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Question

Is pulmonary arterial hypertension common in cases of IPF?

Response from  Steven D. Nathan, MD
Medical Director, Advanced Lung Disease and Transplant Program, Inova Fairfax Hospital, Falls Church, Virginia

Before attempting to answer this question, it is important to be cognizant of nomenclature. Pulmonary arterial hypertension refers to WHO group I etiologies of pulmonary hypertension (PH). Idiopathic pulmonary fibrosis (IPF) is characterized in WHO group III as a cause of PH with other forms of parenchymal lung disease.^[1] There is also the potential for a pun in answering this question. The pathologic correlate of IPF is "usual interstitial pneumonitis," since, when it was first described, this was the most usual pattern of injury seen with the idiopathic interstitial pneumonias. So the short answer to the question can be "yes," but this is predicated by when during the course of the disease it is sought.

The prevalence that we came up with in a retrospective review of right heart catheterization (RHC) data in our IPF patient population was about a third of patients with PH defined by the standard criteria of a mean pulmonary arterial pressure (PAP) > 25 mm Hg.^[2] A higher prevalence of PH of 85% (74/88 patients) was described in an echocardiographic study from the Mayo Clinic where PH was defined by an estimated systolic PAP > 35 mm Hg.^[3] As intimated, the prevalence is likely related to the point at which you look for the underlying PH. If you study the patients early, the prevalence is likely to be a little lower. If you perform an RHC later in the disease course, it makes intuitive sense that it's going to be higher. Supportive of this notion, our group did have an abstract at the Chest meeting last year looking at serial change in pulmonary pressures in patients with IPF.^[4] We had about 40 patients in this study. We looked at the initial RHC data at the time of evaluation for transplantation, and compared this with the RHC data in the operating room (OR) at the time of transplantation, before any incisions had been made. What we showed in that population was that the prevalence of PH was once again about a third of patients initially, but by the time they got to the OR and were recatheterized, the prevalence was up to 85%. In a similar study, the prevalence of PH at the time of lung transplantation was found to be in excess of 90%.^[5] So not only does it seem "usual," but one could argue that it might be inevitable that IPF patients will develop PH at some point in their disease course.

Posted 08/15/2006

References

Disclosure: Steven D. Nathan, MD, has disclosed no relevant financial relationships.