Certain clinical features of cardiac asthma, defined as congestive heart failure (CHF) associated with wheezing, may be useful in distinguishing it from bronchial asthma, particularly in older patients with COPD (1-3).

• Paroxysmal nocturnal dyspnea associated with wheezing
• Presence of rales or crackles, ascites or other signs of CHF
• Poor response to bronchodilators and corticosteroids
• Formal pulmonary function test with bronchoprovocation demonstrating minimal methacholine response.

Cardiac asthma is not uncommon. In a prospective study of patients 65 yrs of age or older (mean age 82 yrs) presenting with dyspnea due to CHF, cardiac asthma was diagnosed in 35% of subjects. Even in non-elderly patients, cardiac asthma has been reported in 10-15% of patients with CHF (2).

The mechanism(s) underlying cardiac asthma is likely multifactorial. Pulmonary edema and pulmonary vascular congestion have traditionally been considered as key factors either through edema in the interstitial fluid of bronchi squeezing the bronchiolar lumen or by externally compressing the entire airway structure and the bronchiole wall. Reflex bronchoconstriction involving the vagus nerve, bronchial hyperreactivity, systemic inflammation, and airway remodeling may also play a role (1,3). 

Treatment of choice for cardiac asthma typically includes diuretics, nitrates and morphine, not bronchodilators or corticosteroids (1,3). 

Bonus Pearl: Did you know that the term “cardiac asthma” was first coined by the Scottish physician, James Hope, way back in 1832 to distinguish it from bronchial asthma!

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References
1. Litzinger MHJ, Aluen JKN, Cereceres R, et al. Cardiac asthma: not your typical asthma. US Pharm. 2013;38:HS-12-HS-18. https://www.uspharmacist.com/article/cardiac-asthma-not-your-typical-asthma
2. Jorge S, Becquemin MH, Delerme S, et al. Cardiac asthma in elderly patients: incidence, clinical presentation and outcome. BMC Cardiovascular Disorders 2007;7:16. https://www.ncbi.nlm.nih.gov/pubmed/17498318
3. Tanabe T, Rozycki HJ, Kanoh S, et al. Cardiac asthma: new insights into an old disease. Expert Rev Respir Med 2012;6(6), 00-00. https://www.ncbi.nlm.nih.gov/pubmed/23234454