A randomized factorial trial of reperfusion strategies and aspirin dosing in acute myocardial infarction. The DUCCS-II Investigators

The focus of new research efforts to improve the morbidity and mortality associated with acute myocardial infarction (AMI) has turned to adjuvant agents that show promise of improving outcomes following coronary thrombolysis. We enrolled 162 patients with AMI in a randomized trial comparing front-loaded tissue-plasminogen activator (t-PA) plus weight-adjusted heparin with anisoylated plasminogen streptokinase activator complex (APSAC) without heparin as well as standard-dose (325 mg) and low-dose (81 mg) aspirin. The primary end point was an in-hospital morbidity profile; secondary end points were clinical and angiographic potency and hemorrhagic events. Selected sites performed an electrocardiographic substudy to determine the time to 50% ST-segment recovery and the time to steady state. Although the trial was terminated when the Global Utilization of Streptokinase and t-PA for Occluded Coronary Arteries-I trial showed that t-PA had a significant mortality advantage over streptokinase, important trends were evident. Patients given t-PA and heparin were better anticoagulated (p = 0.001), yet AP-SAC-treated patients had more bleeding complications. The primary end point favored t-PA (25.4% vs 31.3%), and the secondary end points were similar in both groups. In the electrocardiographic substudy, the t-PA group achieved both 50% ST-segment recovery and steady-state recovery sooner than the APSAC group. Patients taking low-dose aspirin had lower in-hospital mortality and less recurrent ischemia but more strokes than the standard-dose aspirin group. Thus, this trial demonstrated trends favoring front-loaded t-PA with weight-adjusted heparin over APSAC without heparin in the treatment of AMI. The use of low-dose aspirin did not appear to impose a loss of protection from adverse events, nor did standard-dose aspirin increase serious bleeding.

A randomized trial of intravenous heparin in conjunction with anistreplase (anisoylated plasminogen streptokinase activator complex) in acute myocardial infarction: the Duke University Clinical Cardiology Study (DUCCS) 1

OBJECTIVES

We designed a randomized trial to evaluate the effects of heparin administration in conjunction with anistreplase (anisoylated plasminogen streptokinase activator complex [APSAC]) on arterial patency and clinical end points.

BACKGROUND

The role of conjunctive intravenous heparin therapy with APSAC has not been tested despite the recommendations that intravenous heparin should be used.

METHODS

Four hours after APSAC administration, 250 patients with acute myocardial infarction were randomly assigned to receive 325 mg of either aspirin alone or aspirin and a continuous infusion of heparin (15 IU/kg body weight per h). Clinical ischemic events and bleeding complications were monitored. On hospital day 5, coronary arteriography and left ventriculography were performed.

RESULTS

The primary end point of the trial (the combined outcome of death, reinfarction, recurrent ischemia and occlusion of the infarct-related artery) occurred in 42% of the heparin-treated group versus 43% of the group treated without heparin (p = 0.94). A patent infarct-related artery was present in 80% of the patients treated with heparin and in 73% of those treated without heparin (p = 0.26). Left ventricular function, as measured by ejection fraction, was well preserved in both groups (52% vs. 50.5%, respectively, p = 0.29). The overall bleeding rate was higher in patients with (32%) than without (17.2%) heparin (p = 0.006).

CONCLUSIONS

Weight-adjusted intravenous heparin therapy after APSAC in acute myocardial infarction does not reduce the combined incidence of death, reinfarction, recurrent ischemia and occlusion of the infarct-related artery. Furthermore, withholding intravenous heparin therapy is associated with a 46% reduction in bleeding complications. Our findings do not support the addition of intravenous heparin after APSAC therapy, as currently recommended, and suggest that a strategy of withholding heparin is simpler and safer and does not place the patient at increased risk for ischemic complications after myocardial infarction.

Dose-related efficacy and bleeding complications of double-chain tissue plasminogen activator in acute myocardial infarction. The Wellcome Tissue Plasminogen Activator Study Group

Although the efficacy of recombinant tissue-type plasminogen activator (rt-PA) in acute myocardial infarction has been demonstrated, little formal dose-ranging information is available. This study examined the use of duteplase, the double-chain rt-PA subsequently used in the Third International Study of Infarct Survival, in a multicenter trial of 267 patients with evolving acute myocardial infarction assigned to receive 1 of 6 weight-adjusted doses. The primary end point was infarct vessel patency after 90 minutes of drug infusion. Patency was defined as Thrombolysis in Myocardial Infarction trial grade 2 or 3 perfusion, and was determined by an independent core laboratory masked to treatment assignment. Patency was present in 48% of patients receiving the lowest dose range and 78% of those receiving the highest, with an association between thrombolytic dose and patency (p = 0.009). The frequency of serious bleeding complications also correlated with the total dose of rt-PA infused (p = 0.003). Bleeding complications were primarily related to instrumentation; blood loss requiring transfusion or otherwise deemed clinically significant occurred in 12% of patients (central nervous system hemorrhage occurred in 1.1%). Thus, higher doses of rt-PA are associated both with increased efficacy and increased risk of serious bleeding complications. Weight-adjusted dosing may provide an optimal risk-benefit ratio for thrombolysis during acute myocardial infarction.

Power injection of contrast media during percutaneous transluminal coronary artery angioplasty

Visualization of the coronary arteries during all phases of percutaneous transluminal coronary angioplasty using hand-held contrast media injection devices is suboptimal. Power injection of contrast media for diagnostic coronary cineangiography has been performed in over 18,000 cases without power injector complication. Here we report our experience with 294 patients using power injection for visualization during all phases of PTCA. It provides optimal visualization of the coronary arteries and has not been associated with complications. It is a safe and efficient system with reduction in both the time and radiation exposure required to perform PTCA and allows determination of the adequacy of the result without unnecessary recrossing of the area of dilatation.

Angina and vasospasm at rest in a patient with an anomalous left coronary system

An anomalous left main coronary artery with passage between the right ventricular infundibulum and aortic root has been incriminated as the causation of sudden death in a small number of individuals, many of whom are quite young. Mechanical features such as angulation and compression are most often incriminated. A 59-year-old man with such a coronary anomaly who had chest pain at rest, ST segment elevation, and ventricular tachycardia, but who had no evidence of effort-related myocardial ischemia, is reported. Improvement in the degree of coronary tone in the anomalous left main coronary with intracoronary nitroglycerin administration was demonstrated. This represents the first report of an individual with an anomalous left main coronary system with ventricular tachycardia/ventricular fibrillation and documented vasospasm in the anomalous artery.

Coronary angioplasty for acute mitral regurgitation due to myocardial infarction. A nonsurgical treatment preserving mitral valve integrity

Three patients presented to the cardiac catheterization laboratory with myocardial infarction, severe mitral regurgitation, and pulmonary edema. Two patients were in cardiogenic shock at the time of cardiac catheterization. Percutaneous transluminal coronary angioplasty was done on the occluded artery in all three patients with resolution of the pulmonary edema as well as auscultative evidence of mitral regurgitation. The mean pulmonary wedge pressure dropped from 34 to 10 mm Hg in these patients. Mean follow-up of 11.7 months showed no evidence of clinical heart failure, angina pectoris, or auscultative evidence of mitral regurgitation.

Left main coronary artery embolism: a case report

A 27-year-old man had recurrent myocardial infarction found to be due to coronary embolism to the left main coronary artery with downstream embolization. The presumed etiology of thromboembolism was idiopathic cardiomyopathy. A unique method of treatment with Fogarty catheter retrieval was used.

Migration of epithelial cells in the small intestine of mice perorally infected with coxsackievirus B5

The rate of cell migration in the small intestine during enteric viral infections has not been assessed previously. CD-1 mice (33 days old) were infected perorally with 1.0 X 10(8) plague-forming units of coxsackievirus B5 and 12 hr later were injected intraperitoneally with 2 micron Ci of [3H]thymidine/g of body weight. After 2, 12, 24, 48, 60, and 72 hr, mice were killed, and the small intestine was removed. Specimens obtained at each interval were examined by radioautography; similar specimens were titrated for virus by plaque assay in HeLa cells. In mice perorally infected with coxsackievirus B5, epithelial cells migrated from crypt to villus tip in 60 hr, as compared with 48 hr in uninfected control mice and 24 hr previously reported for mice perorally infected with enteric bacteria (e.g., Salmonella typhimurium). Virus was recovered from intestinal tissue, but no inflammatory response in the limina propria was apparent. These observations are consistent with previous report that substrate absorption rates may be altered during viral and bacterial enteric infection.

Maturation of intestinal defenses against peroral infection with group B coxsackievirus in mice

The intestinal tract of adult mice provides effective protection against peroral infection with group B coxsackievirus. This protective function consists of at least two separate components. One is a barrier effect that prevents virus from passing through the mucosal side of the gut into the circulation. It becomes clearly evident at 18 days of life and is present thereafter. The other is a clearance mechanism that acts to eliminate virus from the enteric tract after infection has occurred. This is first demonstrable at about 14 to 18 days and also persists. The appearance of these protective functions coincides with the known development of enzymatic and morphological changes in the gut associated with the transition from suckling to weanling.