Shortness of Breath: When It's Your Heart

Shortness of breath is one of the most common reasons patients come to my office. The medical word for it is dyspnea, and it can come from the heart, the lungs, the blood, anxiety, or just being out of shape. Telling those apart is the work of the visit. This article is the framework I use to think about it, written for the patient or family member trying to figure out whether to be worried.

I'm Dr. Damian Rasch, a cardiologist in Encinitas. If your shortness of breath is sudden and severe right now, especially if you also have chest pain, you can't catch your breath at rest, your lips or fingers look blue, or you're confused, please stop reading and call 911. Sudden severe dyspnea can be heart failure, a pulmonary embolism, a heart attack, or asthma badly out of control, all of which need immediate care.

What Cardiac Shortness of Breath Looks Like

Cardiac dyspnea has a few recognizable features. It usually comes on with exertion at first. Patients describe needing to stop walking up a single flight of stairs that they used to manage easily, or feeling winded carrying groceries from the car. It often comes with a sense of pressure or tightness rather than just a need to breathe harder. As heart failure progresses, the dyspnea moves from exertion to rest. The classic triad I look for is exertional dyspnea, orthopnea (shortness of breath when lying flat), and paroxysmal nocturnal dyspnea (waking from sleep gasping for air, usually one or two hours after lying down).

Cardiac dyspnea is often accompanied by other heart-related signs: leg swelling that's worse at the end of the day, weight gain over days, fatigue, and reduced exercise tolerance. If you're seeing these together, the diagnosis usually points toward heart failure.

Pulmonary Causes

Lung-driven dyspnea has its own profile. Asthma often comes with audible wheezing, a known history of allergies or triggers, and responds quickly to inhaled bronchodilators. COPD tends to occur in current or former smokers, with a chronic productive cough, prolonged expiration, and gradually worsening exercise tolerance over years. Pneumonia brings fever, productive cough, sometimes pleuritic chest pain, and is usually a few-day illness rather than a chronic pattern.

Pulmonary embolism is the most dangerous pulmonary cause. It typically presents as sudden shortness of breath, sometimes with sharp chest pain that's worse with breathing, and can come with one-sided leg swelling if the clot started in a leg vein. Risk factors include recent surgery, immobility, long flights, cancer, hormone therapy, and pregnancy. PE is a medical emergency and warrants 911 if suspected.

Pulmonary fibrosis and other interstitial lung diseases cause slowly progressive dyspnea over months to years, often with a dry cough.

Other Causes That Get Misread as Cardiac

Anemia reduces the blood's ability to carry oxygen. Dyspnea on exertion with associated fatigue and pallor in someone with low hemoglobin (often from blood loss, iron deficiency, or chronic disease) responds to treating the anemia.

Anxiety and panic can cause real shortness of breath, often with hyperventilation, tingling fingers, lightheadedness, and a sense of doom. The pattern is paroxysmal and tied to triggering thoughts or situations.

Sleep apnea causes daytime fatigue and morning headaches more than overt dyspnea, but obstructive sleep apnea also worsens heart failure and pulmonary hypertension. Anyone with cardiac dyspnea who snores or has witnessed apneas should be screened.

Deconditioning is the most common cause of new dyspnea I see in clinic. Loss of fitness with age or after illness genuinely shortens the breath with mild activity. The fix is graded reconditioning, but only after the heart and lungs are confirmed healthy.

Long COVID has added a new category over the past few years. Persistent dyspnea after COVID can stem from microvascular damage, mild myocarditis, residual lung inflammation, or autonomic dysfunction. Workup includes echo, sometimes cardiac MRI, and pulmonary function testing.

The NYHA Functional Classification

If you have heart failure or are being evaluated for it, you'll hear your doctors use the New York Heart Association (NYHA) functional class. It's a four-point scale that captures how much your symptoms limit you.

Class I: No limitation. Ordinary activity does not cause symptoms.

Class II: Slight limitation. Comfortable at rest, but ordinary activity causes fatigue or shortness of breath.

Class III: Marked limitation. Comfortable at rest, but less than ordinary activity (a short walk on flat ground, getting dressed) causes symptoms.

Class IV: Symptoms at rest. Any physical activity worsens symptoms.

The class matters because it influences medication choices, eligibility for advanced therapies, and the urgency of follow-up.

The Workup

When a patient comes in with new dyspnea, the standard workup includes:

History and exam. Pattern, triggers, associated symptoms, comorbidities, medications, and a careful look at jugular venous pressure, lung sounds (crackles, wheezes), and leg edema.

EKG. Looks for arrhythmia, prior infarction, and signs of left ventricular hypertrophy.

Chest X-ray. Looks for pulmonary edema, infiltrates, pleural effusion, and cardiomegaly.

BNP or NT-proBNP. These are heart-failure biomarkers. NT-proBNP cutoffs for heart failure are age-stratified: above 450 pg/mL under age 50, above 900 between 50 and 75, and above 1800 over 75. BNP above 100 pg/mL is suggestive, above 500 is highly specific. Elevated levels point strongly toward cardiac dyspnea, normal levels make heart failure unlikely.

Echocardiogram. The single most important test for cardiac dyspnea. Measures ejection fraction, wall motion, valves, and chamber sizes. A normal echo largely rules out severe cardiac causes.

CBC and basic chemistries. Anemia, kidney function, electrolytes.

Pulmonary function tests, chest CT, sleep study. Added when pulmonary or sleep-related causes are on the differential.

When to Escalate

Call 911 for dyspnea that is sudden and severe, that occurs at rest, that comes with chest pain or pressure, that comes with new leg swelling, or that has you working hard to breathe even sitting still.

Call your cardiologist (within hours to a day) if you have known heart failure and your symptoms are worsening, your weight has gone up several pounds in a few days, your usual furosemide dose isn't keeping you dry, or your number of pillows at night has increased.

Schedule a clinic visit within the next week or two for new mild exertional dyspnea, dyspnea that has gradually worsened, or dyspnea that's interfering with daily activities you used to do without thought.

Common Patient Questions

My BNP came back at 200. Do I have heart failure?

A BNP of 200 is mildly elevated and warrants an echocardiogram if you haven't had one recently. BNP can rise modestly with age, kidney dysfunction, atrial fibrillation, and pulmonary hypertension even without overt heart failure. The number is one piece of the picture.

My ejection fraction is 55 percent. Why am I still short of breath?

A normal ejection fraction doesn't rule out cardiac dyspnea. Heart failure with preserved ejection fraction (HFpEF) is a major and growing diagnosis, especially in older patients with hypertension, diabetes, or obesity. Diastolic dysfunction (a stiff ventricle), valve disease, pulmonary hypertension, and amyloidosis can all cause symptoms with normal EF.

I get short of breath only when I lie flat. What does that mean?

Orthopnea is highly suggestive of cardiac causes, especially heart failure. Get an echo and BNP. Sleep apnea can also cause some lie-flat dyspnea but the pattern is different (snoring, witnessed apneas, daytime sleepiness).

I cough at night and sometimes wake up short of breath. Is this cardiac?

Possibly. Paroxysmal nocturnal dyspnea (PND) is a classic heart-failure symptom: awakening one to two hours after lying down with severe shortness of breath that improves with sitting up. Nocturnal cough can also be cardiac (cardiac asthma) but is more often GERD, asthma, or postnasal drip. The presence of orthopnea and PND together warrants a cardiac evaluation.

My doctor says my heart and lungs are fine but I still get winded. What now?

Once major causes are excluded, deconditioning is by far the most likely explanation. A graded exercise program (even gentle walking that progressively builds) almost always improves symptoms. Cardiac rehabilitation can be appropriate for patients with prior cardiac events. Sleep apnea screening and an iron panel are worth considering if not already done.

Can long COVID cause shortness of breath months after infection?

Yes. Persistent post-COVID dyspnea is well-described and can persist for months. The workup typically includes echo, sometimes cardiac MRI to look for myocarditis, pulmonary function testing, and evaluation for orthostatic intolerance and POTS, which are also more common after COVID.

I had a normal stress test last year. Is my dyspnea cardiac?

A normal stress test makes obstructive coronary disease unlikely as the cause but doesn't address heart failure with preserved EF, valve disease, or arrhythmia. If your symptoms are new or progressing, a focused cardiac re-evaluation including echo and BNP is reasonable.

A Final Note From Me

Most of the time, new shortness of breath is not your heart. Most of the time, it's deconditioning, anxiety, asthma, allergic rhinitis, or a viral illness. The reason we still take it seriously and work it up is that the small fraction that turns out to be cardiac, especially heart failure, is much easier to treat early than late. The medications we have for heart failure in 2026 (the so-called four pillars: beta-blockers, ACE inhibitors or ARBs or sacubitril/valsartan, mineralocorticoid receptor antagonists, and SGLT2 inhibitors) extend life dramatically and improve symptoms. But they only help if we identify the heart failure in the first place.

If your dyspnea is new, progressing, or interfering with how you live, get evaluated. The workup is straightforward and most patients leave the visit with reassurance.

References

1. Heidenreich, Paul A., Biykem Bozkurt, David Aguilar, et al. "2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure." Circulation 145, no. 18 (2022): e895-e1032.

2. Januzzi, James L., Carlos A. Camargo, Saif Anwaruddin, et al. "The N-Terminal Pro-BNP Investigation of Dyspnea in the Emergency Department (PRIDE) Study." American Journal of Cardiology 95, no. 8 (2005): 948-954.

3. Maisel, Alan S., Padma Krishnaswamy, Richard M. Nowak, et al. "Rapid Measurement of B-Type Natriuretic Peptide in the Emergency Diagnosis of Heart Failure." New England Journal of Medicine 347, no. 3 (2002): 161-167.

4. Wang, Charlie S., J. Mark FitzGerald, Michael Schulzer, Edwin Mak, and Najib T. Ayas. "Does This Dyspneic Patient in the Emergency Department Have Congestive Heart Failure?" JAMA 294, no. 15 (2005): 1944-1956.

5. McEvoy, R. Doug, Nick A. Antic, Emma Heeley, et al. "CPAP for Prevention of Cardiovascular Events in Obstructive Sleep Apnea." New England Journal of Medicine 375, no. 10 (2016): 919-931.

6. Borlaug, Barry A. "Evaluation and Management of Heart Failure With Preserved Ejection Fraction." Nature Reviews Cardiology 17, no. 9 (2020): 559-573.

7. Lang, Roberto M., Luigi P. Badano, Victor Mor-Avi, et al. "Recommendations for Cardiac Chamber Quantification by Echocardiography in Adults: An Update From the ASE and EACVI." Journal of the American Society of Echocardiography 28, no. 1 (2015): 1-39.

8. McDonagh, Theresa A., Marco Metra, Marianna Adamo, et al. "2021 ESC Guidelines for the Diagnosis and Treatment of Acute and Chronic Heart Failure." European Heart Journal 42, no. 36 (2021): 3599-3726.

9. Konstantinides, Stavros V., Guy Meyer, Cecilia Becattini, et al. "2019 ESC Guidelines for the Diagnosis and Management of Acute Pulmonary Embolism." European Heart Journal 41, no. 4 (2020): 543-603.

10. Wiernik, Esther, Quentin V. Le, et al. "Long-Term Cardiovascular Outcomes in Patients with Long COVID." JAMA Cardiology 8, no. 11 (2023): 1041-1050.

Published on damianrasch.com. The above information was composed by Dr. Damian Rasch, drawing on individual insight and bolstered by digital research and writing assistance. The information is for educational purposes only and does not constitute medical advice.