Intravenous streptokinase in acute myocardial infarction: experience of community hospitals served by paramedics

Psychosocial risk factors of myocardial infarction and adverse effects of streptokinase in public sector hospitals

OBJECTIVES

This study investigated the psychosocial risk factors of myocardial infarction and time related adverse effects of administration of streptokinase on short-term morbidity and mortality in patients with ST-segment-elevation myocardial infarction (STEMI).

METHODS

One hundred patients with STEMI treated with streptokinase in the hospital setting were prospectively enrolled in the study. The primary outcome parameter was the incidence of major adverse cardiac events. During hospital stay the psychosocial and demographic risk factors were also investigated.

RESULTS

The overall mortality rate was similar in both groups and it was not significant. (5.7% vs 14.5%; P = 0.18). The number of recurrent chest pain was significantly higher in the group 2 compared to the group 1 (25% vs 62.5%; P = .01). The number of hypotesion was significantly higher in the group 1 as compared to the group 2 (30.7% vs 6.2%; P = .009). The demographic and psychosocial risk factors were recorded.

CONCLUSIONS

The early intravenous administration of streptokinase in the hospital setting leads to a reduced rate of major cardiovascular events compared to delayed administration beyond 2 hours. However, mortality rates were not significantly affected. Secondary prevention should be targeted on modifiable demographic, dietary, and psychosocial risk factors of STEMI.

Prehospital thrombolysis in rural emergency room and subsequent transport to a coronary care unit: Ravenna Myocardial Infarction (RaMI) trial

OBJECTIVE

To assess the feasibility, safety and efficacy of thrombolysis in the Emergency Room of a Rural Hospital with no Coronary Care Unit, and subsequent transfer to the Coronary Care Unit of a City Hospital.

DESIGN

Prospective study, controlled with two parallel groups of consecutive patients (Group 1: Rural Hospital, Group 2: CCU Ravenna) and administration of Anistreplase 30 intravenous unit.

SETTING

Rural Emergency Rooms which transmitted the electrocardiogram by cardiotelephone to the Ravenna Coronary Care Unit (average distance 35 km; range: 17-50 km).

PATIENTS

280 (Group 1: 102 patients, Group 2: 178 patients) with suspected acute myocardial infarction and with no contra-indications to fibrinolysis, within 6 h of onset of symptoms.

MAIN OUTCOME MEASURES

time saving, accuracy of diagnosis, adverse events, left ventricular function and survival.

RESULTS

the median pain to needle time was 90' in Group 1 and 165' in Group 2 (P < 0.001). Accuracy of diagnosis for acute myocardial infarction was 91% and 100%, respectively. Complications were rare and none occurred during transfer. The creatine phosphokinase peak of Group 1 was lower than Group 2 (1389 vs. 2186 IU/l; P < 0.001). The echocardiographic Wall Motion Abnormality Score Index of Group 1 was lower than Group 2 (3.571 vs. 5.589; P < 0.001). Mortality at 35 days in Group 1 was 7.5% vs. 10.7% in Group 2 (-30%; P = n.s.).

CONCLUSIONS

The Emergency Room physician, in close collaboration with the cardiologist, supplied a very high standard of pre-Coronary Care Unit diagnosis and therapy. Administration of Anistreplase in the rural Emergency Room brought about a significant reduction of pain to needle time, a significant improvement in left ventricular function and a reduction in mortality.

Defibrotide versus heparin in the prevention of coronary reocclusion after thrombolysis in acute myocardial infarction

A multicenter controlled study versus heparin was conducted to explore the activity of defibrotide, a polydesoxyribonucleotide drug, in preventing reocclusion after urokinase thrombolysis in patients with acute myocardial infarction (AMI). The study involved 137 consecutive patients with AMI and a time from the onset of symptoms < or = 6 hours, treated with urokinase (1,000,000 U intravenous bolus followed by 1,000,000 U slow-drip infusion over 12 hours). Immediately after thrombolysis, patients were allocated to treatment with defibrotide (group D: day 0, 3.6 g by intravenous infusion in 12 hours; days +1 to +6, 800 mg tid intravenously; days +7 to +10/+12, 400 mg tid intramuscularly), or heparin (group H: day 0, 1000 IU/hour infused over 12 hours; days +1 to +10/+12, 5000 IU tid subcutaneously). Coronary angiography was done, whenever possible, at +10/+12 days. The following parameters were assessed: (a) noninvasive estimate of myocardial reperfusion, through the analysis of CPK time-activity curves; (b) incidence of infarct-related artery (IRA) patency (TIMI scores 2-3) at coronary angiography. A total of 125 patients had a complete enzymatic curve (63 in group D and 62 in group H) and 106 had coronary angiography as well. IRA patency (the main end point) was observed in 63% of group D versus 43% of group H patients (p = 0.07). No statistically significant differences were found in the proportion of patients with indirect signs of early reperfusion (63% in group D versus 52% in group H patients).(ABSTRACT TRUNCATED AT 250 WORDS)

Prehospital Thrombolysis in Acute Myocardial Infarction

Introduction:

The effectiveness and safety of thrombolytic treatment (TT) for acute myocardial infarction (AMI) in the prehospital setting have not been defined. Therefore, its use on a mobile coronary care unit (MCCU) was studied.

Methods:

A MCCU was provided with the equipment and supplies necessary for the administration TT and its personnel were trained in the indications for TT and in its administration. When an emergency medical team physician suspected the diagnosis from the presence of chest pain typical of an AMI, the patient's ECG was transmitted to the Cardiological Consulting Center. If the S-T segments were elevated and the patient met all of the screening criteria, the cardiologist ordered the MCCU personnel to carry out TT. Streptokinase (Avelyzin, Germed, GDR) was administered intravenously at a dose of 500,000 UE.

Results:

Sixty-seven patients with AMI were included in the trial. The mean interval between the onset of the symptoms and the beginning of the TT was 156±77 minutes; it was less than 3 hours for 54 patients. Thirty-four patients (50.7%) had non-invasive markers of successful reperfusion, while 33 (49.3%) did not. Three patients had non-fatal ventricular fibrillation (VF), ventricular tachycardia (VT) and/or ventricular premature beats of high grades (Lown classes 3–5) developed in six and 22 patients respectively. Five patients had conduction disturbances, and 40 had symptomatic hypotension. None of the patients died before arrival at the hospital. Four suffered reinfarction, and one died of VF during the in-hospital phase of care. Post-discharge follow-up (17.5±5.0 months) demonstrated a positive exercise test in 23 (43%), and a left ventricular ejection fraction >80% in 29 (85.2%) and <40% in five (14.8%) of the patients. The in-hospital and post-discharge mortalities were 1.5 and 4.8% respectively. There was not a single case of bleeding sufficient to require a transfusion.

Conclusions:

The study indicates that the administration of TT for AMI in the prehospital setting is both safe and effective.

Reducing time delays in the administration of thrombolytic therapy to patients with acute myocardial infarction

The extent of myocardial damage occurring during acute myocardial infarction is time dependent. Current approaches designed to reduce the time between symptom onset and the initiation of thrombolytic therapy have focused on increasing public awareness of the need to seek prompt medical attention, prehospital administration of thrombolytic agents, and reducing inhospital delays in initiation of therapy. Results from short-term, public awareness campaigns suggest that patient delays in seeking medical assistance can be reduced in some communities; however, these campaigns do not influence overall patient use of emergency rooms and emergency transport services. In addition, the long-term benefit of media campaigns has not been demonstrated. Prehospital thrombolytic therapy appears to be feasible and safe in certain communities, but definite therapeutic benefit of the small time savings realized in studies to date has not been seen. Even if prehospital thrombolysis is proven to benefit selected patients, it will not affect the large number of patients who choose not to use emergency medical transport services. Adherence to established protocols designed to facilitate rapid institution of thrombolytic therapy can reduce inhospital delays. Initiating thrombolytic therapy within 30 minutes of patient arrival in the emergency department is a goal that should be readily achievable in today's healthcare environment.

Evaluation of patients for the need of thrombolytic therapy in the prehospital setting

Maximum benefit from thrombolytic therapy in acute myocardial infarction is obtained with early therapy. The earliest possible time to treat is during the initial evaluation of the patient in the home or ambulance, which requires accurate diagnosis of acute myocardial infarction in the prehospital setting. In our study, paramedics evaluated patients who had chest pain with a 12-lead ECG transmitted by cellular telephone and a checklist for inclusion and exclusion criteria for thrombolytic therapy. This information was transmitted to a hospital-based telemetry physician who diagnosed or excluded acute myocardial infarction and made a mock decision to withhold or administer a thrombolytic agent. Forty-eight patients with chest pain were evaluated. Six were diagnosed as having overt acute myocardial infarction by the hospital-based telemetry physician. All six patients had the diagnosis substantiated by both ECG and enzyme studies on hospital admission. Based on the data supplied by paramedics, two of these six patients were considered eligible for thrombolytic therapy by the physician. Hospital evaluation confirmed the prehospital decision to treat with a thrombolytic agent. In addition, all other patients were appropriately diagnosed as ineligible. Prehospital ECG diagnosis resulted in two patients going directly to the catheterization lab, thereby bypassing the emergency department. Overt acute myocardial infarction can be accurately identified by a prehospital-acquired 12-lead ECG transmitted to a hospital-based physician. Our study demonstrates that in conjunction with specially trained paramedics, the hospital physician can decide whether to administer thrombolytic therapy to such patients in the prehospital setting.

Innovative approaches to plasminogen activator therapy

Plasminogen activator therapy for acute myocardial infarction has become standard medical practice. Bleeding complications, however, limit the utility of the currently available agents. This article reviews how the tools of molecular biology and protein engineering are being used to develop safer and more effective plasminogen activators.

A system approach to intravenous thrombolysis in acute myocardial infarction in community hospitals: the influence of paramedics

During a 3-year period, intravenous streptokinase (IV STK) was given to 110 consecutive patients ages 34-78 in the course of acute myocardial infarction (AMI) in three community hospitals served by the same paramedic system. 1.5 million units of IV STK was given over 30 minutes. Half of the patients were brought to the hospital by paramedics. The average time from onset of pain to administration of IV STK was 107 minutes in the paramedic group and 182 minutes for the others. Of 110 patients, 98 (89%) showed clinical evidence of reperfusion and 94 of 106 patients (89%) showed angiographic reperfusion. Angiography was performed from 1 to 10 days post-AMI. Mean time to angiography was 6 days for the first 58 patients and 2 days for the last 52 patients. In-hospital mortality was 2 of 110 patients and there was 1 late death at 8 months for an overall 3-year mortality 2.7%. Of 86 patients, 83 (96%) working before their infarct are working now. Of 107 survivors, 96 (90%) are Functional Class I.

CONCLUSIONS

(1) IV STK is safely administered in a high percentage of AMI patients. (2) IV STK is safely administered in community hospitals. (3) Paramedics act as an early warning system and allow for earlier treatment than patients presenting without paramedic involvement. (4) Successful coronary reperfusion with IV STK results in low mortality rates and minimizes functional disability. (5) A system-wide approach to reducing time to treatment in AMI may be the most influential factor in affecting morbidity and mortality.

The safety of combined thrombolysis and beta-adrenergic blockade in patients with acute myocardial infarction. A randomized study

To assess the safety of combined intervention in acute myocardial infarction, a pilot study of thrombolysis and beta-adrenergic blockade was performed. Twenty-five subjects were randomized to therapy with intravenous (IV) metoprolol and IV streptokinase (group 1) or to IV metoprolol (group 2) alone. Two-dimensional echocardiography was performed before intervention and five days later. The mean time from onset of symptoms to intervention was 1.92 hours. No major adverse reactions related to the intervention were observed in either group. Significant improvement from baseline was observed with combined therapy on both the biplane mean ejection fraction (p less than .02) and a calculated wall motion index of regional wall motion abnormalities (p less than .002). The presumed reperfusion rate was significantly higher in group 1 (p less than .03). Intravenous metoprolol and IV streptokinase in combination was found to be safe in the acute phase of acute myocardial infarction when administered to appropriate patients without contra-indications and deserves further study.

Short-term infarct vessel patency with aspirin and dipyridamole started 24 to 36 hours after intravenous streptokinase

The duration of intravenous heparin therapy required to maintain patency of the infarct-related artery after intravenous streptokinase is uncertain. Twenty-eight patients were prospectively treated with 1.5 million units of intravenous streptokinase within 4 hours of onset of chest pain. Intravenous heparin was begun after the streptokinase infusion was complete and was discontinued within 36 hours. Aspirin, 325 mg daily, and dipyridamole, 75 mg three times a day, was begun before the heparin was discontinued. Coronary angiography was performed both at 2 hours after completion of the streptokinase infusion and again at a mean of 8.7 (+/- 3.2) days after the initial catheterization. One patient died after treatment with streptokinase but before early angiography. In 21 of 27 patients (78%), Thrombolysis in Myocardial Infarction trial (TIMI) grade 2 or 3 perfusion in the infarct vessel was observed on initial angiography. Repeat angiograms were available in 17 of the 21 patients with initially patent vessels. Continued patency (TIMI grade 2 or 3) was found in 15 of the 17 patients (88%). Two of the four patients who did not undergo repeat angiography died, and the remaining two patients required coronary artery bypass grafting for unstable angina. Bleeding complications occurred in 6 of 27 patients (22%), with two (7%) requiring surgical evacuation of a groin hematoma. There were no instances of intracerebral bleeding and only two patients required transfusions. Thus, the combination of aspirin and dipyridamole following 36 hours of systemic heparinization after intravenous streptokinase infusion is associated with a reocclusion rate comparable to that which has been reported for more prolonged systemic anticoagulation with fewer hemorrhagic complications.