Cor pulmonale is a common complication of pulmonary hypertension. Its etiology, natural history, clinical features, diagnosis, treatment, and outcomes are reviewed here. The etiology, classification, pathogenesis, clinical manifestations, diagnosis, and treatment of pulmonary hypertension are discussed separately. (See "Overview of pulmonary hypertension in adults" and "Clinical features and diagnosis of pulmonary hypertension in adults" and "Pathogenesis of pulmonary hypertension" and "Treatment of pulmonary hypertension in adults".)
Cor pulmonale refers to the altered structure (eg, hypertrophy or dilatation) and/or impaired function of the right ventricle that results from pulmonary hypertension that is associated with diseases of the lung (eg, chronic obstructive pulmonary disease), vasculature (eg, idiopathic pulmonary arterial hypertension), upper airway (eg, obstructive sleep apnea), or chest wall (eg, kyphoscoliosis). Right-sided heart disease due to left-sided heart disease or congenital heart disease is NOT considered cor pulmonale [1-3].
It is important to note that there are conflicting opinions about the precise definition of cor pulmonale. According to some resources, altered structure and/or function of the right ventricle due to pulmonary vascular disease is not considered cor pulmonale. In other words, the resources only consider right ventricle abnormality due to lung disease, impaired ventilation, or environmental hypoxia to be cor pulmonale. We elected to use the definition that includes pulmonary vascular disease as a cause of cor pulmonale in this review because we felt that this would provide a broader overview of the diagnosis and treatment of such right ventricular disease.
The World Health Organization classifies patients with pulmonary hypertension into five groups based upon etiology . Patients in the first group (Group 1) are considered to have pulmonary arterial hypertension (PAH), while patients in the remaining four groups are considered to have pulmonary hypertension (PH). Cor pulmonale may be associated with any of the etiologies that cause Group 1 PAH (other than left-to-right shunt), Group 3 PH, Group 4 PH, or Group 5 PH (table 1). The most common causes of cor pulmonale are highlighted in this section.
- Chronic obstructive pulmonary disease (COPD) is the most common cause of cor pulmonale in North America [1,2]. It has been estimated that as many as 20 to 30 percent of patients with COPD have cor pulmonale . The severity of cor pulmonale appears to correlate with the magnitude of hypoxemia, hypercapnia, and airflow obstruction, as suggested by a study that found right ventricular hypertrophy in 40 percent of patients with an FEV1 <1.0L and 70 percent of patients with an FEV1 <0.6L . In most patients with COPD, cor pulmonale tends to be accompanied by mild pulmonary hypertension (ie, mean pulmonary artery pressure ≤40 mmHg).
- Interstitial lung diseases (ILD) produce fibrotic destruction of the lung parenchyma and obliteration of the pulmonary vascular bed, leading to pulmonary hypertension and cor pulmonale . The prevalence of cor pulmonale has been best studied among patients with idiopathic pulmonary fibrosis (IPF). Up to 40 percent of patients with IPF have echocardiographic evidence of pulmonary hypertension and many probably also have cor pulmonale . The prevalence increases to 60 percent among those who are awaiting lung transplantation. The prevalence of cor pulmonale may vary according to the type of ILD. (See "Pulmonary hypertension associated with interstitial lung disease".)
- Any pulmonary vascular disorder associated with pulmonary hypertension (eg, idiopathic pulmonary arterial hypertension, scleroderma-related pulmonary arterial hypertension, thromboembolic disease) may be associated with cor pulmonale. These disorders are described separately. (See "Overview of pulmonary hypertension in adults", section on 'Etiologies'.)
- Sleep-related breathing disorders (eg, obstructive sleep apnea, OSA) are associated with pulmonary hypertension and cor pulmonale in about 20 percent of patients . The severity of the accompanying pulmonary hypertension is generally mild and appears to be incompletely related to the severity of the nocturnal respiratory events. Coexisting daytime hypoxemia (eg, chronic lung disease, chronic thromboembolic disease, diastolic heart failure) is usually necessary for pulmonary hypertension and cor pulmonale to develop in patients with sleep-related breathing disorders [2,6,7]. (See "Cardiovascular effects of obstructive sleep apnea", section on 'Pulmonary hypertension'.)