Heart- lung interactions: chronic obstructive pulmonary disease and ischemic heart disease

The interaction between the lung and the heart is a vast, complex, and fascinating topic and, from a clinical point of view, disorders of the one often influence and promote disorders of the other. This is especially true for chronic diseases, with chronic obstructive pulmonary disease ( COPD) and ischemic heart disease (IHD) representing a classic example. Epidemiologic data indicate that cardiovascular diseases are frequent in patients with COPD, and vice versa. Accordingly, rates of IHD in COPD vary from 4% up to 60%, while, on the other hand, COPD has been reported in up to 30% of patients with coronary artery disease. Interestingly, prevalence rates are generally significantly higher compared to control populations. COPD and IHD share common risk factors, such as cigarette smoking, physical inactivity, unhealthy lifestyle, and advancing age, which may justify this epidemiologic link. However, other mechanisms such as altered systemic inflammatory response and negative effects of acidosis and hypoxia are probably involved in the correlation between COPD and IHD. Clinically, certain symptoms such as worsening dyspnea, chest tightness, reduced physical activity, and low exercise tolerance are common to both lung and cardiac diseases, and their interpretation may be challenging in clinical practice. However, the identification of COPD in patients with known IHD, and vice versa, is very important, due to higher risk of worse outcomes, lower quality of life, higher hospitalization and, ultimately, higher mortality. Similarly, therapeutic management may be challenging, due to apparently contrasting indications, such as the use of beta-blockers in IHD, and beta2-agonists in COPD, and possible cardiac side effects of bronchodilators. In this narrative review we will discuss these topics, providing a comprehensive evaluation of these two relevant comorbidities.