Increased extravascular lung water in patients with low pulmonary artery occlusion pressure after acute myocardial infarction. OBJECTIVE: To evaluate the clinical characteristics of increased extravascular lung water (EVLW) in patients with low pulmonary artery occlusion pressure (PAOP) in the early phase of acute myocardial infarction. DESIGN: Consecutive sample for descriptions of the clinical features of medical disorders. SETTING: A general medicine group practice in a university hospital. PATIENTS: Sixteen patients with low PAOP (less than 18 mm Hg) on the initial measurement obtained within 12 hr of chest pain onset. MEASUREMENTS AND MAIN RESULTS: EVLW was measured by the thermal indocyanine green dye double-indicator dilution method. QRS score was obtained on hospital day 7 from the Selvester's QRS Scoring System. Eleven (69%) patients had increased EVLW greater than 7 mL/kg despite low PAOP. EVLW had no significant correlation with PAOP and the difference between plasma colloid osmotic pressure and PAOP, but did have a significant correlation with pulmonary vascular resistance index (r2 = .31, p less than .05), and QRS score (r2 = .45, p less than .005). CONCLUSIONS: Larger infarcts led to increased EVLW even with low PAOP, and the accumulation of increased EVLW around the small arterioles might have led to increased pulmonary vascular resistance. 