Chronic Thromboembolic Pulmonary Hypertension
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《新英格兰医药杂志》
To the Editor: Pengo et al. (May 27 issue)1 report an incidence of chronic thromboembolic pulmonary hypertension (CTPH) of approximately 3 percent (diagnosed in 7 of 223 patients) after a first episode of pulmonary embolism. We believe that the angiographic criteria used by the authors to diagnose CTPH may underestimate the real incidence of CTPH after pulmonary embolism. Because Pengo et al. focus on large-vessel CTPH, they could have missed cases of CTPH that were caused by small-vessel chronic thromboembolism. At our institution, 15 percent of cases of CTPH are secondary to small-vessel chronic thromboembolism. The diagnosis of CTPH may be further complicated by the fact that very often it is extremely difficult to distinguish between CTPH and a new episode of acute pulmonary embolism. Misclassification of these conditions may lead to bias. Systematically searching for resolution of the first episode of pulmonary embolism with the use of computed tomography or scintigraphy could help to solve this problem.
José R. Pa?o-Pardo, M.D.
Carmen Fernández-Capitán, M.D., Ph.D.
Francisco Arnalich, M.D., Ph.D.
Hospital Universitario La Paz
28046 Madrid, Spain
joserrapa@ya.com
References
Pengo V, Lensing AWA, Prins MH, et al. Incidence of chronic thromboembolic pulmonary hypertension after pulmonary embolism. N Engl J Med 2004;350:2257-2264.
The authors reply: Pa?o-Pardo et al. suggest that we may have missed CTPH because of isolated distal obstruction and may have misclassified CTPH as recurrent pulmonary embolism. We are confident that our diagnostic work-up of patients who presented with dyspnea during follow-up would also have detected small-vessel CTPH and prevented misclassification so far as possible. Indeed, 2 of the 18 patients with CTPH (11.1 percent) had small-vessel CTPH. Of these two patients, one could not be treated surgically because of obstruction in this location, and the other was among the seven patients whose condition remained stable in New York Heart Association class II.
Underestimation of the incidence of CTPH due to misclassification of CTPH as recurrent pulmonary embolism is unlikely to have occurred in our study, because all patients with recurrent pulmonary embolism remained in follow-up, and a diagnosis of CTPH would have been considered if dyspnea on exertion or at rest had persisted in any of these patients. However, we may have missed patients who had few symptoms of CTPH and those who were asymptomatic. Hence, our estimate of the incidence of CTPH after a first episode of pulmonary embolism should indeed be viewed as a lower limit.
Anthonie W.A. Lensing, M.D.
Academic Medical Center
1105 AZ Amsterdam, the Netherlands
awalensing@planet.nl
Martin H. Prins, M.D.
Academic Hospital Maastricht
6229 HX Maastricht, the Netherlands
Vittorio Pengo, M.D.
University Hospital Padua
35128 Padua, Italy
José R. Pa?o-Pardo, M.D.
Carmen Fernández-Capitán, M.D., Ph.D.
Francisco Arnalich, M.D., Ph.D.
Hospital Universitario La Paz
28046 Madrid, Spain
joserrapa@ya.com
References
Pengo V, Lensing AWA, Prins MH, et al. Incidence of chronic thromboembolic pulmonary hypertension after pulmonary embolism. N Engl J Med 2004;350:2257-2264.
The authors reply: Pa?o-Pardo et al. suggest that we may have missed CTPH because of isolated distal obstruction and may have misclassified CTPH as recurrent pulmonary embolism. We are confident that our diagnostic work-up of patients who presented with dyspnea during follow-up would also have detected small-vessel CTPH and prevented misclassification so far as possible. Indeed, 2 of the 18 patients with CTPH (11.1 percent) had small-vessel CTPH. Of these two patients, one could not be treated surgically because of obstruction in this location, and the other was among the seven patients whose condition remained stable in New York Heart Association class II.
Underestimation of the incidence of CTPH due to misclassification of CTPH as recurrent pulmonary embolism is unlikely to have occurred in our study, because all patients with recurrent pulmonary embolism remained in follow-up, and a diagnosis of CTPH would have been considered if dyspnea on exertion or at rest had persisted in any of these patients. However, we may have missed patients who had few symptoms of CTPH and those who were asymptomatic. Hence, our estimate of the incidence of CTPH after a first episode of pulmonary embolism should indeed be viewed as a lower limit.
Anthonie W.A. Lensing, M.D.
Academic Medical Center
1105 AZ Amsterdam, the Netherlands
awalensing@planet.nl
Martin H. Prins, M.D.
Academic Hospital Maastricht
6229 HX Maastricht, the Netherlands
Vittorio Pengo, M.D.
University Hospital Padua
35128 Padua, Italy