Abstracts From the Literature-Cardiology Selected by Joseph E. Parrillo, Robert Cunnion, and Gary Schaer

Effectiveness of Intravenous Thrombolytic Treatment in Acute Myocardial Infarction. Gruppo Italian0 per lo Studio Della Streptochinasi Nell’lnfarto Miocardico (GISSI). Lan- cet 1, 1986.

In an unblinded trial of intravenous streptokinase (SK) in early acute myocardial infarction, 11,806 patients in one hundred and seventy-six coronary care units were enrolled over 17 months. Patients admitted within 12 h after the onset of symptoms and with no contraindications to SK were randomised to receive SK in addition to usual treatment and complete data were obtained in 11,712. At 21 days overall hospital mortality was 10.7% in SK recipients versus 13% in controls, an 18% reduction (p = 0.0002, relative risk 0.81). The extent of the beneficial effect appears to be a function of time from onset of pain to SK infusion (relative risks 0.74, 0.80, 0.87, and 1.19 for the O-3, 3-6, 6-9, and 9-12 h subgroups). SK seems to be a safe drug for routine adminis- tration in acute myocardial infarction. (Reprinted with per- mission.)

Early Thrombolysis in Acute Myocardial Infarction: Limita-

tion of Infarct Size and Improved Survival. Simoons ML. Serruys PW, van den Brand M, et al. J Am Co11 Cardiol 7~717, 1986.

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 per- formed 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 documenta-

tion 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 throm- bolysis. 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 hospi- tal discharge was better after thrombolysis (ejection fraction 48 i 15%) than in control patients (44 f 15%). Similar improvement was observed in patients with a first infarct only (thrombolysis $0 i- 14%, control subjects 46 + 15%), in patients with anterior infarction (thrombolysis 44 + 16%, control subjects 35 k 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

144

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. (Re- printed with permission.)

Time From Onset of Symptoms to Thrombolytic Therapy: A Major Determinant of Myocardial Salvage in Patients With Acute Transmural Infarction. Mathey DG, Sheehan FH, Schafer J, et al. J Am Co11 Cardiol6:518, 1985.

To determine whether myocardial salvage after successful intracoronary or intravenous thrombolysis is time dependent, the relation between left ventricular wall motion and the time to treatment was studied in 69 patients admitted less than 3 hours after onset of acute transmural myocardial infarction (42 patients with reperfusion by intracoronary streptokinase, 27 by intravenous urokinase). A similar significant relation between the time to treatment and the severity of regional hypokinesia at follow-up was found in the intracoronary and intravenous groups. To better define this relation, particu- larly during the early phase of infarction, the groups were combined. In patients in whom thrombolytic treatment was initiated within 2 hours after symptom onset, wall motion at follow-up was within 2 standard deviations of the normal mean in 82% (14 of 17 patients). If treatment was started 2 to 5 hours after symptom onset, the probability of improved wall motion decreased to 46% (24 of 52 patients, p < 0.025). The time/wall motion relation appeared to be independent of infarct location, angiographically visible collateral vessels and the presence of subtotal coronary artery occlusion. The severity of hypokinesia at follow-up study correlated with the magnitude of peak serum creatine kinase (r = -0.71), indicating that thrombolytic therapy initiated within 2 hours after the onset of symptoms improves regional left ventricular function and reduces infarct size more than later therapy does. (Reprinted with permission.)

Creatine Kinase Release Not Associated With Myocardial Necrosis After Short Periods of Coronary Artery Occlusion

in Conscious Baboons. Heyndrickx GR, Amano J, Kenna T, et al. J Am Co11 Cardiol6:1299, 1985.

The effects of 15 minute periods of coronary artery occlu- sion on plasma creatine kinase (CK) and CK-MB isoenzyme activity, regional myocardial function and subsequent myo- cardial necrosis were studied in six conscious baboons 2 to 3 weeks after recovery from instrumentation. Mid left anterior descending coronary artery occlusion induced complete loss of systolic wall thickening (ultrasound transit time tech- nique) and decreases in epicardial (-93%) and endocardial (~ 96%) blood flows (microsphere technique). Reperfusion after 15 minutes resulted in complete recovery of regional function 24 hours later. Serial plasma enzyme activity revealed a significant increase in total CK from 71 * 11 to 976 2 158 U/liter and in CK-MB from levels that were too low to measure to 21.4 e 2.9 U/liter. At autopsy, neither gross pathologic evidence (triphenyltetrazolium chloride staining technique) nor histologic evidence of myocardial

~ourna/ofCr;tica/ Care, Vol 2, No 2 (June), 1987: PP 144-151