Heart disease is the leading cause of sudden death in cats that are young to middle - aged. (pethealthnetwork.com)
In cats, heartworm can cause feline associated respiratory disease (creating asthma - like symptoms), and heartworm is the second most common cause of sudden death in cats. (positively.com)
Hypertrophic cardiomyopathy is the most common form of heart disease in cats and can cause heart failure, thromboembolism, and occasionally sudden death in cats (see also Cardiomyopathy in cats). (icatcare.org)