From the Guidelines
Cardiac asthma is a condition that should be managed by addressing the underlying heart failure, with treatment focusing on reducing fluid overload and improving heart function, rather than using traditional asthma medications, as evidenced by the 2015 study 1.
Key Characteristics of Cardiac Asthma
- Cardiac asthma is characterized by wheezing and shortness of breath that resembles bronchial asthma but is actually caused by heart failure rather than primary lung disease.
- It occurs when fluid backs up into the lungs (pulmonary edema) due to the heart's inability to pump efficiently, typically from left-sided heart failure.
- The condition can be diagnosed by the presence of new or worsening symptoms of heart failure, such as dyspnea, decreased exercise tolerance, fatigue, and worsened end-organ perfusion, as outlined in the 2015 study 1.
Treatment of Cardiac Asthma
- Diuretics like furosemide (40-80mg IV or oral) are first-line treatments to reduce fluid overload, as they help to remove excess fluid from the body and alleviate pulmonary congestion.
- ACE inhibitors such as lisinopril (starting at 2.5-5mg daily) or beta-blockers like metoprolol (starting at 12.5-25mg twice daily) may be prescribed to improve heart function and reduce the workload on the heart.
- Supplemental oxygen should be provided to maintain oxygen saturation above 92%, as hypoxemia can worsen the condition and lead to further complications.
- In acute episodes, morphine (2-4mg IV) may help reduce anxiety and preload, thereby alleviating some of the symptoms of cardiac asthma.
Importance of Distinguishing Cardiac Asthma from Bronchial Asthma
- The distinction between cardiac asthma and bronchial asthma is crucial because bronchodilators and steroids used for bronchial asthma are generally ineffective for cardiac asthma, while heart failure medications address the root cause by improving cardiac function and reducing pulmonary congestion.
- A study from 2016 2 highlights the importance of considering cardiac causes of dyspnea, particularly in patients with exercise-induced bronchoconstriction, and recommends referral to specialists such as cardiologists or pulmonologists for further evaluation.
- By prioritizing the treatment of the underlying heart failure, patients with cardiac asthma can experience significant improvements in their symptoms and quality of life, as well as reductions in morbidity and mortality.
From the Research
Definition and Clinical Presentation of Cardiac Asthma
- Cardiac asthma is defined as wheezing, coughing, and orthopnea due to congestive heart failure 3
- The clinical distinction between bronchial asthma and cardiac asthma can be straightforward, except in patients with chronic lung disease coexisting with left heart disease 3
- Cardiac asthma patients often have a poor response to diuretics, and classical asthma medications like bronchodilators or corticosteroids have limited effectiveness in treating cardiac asthma 3
Pathophysiology and Treatment of Cardiac Asthma
- Pulmonary edema and pulmonary vascular congestion are thought to be the primary causes of cardiac asthma, but circulating inflammatory factors and tissue growth factors also lead to airway obstruction 3
- Early administration of furosemide has been associated with improved oxygenation in patients with acute heart failure 4
- Continuous intravenous furosemide infusion can be a simple and effective method of delivering diuretic therapy in patients with advanced heart failure 5
Association with Other Conditions and Outcomes
- Cardiovascular disease is often associated with asthma, and asthma patients have an increased risk of cardiovascular disease mortality 6
- Cardiac asthma is common in elderly patients, and patients with cardiac asthma have a higher incidence of tobacco use, chronic obstructive pulmonary disease, and peripheral arterial disease 7
- The in-hospital and one-year mortality rates for cardiac asthma patients are similar to those with classical congestive heart failure 7
Therapeutic Implications
- Understanding the pathogenic pathways shared by asthma and cardiovascular disease is critical to the choice of pharmacological interventions 6
- Inhaled β2-agonists and corticosteroids may have beneficial effects on both asthma and cardiovascular disease, while cardio-selective β1-blockers should be prescribed with caution in asthma patients 6