Prevalence and importance of comorbidities in patients with heart failure.

Heart failure (HF), being a disease of the elderly, is associated with several noncardiac comorbidities, defined as chronic conditions coexisting with HF that play an integral role in its development, progression, and response to treatment. These include pulmonary dysfunction, sleep-disordered breathing, renal dysfunction, liver dysfunction, anaemia, thyroid disorders, diabetes mellitus, skeletal myopathy, depression, and cognitive impairment. The noncardiac comorbidity burden is higher and associated with higher non-HF hospitalizations in patients with HF and preserved, as compared with those with HF and reduced, left-ventricular ejection fraction. Since chronic inflammation is a characteristic feature of both HF and the coexisting morbidities, it may play a pivotal role in their development, progression, and interactions.