Thrombolytic therapy for acute myocardial infarction

[Myocardial infarction and revascularization. Current indications]

The physiopathologic role of thrombosis in the genesis of myocardial infarction, began to be suspected early in the 20th century but its logical treatment, thrombolysis, was first used on a large scale only ten years ago. Today, it is well established that short, middle and long-term mortality is correlated to coronary permeability, the delay in the revascularization treatment start-up, its efficacy, its swiftness of action, and to the maintaining of permeability following reperfusion. The importance of time elapse before reperfusion is obtained was demonstrated as early as 1986 by the GISSI study. According to this study, the administration of streptokinase (compared to a conventional treatment) reduced mortality at 21 days respectively by 47%, 23%, and 17%, depending on whether patients were treated within one hour, three hours, or between 3 and 6 hours following the onset of the painful symptoms. One of the major teachings of the GUSTO study, reported at the end of 1993, was the confirmation of the so-called "open artery" theory: mortality at 30 days was of 4.5% among patients whose coronary circulation was restored at the 90th minute, whatever thrombolytic treatment was used, compared to 8.9% when the coronary artery remained occluded. The value of aspirin in preserving coronary permeability following thrombolysis was demonstrated by the ISIS-2 study: mortality at 5 weeks was reduced by 23% in the group of patients randomised to receive only aspirin, while it was reduced by 25% in the group of patients randomised to be treated with streptokinase, and by 42% in the group randomised to receive both aspirin and streptokinase, compared to the group who received neither aspirin nor streptokinase. However, mortality during the first days following randomisation was identical among the groups, with or without aspirin, which suggested its action was rather one of prevention against reocclusion than one of accelerating dissolution of the thrombus. However, in spite of improved therapeutical protocols, a normal flow, which is the major criteria for a reduced mortality, is only obtained at the 90th minute in 54% of the patients who were administered the up-to-date treatment ie aspirin-accelerated t-PA-heparin in combination.(ABSTRACT TRUNCATED AT 400 WORDS)

Encapsulation of the thrombolytic enzyme, brinase, in photosensitized erythrocytes: a novel thrombolytic system based on photodynamic activation

In order to circumvent many of the problems associated with the systemic administration of agents used in thrombolytic therapy, it was decided to investigate the possibility of using erythrocytes as carriers and delivery vehicles for these agents. The enzyme brinase, a fibrinolytic enzyme produced by Aspergillus oryzae, was loaded into rabbit erythrocytes using electroporation. The loading index for this enzyme was found to be 60% and incorporation appeared to be relatively stable over a period of 4 h. In order to facilitate the predetermined release of the loaded component from the erythrocytes, they were photosensitized using haematoporphyrin derivative (HPD) and release was demonstrated within 5 min of photoactivation. Inclusion of the loaded, photosensitized system into clotting blood and subsequent exposure to light demonstrated almost complete lysis of the clot. We believe that this system exhibits potential for use in thrombolytic therapy.

Long-term prognostic importance of a single pulmonary wedge pressure measurement after myocardial infarction: a ten-year follow-up study

To assess the influence on short- and long-term survival of haemodynamic variables measured after acute myocardial infarction, a 10-year prospective follow-up study was undertaken. A total of 304 patients (259 males, 45 females) discharged from hospital after myocardial infarction and under 66 years of age were studied. Haemodynamic variables measured shortly after admittance included pulmonary wedge pressure, mixed venous oxygen saturation, blood pressure and heart rate. In the analysis, adjustments were made for differences in age, gender, clinical parameters and cardiovascular risk factors. Pulmonary wedge pressure was found to be a strong and independent predictor of both short-term and long-term survival. A gradual increase of the 10-year mortality risk with elevated wedge pressure could be demonstrated (relative risk, 1.09/mmHg; 95% confidence interval, 1.04-1.15). Relative risks of patients in the three highest categories of wedge pressure, 12-15 mmHg, 15-19 mmHg and 19 mmHg and higher, compared with patients in the lowest category, lower than 12 mmHg, were 2.25 (95% CI, 1.11-4.55), 2.43 (95% CI, 1.20-4.92) and 2.57 (95% CI, 1.04-6.37), respectively. The other measured haemodynamic variables were found to be associated with short-term mortality only. In conclusion, haemodynamic measurements after myocardial infarction are of prognostic importance after discharge. A single measurement of an elevated wedge pressure in particular unfavourably influenced both short-term and long-term survival.