Abstract and Introduction
Purpose of Review Pulmonary hypertension is a common complication seen in patients with advanced chronic obstructive pulmonary disease (COPD). Information related to the true prevalence, implications for functional outcomes, pathogenesis, and therapeutic options available has been lacking. The purpose of this review is to summarize some exciting findings from the last several years that address these holes in our knowledge.
Recent Findings Several recent studies have explored the prevalence and the functional implications of pulmonary hypertension for patients with COPD. These highlight the importance of clearly defining pulmonary hypertension that can be quite heterogeneous in this patient population. Furthermore, the concept that pulmonary hypertension in COPD is merely driven by hypoxic vasoconstriction has been called into question by several lines of investigation that suggest a much more complex pathogenesis potentially occurring independently of hypoxemia. Finally, there has been much interest in exploring pulmonary hypertension-specific therapies in patients with COPD, but available data to support their use are limited.
Summary The recent findings summarized here have expanded our knowledge regarding this important comorbidity in patients with advanced COPD. We now know that pulmonary hypertension is common, has clear effects on both morbidity and mortality, and has a complex pathophysiology that we are only beginning to understand.
Chronic obstructive pulmonary disease (COPD) is a heterogeneous, multisystem disease with complexities that extend far beyond airway obstruction.[1–3] The result is significant heterogeneity in the clinical presentation of patients with COPD.[4–6] Although COPD is defined and graded by the forced expiratory volume in 1 s (FEV1), there is consensus that FEV1 alone is inadequate in describing the complexity of the disease.[7,8] It has recently been proposed that identifying and grouping key elements of patients' clinical presentations to define specific phenotypes may allow for improved understanding of the pathophysiology of COPD. Defining these unique patient groups may also enable more targeted therapeutic trials to guide phenotype-specific management. Pulmonary hypertension in patients with COPD is a well recognized comorbidity, potentially defining one of these phenotypes with distinct effects on both patient function and mortality.
Pulmonary hypertension is a hemodynamic diagnosis that requires confirmation by right heart catheterization. Pulmonary hypertension in COPD belongs to WHO group 3 or pulmonary hypertension owing to lung diseases or hypoxemia according to the proceedings of the fourth World Symposium on Pulmonary Hypertension at Dana Point 2008. As opposed to WHO group 1 or pulmonary arterial hypertension that has well defined diagnostic criteria [mean pulmonary artery pressure (mPAP) 25 mmHg with a pulmonary capillary wedge pressure (PCWP) <15mmHg], the hemodynamic definition of pulmonary hypertension related to COPD has been inconsistent in the literature.[11–13,14••,15] The current accepted criterion, mPAP 25 mmHg or more with underlying hypoxic lung disease, fails to capture the complexity of this diagnosis in which vascular remodeling, hypoxia, cardiac comorbidities, and changes in lung mechanics all contribute to elevated pulmonary artery pressures. The inconsistencies in definition, multiple causes for the onset of pulmonary hypertension, and the invasiveness of diagnostic testing have contributed to difficulties identifying its true prevalence.
Curr Opin Pulm Med. 2012;18(2):138-143. © 2012 Lippincott Williams & Wilkins