Delayed effects of early infarct-limiting therapies on healing after myocardial infarction

The effect of early infarct-limiting therapy on the hydroxypyroline (OHP, a marker of collagen) content and topography of 7-day-old infarcts was studied in 76 conscious dogs (69 ligated; seven sham operated). Two hours after their left anterior descending coronary arteries were occluded, 69 dogs were randomly assigned to receive 6 hr intravenous infusions of saline (controls; n = 29), low-dose nitroglycerin (NG; n = 13), prostacyclin (PGI2; n = 14), or ibuprofen (IBU; n = 13). Regional OHP (mg/g dry weight) was measured by spectrophotometry, and size of infarction and topography were determined by computerized planimetry. Infarct size was less in the NG, PGI2, and IBU groups compared with that in the saline group, both when measured as a percent of the arteriographic occluded bed (p less than .001) and as a percent of the left ventricle (p less than .005). For each treatment group (1) the level of OHP was higher (p less than .001) in the region of infarction (saline group, 9.9 +/- 0.7 mg/g; NG group, 14.9 +/- 1.9 mg/g; PGI2 group, 12.9 +/- 0.9 mg/g; IBU group, 10.6 +/- 1.4 mg/g) than in normal zones (4.4 +/- 0.2 mg/g), with more (p less than .05) OHP in border than center regions, and (2) the total OHP in the infarct zone was linearly related to size of infarction as a percent of the left ventricle (r = .89 to .94). However, the slopes of regressions for the NG, PGI2, and IBU groups were greater (p less than .001) than the slope for the saline group.(ABSTRACT TRUNCATED AT 250 WORDS)