation. Because of the history of progressive dyspnea and the finding on physical examination of an increased S2, an echocardiogram was ordered and results revealed a mildly enlarged right ventricle with mild tricuspid regurgitation, an estimated right ventricular systolic pressure of 42 mm Hg, and normal left ventricle size. Magnetic resonance imaging (MRI) did not show fatty infiltration. Right heart catheterization confirmed the presence of pulmonary arterial hypertension.
Key Point: Pulmonary hypertension is a rare cause of dyspnea in athletes but should be considered. An MRI should be obtained in patients with evidence of disproportionate right heart enlargement, especially in nonendurance sports.