Safety and efficacy of thrombolysis with alteplase (50 mg) plus tirofiban versus alteplase (100 mg) alone in acute myocardial infarction: preliminary findings

BACKGROUND

The goal of therapy in acute myocardial infarction (AMI) is the complete and timely restoration of coronary blood flow. Platelets have a pivotal role in the pathophysiology of AMI. The study was aimed at evaluating the safety and efficacy of the combination of 50 mg alteplase plus tirofiban vs 100 mg alteplase in AMI patients.

METHODS

One hundred twenty patients (83 males, 37 females; mean age 54.3 +/- 8 years) were hospitalized for suspected AMI within 6 hours of the onset of symptoms. All patients presented pain and persistent ST-segment elevation, were suitable candidates for thrombolysis (1st episode) and were randomized (double blind) into two groups. Group A (n = 60,42 males, 18 females) received 50 mg alteplase (15 mg as bolus, followed by an infusion of 35 mg over 60 min) in combination with tirofiban (0.4 mcg/kg/min for 30 min followed by an infusion of 0.1 mcg/kg/min for 3 days). Group B (n = 60, 41 males, 19 females) received 100 mg of accelerated-dose alteplase alone. Reperfusion criteria were defined as follows: > 50% reduction in the ST-segment elevation; resolution of chest pain; double marker of creatine kinase (CK) and CK-MB activity 2 hours after the start of thrombolysis; reperfusion arrhythmias within the first 120 min of thrombolysis. The blood pressure, heart rate and ECG were continuously monitored. The mortality, re-AMI, recurrent angina, major and minor bleeding, and emergency bypass surgery or coronary angioplasty were checked.

RESULTS

The groups were similar with regard to clinical data, risk factors, time elapsed from the onset of symptoms to thrombolytic therapy and AMI localization. Forty-seven patients (78.3%) from group A showed reperfusion (15-60 min) vs 25 patients (41.7%) from group B (43-105 min after the end of full-thrombolysis, p = 0.01). Group A patients showed an earlier CK peak and lower CK and CK-MB peaks than those in the control group (p = 0.0001, p = 0.011, p = 0.005, respectively). Nine patients (7.5%) died: 6 (10%) in group B and 3 (5%) in group A (p = NS). A non-fatal re-AMI occurred in 8 patients from group A and in 4 patients from group B (p = NS). Recurrent angina occurred in 27 patients (45%) from group A and in 11 (18.3%) from group B (p = 0.037). Twenty-three of these patients underwent urgent coronary angioplasty (17 from group A and 6 from group B) and 3 from group A and 1 from group B underwent urgent coronary artery bypass grafting (p = NS). The frequency of minor bleeding was higher in group A than in group B (56.7 vs 25%, p = 0.033). No major bleeding was observed in the study groups. At the predischarge echocardiogram, the ejection fraction was higher in group A than in group B (50 +/- 9 vs 44 +/- 7%, p = 0.001).

CONCLUSIONS

Our data suggest that the combination of glycoprotein IIb/IIIa inhibitors plus alteplase is feasible in AMI patients and that the increased risk of bleeding is an acceptable risk considering the advantage in terms of the reduction in the extent of an AMI. In addition, this combination can allow one to gain time when it is necessary to perform mechanical revascularization in patients admitted to a hospital without an interventional cardiology laboratory or in those who have to be referred to another hospital for urgent coronary artery bypass grafting.

Structural conservation in single-domain proteins: implications for homology modeling

Large-scale sequencing projects are widening the gap between the known protein universe and the fraction for which structural information has been experimentally obtained. Through the application of homology (comparative) modeling and more general structure prediction techniques, this gap can, however, be narrowed, providing indirect structural information for a considerable number of proteins. Moreover, the estimated number of existing protein folds seems to be limited and many of these yet unknown folds should be discovered by dedicated large-scale structural genomics projects. Within this perspective, homology (comparative) modeling will gain in importance, as will the use of models derived by this technique. Here we discuss how well a sequence alignment, the most common starting point for generating a model, reflects the structural conservation between homologous proteins and we show that sequence information is able to direct construction of acceptable models as far as the structural core is concerned. We also show here that the regions surrounding insertions and deletions are much less conserved than the core and discuss the implications of this observation for loop modeling.

Anionic oligomerization as a route to chain clusters

The combination of two old concepts (the "sigma-donor" capability of M-H bonds and the propensity of unsaturated complexes for addition reactions) has led to the first example of addition oligomerization of an organometallic analogue of olefins: chains containing cis-[Re(CO)4] units joined by Re-H-Re interactions have been obtained through the oligomerization of the unsaturated complex [Re2(micro-H)2(CO)8] promoted by anionic "initiators". The limits of the method and the possible extension to other substrates are discussed.

[Re]

A chair conformation comparable to that observed for six-membered rings composed of tetrahedral carbon atoms is found for the cluster anion [Re(6)(µ-H)(5)(CO)(24)](-) (see picture; black spheres: Re, white spheres: µ-H; CO ligands omitted for clarity) in spite of the octahedral coordination at the Re centers. This is the first example of a carbonyl cluster exhibiting a cyclohexane-like geometry of the metallic framework.