Cardiac asthma is not a form of asthma. It's a type of coughing or wheezing that occurs with left heart failure. Depending on how severe your symptoms are, this wheezing can be a medical emergency.
Heart failure can cause fluid to build up in your lungs (pulmonary edema) and in and around your airways. The latter causes signs and symptoms — such as shortness of breath, coughing and wheezing — that may mimic asthma.
True asthma is a chronic condition caused by inflammation of the airways, which can narrow them, leading to breathing difficulties. True asthma has nothing to do with fluid in the lungs or heart disease.
The distinction is important because treatments for asthma and heart failure are different. Treatments for heart failure can help improve your symptoms for both the heart failure and the cardiac asthma. Overusing treatments for true asthma, such as rescue inhalers, could be dangerous and lead to a worsening of symptoms.