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(Circulation. 1998;98:825-826.)
© 1998 American Heart Association, Inc.

Correspondence

Treatment of Pulmonary Embolism With Thrombolysis

Mark Metersky, MD

Assistant Professor University of Connecticut School of Medicine, Farmington, Conn

To the Editor:

I have read with interest the article by Dr Konstantinides and colleagues¹ regarding clinical outcomes after treatment of pulmonary embolism (PE) with either heparin or thrombolysis. Although not a randomized trial, appropriate multivariate analysis was performed so that although not the "final word," the results might have some validity.

Unfortunately, as published, this study has a tremendous design flaw that could potentially result in a selection bias that is not addressed by the multivariate analysis. Specifically, 27% of the patients did not have confirmation of PE by either ventilation/perfusion scanning or pulmonary angiography. The use of only clinical criteria to diagnose some of these patients (we don't know how many of this group had other studies, such as Doppler ultrasound) is fraught with difficulty. In the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) study, only about a third of patients with suspected PE were found to have PE at angiogram.²

How, then, does this issue result in selection bias? It is probable that physicians would be less likely to give thrombolytic agents to patients without a confirmatory ventilation/perfusion scan or pulmonary angiogram. Because it is almost certain that some of these patients were inaccurately diagnosed with PE, they may not have been receiving appropriate care for their true problem. Therefore, it is possible that patients with cardiopulmonary disease other than PE, who may have been more likely to die secondary to inaccurate diagnosis, were more frequently treated with heparin as opposed to thrombolysis. Given the relatively low . . . [Full Text of this Article]

Stavros Konstantinides, MD

Universitätsklinik, Innere Medizin III, Kardiologie

Manfred Olschewski, PhD

Medizinische Biometrie und Statistik Albert Ludwigs University, Freiburg, Germany