Shortness of Breath: When to Worry It's Your Heart
Shortness of breath is one of the most common reasons people end up in a cardiology office, and it's also one of the most ambiguous. The lungs and the heart are separated by a few inches of mediastinum, they share blood, they share nerve supply, and they share a final common pathway in how they make a person feel. A patient who tells me they're winded climbing stairs could be describing heart failure, valvular disease, COPD, asthma, deconditioning, anemia, anxiety, or pulmonary embolism. Untangling which one (or which combination) is the work of the visit.
I'm Dr. Damian Rasch, a cardiologist in Encinitas. This article walks through how I think about new shortness of breath in clinic, what the cardiac causes look like, what the dangerous mimickers look like, what the workup is, and when to escalate to urgent care versus an ER versus a 911 call. The goal is to give you a framework so you can decide where on the urgency spectrum your symptoms sit and what to do next.
What Cardiac Shortness of Breath Feels Like
When the heart is the cause of shortness of breath, the underlying problem is almost always elevated pressure in the pulmonary capillaries. The left side of the heart, for one of several possible reasons, isn't draining blood out of the lungs as efficiently as it should. Pressure backs up. Fluid begins to leak into the lung interstitium and eventually into the alveoli themselves. The lungs get heavier and stiffer, gas exchange suffers, and the brain registers that breathing isn't keeping up with the body's needs. The patient feels short of breath.
That mechanism produces a recognizable set of symptoms. The first and most reliable is exertional dyspnea: shortness of breath that comes on with activity and improves with rest. In early heart failure, the patient gets winded climbing one flight of stairs that they used to take without thinking. In more advanced disease, the threshold drops. They get winded walking on flat ground, then walking across the room, then talking on the phone. The progression can be slow over months or fast over days.
Most patients with cardiac shortness of breath also develop orthopnea, which is shortness of breath that gets worse when lying flat and improves when sitting up. The pillow count is the bedside test: how many pillows do you sleep on, and has that changed? A patient who used to sleep on one pillow and now needs two or three is telling me something. A patient who can't sleep flat at all and has migrated to a recliner has advanced congestion that warrants urgent evaluation.
A subset of patients develops paroxysmal nocturnal dyspnea (PND), which is sudden severe shortness of breath an hour or two after lying down that wakes them from sleep. They sit up urgently, sometimes get out of bed, and recovery takes ten to thirty minutes. PND is one of the more specific symptoms in heart failure, and a true PND episode shifts the diagnostic probability sharply.
A position-dependent night cough often accompanies the same physiology, sometimes with frothy or pink-tinged sputum in more severe pulmonary edema. Some patients also describe a sense of breathing through a wet sponge, or a tightness across the chest that improves with sitting upright.
The constellation of exertional dyspnea, orthopnea, PND, leg swelling, and recent weight gain is the classic picture of heart failure decompensation. Any one of those symptoms in isolation has a long differential. All five of them together in the same patient over a few weeks is heart failure until proven otherwise.
The Cardiac Causes Worth Knowing
Cardiac shortness of breath is a syndrome with many possible mechanisms, and the workup is partly about figuring out which mechanism is in play because that determines the treatment.
Heart failure with reduced ejection fraction (HFrEF) is the classic pump failure pattern. The left ventricle can't squeeze efficiently, ejection fraction drops below 40 percent, and the heart can't keep up with venous return. Causes include prior myocardial infarction (the most common cause in the United States), longstanding hypertension, viral or idiopathic dilated cardiomyopathy, valvular disease that has progressed to the point of impairing pump function, and various toxic or infiltrative cardiomyopathies. The treatment paradigm has changed dramatically in the last decade. The four-pillar regimen (a beta-blocker, an ACE inhibitor or ARB or sacubitril/valsartan, an MRA like spironolactone, and an SGLT2 inhibitor like dapagliflozin or empagliflozin) extends life and improves how patients feel.
Heart failure with preserved ejection fraction (HFpEF) is increasingly common, especially in older patients with hypertension, diabetes, obesity, and chronic kidney disease. The ventricle squeezes adequately but is stiff and can't relax to accept incoming blood. The result is the same: pulmonary congestion, exertional dyspnea, orthopnea. HFpEF is harder to diagnose than HFrEF because the echo can look nearly normal, and the diagnosis sometimes requires invasive hemodynamic testing or exercise echo. The treatment was historically frustrating, but the SGLT2 inhibitors have changed the picture, with both empagliflozin and dapagliflozin showing meaningful benefit in HFpEF in recent randomized trials.
Valvular heart disease can cause shortness of breath through several mechanisms. Severe aortic stenosis impairs forward flow and elevates left ventricular pressures, causing exertional dyspnea, angina, and syncope. Severe mitral regurgitation overloads the left atrium and pulmonary venous system. Severe aortic regurgitation overloads the left ventricle. Mitral stenosis (now mostly seen in patients from rheumatic-fever-endemic regions) causes elevated left atrial and pulmonary pressures with relatively preserved left ventricular function. Each valve lesion has its own treatment threshold, and the major recent advance has been transcatheter therapies (TAVR for aortic stenosis, MitraClip for selected mitral regurgitation) that allow valve intervention in patients who are too high-risk for surgery.
Coronary ischemia can cause shortness of breath as an anginal equivalent, especially in women, diabetics, and older patients. Some patients with coronary disease never feel chest pain; they feel exertional dyspnea instead. The diagnostic clue is that the dyspnea comes on with the same level of exertion every time and resolves with rest, much like classic angina. A stress test, coronary CT angiogram, or coronary angiogram is the appropriate workup.
Atrial fibrillation, especially when poorly rate-controlled or new in onset, can cause significant shortness of breath. The loss of atrial kick combined with a fast irregular ventricular response drops cardiac output by 20 to 30 percent in some patients, especially those with HFpEF or stiff ventricles who depend on atrial contraction for filling. New AFib in a patient with worsening dyspnea deserves both rate or rhythm control and a heart failure workup.
Pulmonary hypertension is a less common but important cause. The right ventricle struggles to pump against elevated pulmonary pressures, leading to exertional dyspnea, fatigue, and eventually right heart failure. Causes include chronic left heart disease (the most common), chronic lung disease, chronic thromboembolic disease, and idiopathic pulmonary arterial hypertension. The workup includes echo (with TR jet velocity to estimate pulmonary pressure) and often right heart catheterization.
Pericardial disease, including constrictive pericarditis and large pericardial effusions, can cause shortness of breath. Constrictive pericarditis is uncommon but treatable, and it tends to be missed because the echo can look surprisingly normal. The classic features include elevated jugular venous pressure with prominent X and Y descents, Kussmaul sign, and sometimes a pericardial knock on auscultation.
When the Cause Is Probably Not Cardiac
Several non-cardiac conditions cause shortness of breath, and recognizing them helps focus the workup.
Asthma classically causes episodic wheezing, cough, and chest tightness with triggers like cold air, exercise, allergens, or upper respiratory infections. The symptoms respond to bronchodilators, often dramatically. Spirometry shows reversible airflow obstruction. Adult-onset asthma is increasingly recognized and is sometimes mistaken for cardiac dyspnea, especially in patients with both conditions.
COPD is the result of years of cigarette smoke exposure (most commonly) or other inhaled toxins. It causes progressive exertional dyspnea, chronic cough with sputum production, and recurrent exacerbations. Spirometry shows fixed airflow obstruction with FEV1/FVC below 0.7. Patients with COPD often have coexisting heart disease, and untangling which problem is contributing to which symptom requires careful evaluation.
Interstitial lung disease, including idiopathic pulmonary fibrosis, sarcoidosis, and connective tissue disease–associated lung disease, causes progressive exertional dyspnea, dry cough, and a characteristic dry "Velcro" crackle on lung exam. High-resolution CT of the chest is the workup. Pulmonary function tests show a restrictive pattern with reduced DLCO.
Anemia reduces oxygen-carrying capacity and can cause exertional dyspnea, fatigue, and palpitations. A simple CBC is usually all it takes to identify it, and the workup pivots to finding the cause (iron deficiency, B12 deficiency, hemolysis, chronic disease, malignancy).
Deconditioning is the most common cause of new exertional dyspnea in patients who haven't exercised in months or years. The cure is gradual progressive activity, ideally with cardiac and pulmonary screening to rule out coexisting disease before starting.
Anxiety and panic disorder can cause sudden episodes of shortness of breath, often with chest tightness, palpitations, sweating, and a sense of impending doom. The episodes typically last 10 to 30 minutes and resolve spontaneously. A baseline cardiac and pulmonary workup is appropriate, especially when risk factors are present, but once a baseline is reassuring the focus shifts to anxiety management.
Obesity hypoventilation syndrome and obstructive sleep apnea cause exertional dyspnea, fatigue, and daytime sleepiness. Sleep apnea is an important comorbidity in cardiac patients because it worsens hypertension, atrial fibrillation, and right heart strain. A sleep study is appropriate when the history is suggestive.
The Dangerous Mimickers
A few causes of shortness of breath are emergencies and need to be on the differential whenever a patient presents acutely.
Pulmonary embolism is the dangerous mimicker most often missed. PE classically causes sudden shortness of breath, sometimes with sharp chest pain that worsens with breathing, sometimes with cough or hemoptysis, sometimes with leg swelling on one side from a deep venous thrombosis. Massive PE can cause hypotension, syncope, and cardiac arrest. Risk factors include recent surgery (especially orthopedic), prolonged immobility, cancer, hormone therapy or oral contraceptives, pregnancy and postpartum, prior DVT or PE, and inherited thrombophilias. The diagnostic test is usually a CT pulmonary angiogram. Treatment ranges from anticoagulation alone to systemic thrombolysis or catheter-directed therapy depending on severity.
Acute pulmonary edema from cardiac decompensation can come on in hours. The patient is severely short of breath at rest, often coughing pink frothy sputum, often unable to lie down at all, often diaphoretic and pale. Triggers include acute MI, hypertensive emergency, severe valvular disease (especially acute mitral regurgitation from a ruptured chord or papillary muscle), and arrhythmias. Treatment involves oxygen, IV diuretics, vasodilators, sometimes noninvasive positive-pressure ventilation, and often admission to the cardiac unit.
Tension pneumothorax is a collapsed lung that has progressed to the point of mediastinal shift and impaired venous return. Severe sudden shortness of breath, hypotension, and absent breath sounds on one side. Treatment is needle decompression followed by chest tube placement.
Anaphylaxis causes sudden shortness of breath with wheezing, often with hives, swelling of the face or lips, hypotension, and a known allergen exposure. Treatment is intramuscular epinephrine, given immediately, before any other intervention.
Cardiac tamponade from a rapidly accumulating pericardial effusion causes shortness of breath, hypotension, distant heart sounds, and pulsus paradoxus. Causes include malignancy, trauma, postoperative bleeding, aortic dissection rupturing into the pericardium, and viral pericarditis. Treatment is urgent pericardiocentesis.
When to Call 911 Versus Schedule a Visit
The single most useful question to answer for any patient with new shortness of breath is: how urgent is this? The answer depends on the severity, the speed of onset, and the associated symptoms.
Call 911 immediately if you have severe shortness of breath at rest, especially if it came on suddenly, if it's accompanied by chest pain, if you're coughing pink or frothy sputum, if you can't speak in full sentences without pausing for breath, if your lips or fingernails are turning blue, if you feel faint, or if you have known coronary disease or heart failure with a sudden change from your baseline. The reason to call rather than drive is that paramedics can give oxygen, assess your rhythm, and start treatment in the ambulance, and the receiving ER can be ready when you arrive.
Go to an emergency department or urgent care promptly (within hours) if you have new moderate shortness of breath, if you have new wheezing without an obvious asthma trigger, if you have shortness of breath with leg swelling that's new on one side (worry about DVT/PE), if you have shortness of breath with palpitations, or if you have a recent diagnosis of cancer or recent surgery and develop new shortness of breath (PE risk).
Schedule a primary care or cardiology visit within days for new exertional dyspnea that's gradual in onset, for orthopnea that's slowly progressive, for fatigue with mild exertional dyspnea, for new-onset wheezing in a patient with known asthma, or for shortness of breath that comes on only with significant exertion. The clinic visit is the right setting when the symptoms are new but stable and the patient is comfortable at rest.
When in doubt, err toward urgency. Acute pulmonary edema and pulmonary embolism are time-sensitive, and patients who delay coming in for severe shortness of breath sometimes pay for that delay.
The Workup
In clinic, the workup for new shortness of breath is well-established and usually doesn't take long once the patient has been seen.
The history is usually the most important part. I want to know how long the symptoms have been present, what brought them on, what makes them better or worse, what associated symptoms are present (chest pain, palpitations, leg swelling, weight gain, cough, fevers), what the patient's risk factors are, and what their baseline functional capacity used to be. A patient who used to walk three miles a day and now gets winded going to the mailbox is telling me something specific about how the trajectory has changed.
The exam includes vital signs (looking especially at oxygen saturation and resting heart rate), a careful cardiovascular exam (listening for murmurs, gallops, rubs, jugular venous pressure, peripheral edema), and a careful pulmonary exam (listening for crackles, wheezing, decreased breath sounds, signs of consolidation).
The first lab I order is usually a BNP or NT-proBNP. These biomarkers are released by the heart when it's stretched and correlate well with elevated cardiac filling pressures. NT-proBNP cutoffs are age-stratified: above 450 pg/mL is suggestive of heart failure under age 50, above 900 between 50 and 75, and above 1800 over 75. BNP above 100 pg/mL is suggestive, above 500 highly specific. Normal BNP makes heart failure unlikely as the cause of dyspnea, with caveats: BNP can be artifactually low in obesity and in well-compensated chronic HFpEF.
A CBC screens for anemia and elevated white count. A basic metabolic panel screens for renal dysfunction and electrolyte abnormalities. A D-dimer is sometimes added when PE is on the differential, with the caveat that D-dimer is sensitive but not specific.
An EKG screens for ischemia, prior MI, atrial fibrillation, conduction abnormalities, and right ventricular strain (which can be a clue to PE). A chest X-ray looks for pulmonary congestion, cardiomegaly, pneumonia, pleural effusions, and pneumothorax.
An echocardiogram is the single most useful test in evaluating cardiac dyspnea. It measures left and right ventricular function, looks for valvular disease, estimates pulmonary pressure, assesses for pericardial effusion, and gives an overall picture of cardiac structure and function. In most patients with new shortness of breath, an echo is the test that anchors the diagnosis.
If sleep apnea is suspected, a sleep study is appropriate. If COPD or asthma is suspected, pulmonary function tests are next. If PE is suspected, a CT pulmonary angiogram is the test of choice. If interstitial lung disease is on the differential, a high-resolution CT of the chest is useful.
For patients with HFpEF physiology that's hard to confirm on echo, an exercise echocardiogram or right heart catheterization with exercise can demonstrate elevated filling pressures during exertion that aren't apparent at rest.
Common Patient Questions
I'm 65 and I get winded climbing stairs now. Is that heart failure or just aging?
It depends on the pattern. Some decline in exertional capacity is normal with age, and a healthy 65-year-old shouldn't get severely winded climbing one or two flights, but might notice a difference compared to age 35. The question is whether the change has been gradual over years (more likely deconditioning or normal aging) or rapid over weeks to months (more concerning). New exertional dyspnea that's progressed quickly, or that's accompanied by other heart-related symptoms (orthopnea, leg swelling, weight gain), warrants a workup. Get a BNP, an EKG, and an echo. If they're reassuring, focus on a structured exercise program to rebuild capacity.
I had COVID two years ago and I've never been the same. Could that be cardiac?
Possibly. Post-COVID dyspnea has several mechanisms, including direct cardiac involvement (myocarditis, pericarditis), pulmonary parenchymal damage, microvascular dysfunction, and dysautonomia (often POTS-like). The workup typically includes BNP, echo, EKG, ambulatory rhythm monitoring, pulmonary function tests, and orthostatic vital signs. Cardiac MRI is sometimes added to look for myocarditis. Treatment depends on what's found, but many patients with post-COVID dyspnea improve gradually over months to years with structured rehab and treatment of any specific findings.
My BNP is normal but I still feel short of breath. What now?
Normal BNP makes cardiac dyspnea less likely but doesn't rule it out, especially in obese patients or in well-compensated chronic HFpEF. The workup pivots toward pulmonary causes (PFTs, chest CT, sleep study), anemia (CBC), deconditioning (cardiopulmonary exercise testing if needed), and anxiety. If clinical suspicion for cardiac dyspnea remains high despite a normal BNP, an exercise echo or right heart catheterization with exercise can reveal elevated filling pressures that only appear with exertion.
I have asthma and now I'm getting more shortness of breath. Could it be both my asthma and my heart?
Yes, and this combination is common, especially in older patients with risk factors for both. The clue is whether the dyspnea responds to bronchodilators (asthma) or to diuretics (heart failure), or whether it requires both. A BNP, an echo, and PFTs together usually sort out which problem is dominant. Cardiac asthma (wheezing from peribronchial fluid in heart failure) can be misdiagnosed as a worsening of bronchial asthma, and the response to inhalers in those patients is disappointing because the underlying problem is fluid, not bronchospasm.
I just flew home from Europe and now I'm short of breath. Should I worry about a clot?
Yes. Long flights are a known risk factor for DVT and PE, and new shortness of breath after a long flight, especially if accompanied by leg swelling, calf pain, chest pain, or fast heart rate, warrants prompt evaluation. Go to the ER. The workup is usually a D-dimer (often combined with a clinical decision rule like Wells score) and, if indicated, a CT pulmonary angiogram. Treatment for confirmed PE is anticoagulation, often with a direct oral anticoagulant for three to six months.
I'm pregnant and I get short of breath. Is that normal?
Some shortness of breath in pregnancy is normal, related to elevated diaphragm position, increased blood volume, and progesterone-driven hyperventilation. But pregnancy is also a hypercoagulable state with elevated PE risk, and pregnancy can unmask peripartum cardiomyopathy in some patients. Severe shortness of breath, shortness of breath with chest pain, sudden shortness of breath with leg swelling, or shortness of breath that's getting worse rather than stable should be evaluated promptly. The workup in pregnancy is similar to non-pregnant patients, with attention to minimizing radiation exposure to the fetus.
My doctor said I have HFpEF. What does that mean for me?
HFpEF means heart failure with preserved ejection fraction. The heart squeezes adequately but is too stiff to relax and fill properly, so pressures back up into the lungs and you feel short of breath, especially with exertion. HFpEF is most common in older patients with hypertension, obesity, diabetes, atrial fibrillation, and chronic kidney disease, and treating those conditions aggressively is part of the treatment. Add an SGLT2 inhibitor (dapagliflozin or empagliflozin) for proven mortality and hospitalization benefit. Diuretics are used for symptom control. Weight loss, blood pressure control, and exercise rehabilitation make a real difference.
I get short of breath only when I'm anxious. Is it really my anxiety?
Probably, but get a baseline cardiac evaluation at least once. Anxiety routinely produces shortness of breath, chest tightness, palpitations, and dizziness, and many patients have learned to recognize their pattern over years. But anxious patients also have heart disease, and missing a cardiac diagnosis in someone with known anxiety is a recurring pattern in second-opinion consultations. An EKG, an echo, and a baseline assessment let you and your therapist treat the anxiety without wondering whether you're missing something.
A Final Note From Me
Shortness of breath is a symptom that demands respect. Most cases turn out to be one of the manageable causes (deconditioning, asthma, anemia, mild HFpEF), but a meaningful fraction are early signs of serious cardiac or pulmonary disease that respond well to treatment when caught early. Patients who get evaluated promptly for new dyspnea routinely do better than patients who wait, both because they get the diagnosis sooner and because they avoid the complications that come from untreated heart failure or undiagnosed PE.
If you're noticing new exertional dyspnea, a change in the number of pillows you sleep on, a cough that comes on when you lie down, or unexplained leg swelling, mention it at your next visit. The workup is straightforward and inexpensive, and identifying heart failure early dramatically changes the trajectory. Modern heart failure treatment in 2026 has rewritten the prognosis in this disease, and the window to start treatment opens the moment we recognize what we're looking at.
If your shortness of breath came on suddenly, especially with chest pain or after a long flight or after a recent surgery, don't try to characterize it on your own. Get evaluated urgently. The cost of an ER visit that turns out to be benign is much smaller than the cost of an unrecognized PE.
References
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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.