Early thrombolysis in acute myocardial infarction: Limitation of infarct size and improved survival

Abstract

The effect of thrombolysis in acute myocardial infarction on infarct size, left ventricular function, clinical course and patient survival was studied in a randomized trial comparing thrombolysis (269 patients) with conventional treatment (264 control patients). All 533 patients were admitted to the coronary care unit within 4 hours after the onset of symptoms related to the infarction. Baseline characteristics were similar in both groups. Informed consent was requested only of patients allocated to thrombolysis; no angiography was performed in 35. The infarct-related artery was patent in 65 patients and occluded in 169. Recanalization was achieved in 133 patients. The median time to angiographic documentation of vessel patency was 200 minutes after the onset of symptoms. The clinical course in the coronary care unit was more favorable after thrombolysis. Infarct size, estimated from myocardial enzyme release, was 30% lower after thrombolysis. In patients admitted within 1 hour after the onset of symptoms the reduction of infarct size was 51%, in those admitted between 1 and 2 hours it was 31% and in those admitted later than 2 hours it was 13%. Left ventricular function measured by radionuclide angiography before hospital discharge was better after thrombolysis (ejection fraction 48 +/- 15%) than in control patients (44 +/- 15%). Similar improvement was observed in patients with a first infarct only (thrombolysis 50 +/- 14%, control subjects 46 +/- 15%), in patients with anterior infarction (thrombolysis 44 +/- 16%, control subjects 35 +/- 14%) and in those with inferior infarction (thrombolysis 52 +/- 12%, control subjects 49 +/- 12%). Similar results were obtained by contrast angiography. Mortality was lower after thrombolysis. After 28 days 16 patients allocated to thrombolysis and 31 control patients had died. One year survival rates were 91 and 84%, respectively. On the other hand, nonfatal reinfarction occurred more frequently after thrombolysis (36 patients) than in control subjects (16 patients). Early thrombolysis by intracoronary streptokinase leads to a smaller infarct size estimated by enzyme release, preserves left ventricular function at the second week and leads to improved 1 year survival.

Quantitative analysis of infarct size, contraction band necrosis, and coagulation necrosis in human autopsied hearts with acute myocardial infarction after treatment with selective intracoronary thrombolysis.

“…More of the left ventricular wall was infarcted in patients who died of congestive heart failure than in those who died of cardiac rupture. These findings are similar to those reported in patients without coronary thrombolysis who died of AMI 16,20,21 The present data revealed that (1) there was no significant difference in the infarct size/risk area ratio between groups I and II, (2) CBN was diffusely present in group I but almost absent in group II, (3) the infarct size/risk area ratio and the percentage of the infarct containing CBN varied considerably in group III.…”

“…Hence, the results may be most applicable to this subgroup of patients. CBN is considered to be caused by (1) reperfusion after ischemia or anoxia, "0"2 (2) Therefore it is necessary to develop methods to protect against CBN to reduce infarct size in human AMI.…”

Serum markers for early diagnosis of non-‘Q’ wave and ‘Q’ wave myocardial infarction

“…The size of the infarct depends mostly on the distribution of the occluded artery, though the collaterals may limit it to the subendocardial layer (2). Early thrombolytic treatment limits the size of the infarct (3,4). Therefore early identification and confirmation of AMI are essential for rapid and correct decision making and patient care.…”

Thrombolysis with Intracoronary Administration of YM866, a Novel Modified Tissue-Type Plasminogen Activator, in a Canine Model of Coronary Artery Thrombosis

“…The benefit of thrombolysis is enhanced by early treat ment and the re-establishment of coronary patency (8). This requirement makes widespread intracoronary (i.c.)…”