The value of right atrial emptying rate in predicting reduction in pulmonary artery pressure in patients with chronic obstructive pulmonary disease.

Abstract

We used an improved noninvasive radionuclide method, recently developed by us, to evaluate changes in pulmonary artery pressure induced by sublingual nifedipine in patients with chronic obstructive pulmonary disease and pulmonary hypertension. The new method enhances the predictive power of right ventricular ejection fraction by using the right atrial emptying rate as an index of reduced right ventricular compliance. The results were compared to those of invasively measured pulmonary arterial pressure. In the 21 patients studied 20 mg of nifedipine sublingually reduced pulmonary arterial pressure by 13.35% from 36.95 +/- 13.95/12.71 +/- 6.24 (mean 20.79 +/- 8.19) mmHg to 32.67 +/- 12.17/10.9 +/- 6.2 (mean 18.16 +/- 7.3) mmHg (p less than 0.05 for all pressures). Cardiac index increased and the pulmonary and systemic resistances decreased. The percent changes in right atrial emptying rate showed an excellent correlation with the percent change in pulmonary pressure. An increase of 12% or more in right atrial emptying rate predicted in all patients a reduction in pulmonary arterial pressure of at least 8%, the specificity and positive predictive accuracy being 100%. The sensitivity and the predictive accuracy of a negative test were 93% and 80%, respectively. The new method is useful for long-term evaluation of drug therapy in patients with pulmonary hypertension.