ABSTRACT: Careful monitoring of disease progression is vital to ensuring that patients with pulmonary arterial hypertension receive maximal therapy before the onset of overt right-sided heart failure. Routine follow-up includes the evaluation of symptoms, functional class, and exercise capacity and assessment of pulmonary pressures and right ventricular (RV) function. Transthoracic echocardiography (TTE) offers a noninvasive and fairly reliable technique for monitoring pulmonary artery pressure (PAP) and structural changes of the right side of the heart. However, TTE does not reliably assess cardiac output, right-sided filling pressures, or pulmonary venous pressure. Pulmonary artery catheterization may be particularly useful in patients who have inconsistent findings, such as a reduction in PAP measured by TTE in the presence of worsening symptoms or other signs of disease progression. An increase in RV end-diastolic pressure, usually above 10 mm Hg, is a concern and warrants consideration of additional therapy even if other hemodynamic and clinical parameters are unchanged.
Pulmonary arterial hypertension (PAH) is a disease of the pulmonary arterial tree that results in progressive remodeling and obliteration of the small pulmonary arterioles leading to right ventricular (RV) failure and usually death.1 Although the disease may affect anyone, it is more common in women and often affects young, otherwise healthy persons.2
The devastating effects that PAH has on function and survival have led to an intensive research effort during the past 25 years that has provided intriguing insight into numerous cellular and molecular pathways that are important in pulmonary vascular remodeling. One of the greatest accomplishments has been the identification of a single genetic defect that appears to be present in nearly half of all sporadic cases of PAH and in almost three-quarters of familial cases, providing hope that one day a cure for this tragic disease may be found.3-5
In the meantime, therapies have been developed that slow disease progression and improve survival. Several reviews describing the safety and efficacy of available therapies have proposed treatment algorithms that guide drug selection on the basis of patient characteristics and disease severity (Figure 1).6-8 Implicit in these treatment protocols is the idea that patients should be closely monitored for response to therapy and that therapy should become more aggressive if there is evidence of disease progression.
Footnote to figure 1:
a Strength of ACCP recommendation: A, strong; B, moderate; C, weak; E/A, strong based on expert opinion only; E/B, moderate based on expert opinion only; E/C, weak based on expert opinion only.
b In patients in World Health Organization functional class II or III, oral therapy can be started with an endothelin receptor antagonist or a phosphodiesterase inhibitor. Patients in a more advanced functional class may require prostacyclin or combination therapy. Patients who present with or progress to the worst functional class (class IV) should be given intravenous prostacyclin infusion.
c Not in order of preference.
PAH, pulmonary arterial hypertension; IPAH, idiopathic PAH; ACCP, American College of Chest Physicians.
Adapted from Badesch DB et al. Chest. 2007.7
The purpose of this 2-part article is to review the currently available methods for assessing disease severity in patients with PAH and monitoring patient response to therapy. Despite important therapeutic advances, PAH remains an incurable disease and few patients will experience normalization of pulmonary hemodynamics or exercise function. Thus, early identification of disease progression is vital in maximizing patient response to therapy.
