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(Circulation. 1998;97:940-941.)
© 1998 American Heart Association, Inc.

Correspondence

Echocardiographic Effects of Prostacyclin?

Ronald W. Day, MD

Division of Pediatric Cardiology, University of Utah, Salt Lake City, Utah

To the Editor:

I read with interest the manuscript by Hinderliter and other members of the Primary Pulmonary Hypertension Study Group entitled "Effects of Long-term Infusion of Prostacyclin (Epoprostenol) on Echocardiographic Measures of Right Ventricular Structure and Function in Primary Pulmonary Hypertension."¹ I was disappointed that the authors stated conclusions with no supporting data. Previously, these authors reported that a 12-week continuous intravenous infusion of prostacyclin improved survival in patients with severe primary pulmonary hypertension.² Hinderliter and associates now claim that a 12-week period of prostacyclin therapy also had important beneficial effects on right ventricular structure and function in this same group of patients. Unfortunately, the results were incompletely reported without appropriate statistical comparisons. The baseline echocardiographic features of treated patients and control subjects were well described. However, corresponding measurements, 12 weeks after randomization, were not reported. Furthermore, the authors reported none of the statistical comparisons between baseline and follow-up measurements. By comparing only the median differences between baseline and follow-up echocardiographic variables, the authors arrived at inappropriate and misleading conclusions. The median differences in most echocardiographic variables were so small that it is unlikely that significant "changes" in right ventricular structure or function occurred in either patient group. The authors have suggested that the effects of prostacyclin on cardiac function may have contributed to improved survival and exercise capacity. However, little attention was given to the possibility of a type II error in overlooking a significantly better baseline performance in the 6-minute walk for patients treated with prostacyclin.

The . . . [Full Text of this Article]

Alan L. Hinderliter, MD

Department of Medicine

Gary Koch, PhD

Department of Biostatistics

Tonya Sharp, MS

Department of Biostatistics

Park W. Willis, IV, MD

Departments of Medicine and Pediatrics

Walker Long, MD

Department of Pediatrics, University of North Carolina, Chapel Hill, North Carolina