Guidelines for the use of intravenous thrombolytic agents in acute myocardial infarction. Ontario Medical Association Consensus Group on Thrombolytic Therapy.

A consensus group convened under the auspices of the Ontario Medical Association produced guidelines for the use of intravenous thrombolytic agents in acute myocardial infarction. The guidelines, updated to December 1988, include the following points. 1) Any hospital that routinely accepts the responsibility for looking after patients with acute myocardial infarction could offer thrombolytic therapy if monitoring facilities are available and if the staff are experienced in the treatment of cardiac rhythm disturbances. 2) Before treatment, all patients must be carefully screened for factors predisposing to hemorrhagic complications. 3) A physician should be clearly designated as responsible for the care of the patient receiving an infusion and be available in the event of problems. 4) For the two approved agents the usual dosages are as follows: streptokinase, 1.5 million units given over 1 hour; and tissue-type plasminogen activator (tPA), 100 mg over 3 hours, delivered as 60 mg in the first hour (of which 6 to 7 mg should be given as a bolus in the first 1 to 2 minutes) and then an infusion of 20 mg/h over the next 2 hours. 5) Intravenous thrombolytics should be considered for any patient with presumed acute myocardial infarction, as suggested by prolonged chest pain or other appropriate symptoms and typical electrocardiographic changes. Expeditious treatment is critical, since myocardial necrosis occurs within hours. 6) Emergency angiography is indicated for patients with hemodynamic compromise and no apparent response to streptokinase or tPA and in those with recurrent chest pain suggestive of acute myocardial infarction despite an apparent response to intravenous thrombolysis. Angiography before discharge is recommended for patients with postinfarction angina or evidence from noninvasive testing of significant residual ischemic risk. 7) There is insufficient evidence to choose between streptokinase and tPA on the basis of the two most important outcome measures: patient survival and myocardial preservation. More conclusive evidence comparing tPA, streptokinase and another promising agent, acylated plasminogen-streptokinase activator complex, will be available in 1989-90.     

Teesside coronary survey: an epidemiological study of acute attacks of myocardial infarction.

A 12-month epidemiological survey of attacks of acute myocardial infarction was carried out in a large urban population. The incidence and mortality at all ages and in both sexes were examined. Altogether, 1938 attacks were diagnosed--an overall incidence of 4-89 per 1000 population. The 28-day fatality rate was 50-5%. A third of the patients were treated at home and these patients had a lower fatality rate than those in hospital, a difference that could not be attributed to age, sex, or severity of attack. Half of the deaths that were witnessed occurred suddenly and a further 21% occurred within the next two hours. The median time to patients coming under care was about three hours. As used at present, coronary care units are unlikely to improve fatality rates. Future advances in treatment must take place outside hospital and will require re-education of the public and the general practitioner.     

Acute Myocardial Infarction: Home and Hospital Treatment

This is a preliminary report of a co-operative study of 1,203 episodes of acute myocardial infarction in men under 70 years in four centres in the south west of England. The mortality at 28 days was 15%. A comparison is made between home care by the family doctor and hospital treatment initially in an intensive care unit: 343 cases were allocated at random. The randomized groups do not differ significantly in composition with respect to age; past history of angina, infarction, or hypertension; or hypotension when first examined. The mortality rates of the random groups are similar for home and hospital treatment. The group sent electively to hospital contained a higher proportion of initially hypotensive patients whose prognosis was bad wherever treated; those who were not hypotensive fared rather worse in hospital.For some patients with acute myocardial infarction seen by their general practitioner home care is ethically justified, and the need for general admission to hospital should be reconsidered.     

High mortality in obese women diabetics with acute myocardial infarction.

The factors associated with mortality in 89 diabetics and 793 non-diabetics with acute myocardial infarction who were initially admitted to a coronary care unit were analysed retrospectively. During their stay in hospital diabetics had twice the mortality of non-diabetics. The higher mortality among diabetics was largely accounted for by obese women, who had a hospital mortality of 43%. There was an increased incidence of congestive heart failure in such patients. A therapeutic trial should be performed in such patients to assess whether insulin has an effect on infarct size.     

Evolution of emergency cardiac care in Canada.

Acute myocardial infarction is the most common cause of death in Canada. Most deaths occur within the first 2 hours of the onset of symptoms, before the person seeks or is able to obtain medical aid, and are due to arrhythmias rather than massive myocardial damage. Effective electrical and drug treatment of arrhythmias has reduced the hospital mortality but not the community mortality. If mortality from acute myocardial infarction and other causes of sudden unexpected death is to be reduced substantially a major reorganization of emergency medical services is needed so that the benefits of the modern coronary care unit can be provided to the patient as rapidly as possible. Public education in basic life support procedures to sustain life until advanced life support aid arrives is the first step towards the development of a more effective system of emergency cardiac care.     

Myocardial infarction: a comparison between home and hospital care for patients.

To compare the results of home and hospital treatment in men aged under 70 years who had suffered acute myocardial infarction within 48 hours 1895 patients were considered for study in four centres in south-west England. Four-hundred-and-fifty patients were randomly allocated to receive care either at home by their family doctor or in hospital, initially in an intensive care unit. The randomised treatment groups were similar in age, history of cardiovascular disease, and incidence of hypotension when first examined. They were followed up for up to a year after onset. The mortality rate at 28 days was 12% for the random home group and 14% for the random hospital group; the corresponding figures at 330 days were 20% and 27%. On average, older patients and those without initial hypotension fared rather better under home care. The patients who underwent randomisation were similar to those whose place of care was not randomised, except that the non-randomised group contained a higher proportion of initially hypotensive patients, whose prognosis was poor wherever treated. These results confirm and extend our preliminary findings. Home care is a proper form of treatment for many patients with acute myocardial infarction, particularly those over 60 years and those with an uncomplicated attack seen by general practitioners.     

Comparison of Mobilization after Two and Nine Days in Uncomplicated Myocardial Infarction

A total of 189 patients with uncomplicated myocardial infarction were selected at random for early or late mobilization and discharge from hospital. Patients were admitted to the study after 48 hours in a coronary care unit if they were free of pain and showed no evidence of heart failure or significant dysrhythmia. Randomization was achieved by monthly cross-over of the three medical wards to which the patients were discharged. One group of patients was mobilized immediately and discharged home after a total of nine days in hospital, and the second group was mobilized on the ninth day and discharged on the 16th day. Out-patient assessment was carried out six weeks after admission. No significant differences were observed between the groups in terms of mortality or morbidity, as reflected by the incidence of recurrent chest pain or myocardial infarction, heart failure, dysrhythmia, or venous thromboembolism detected either clinically or by ¹²⁵I-labelled fibrinogen scanning.     

Inpatient deaths from acute myocardial infarction, 1982-92: analysis of data in the Nottingham heart attack register.

OBJECTIVE: To assess longitudinal trends in admissions, management, and inpatient mortality from acute myocardial infarction over 10 years. DESIGN: Retrospective analysis based on the Nottingham heart attack register. SETTING: Two district general hospitals serving a defined urban and rural population. SUBJECTS: All patients admitted with a confirmed acute myocardial infarction during 1982-4 and 1989-92 (excluding 1991, when data were not collected). MAIN OUTCOME MEASURES: Numbers of patients, background characteristics, time from onset of symptoms to admission, ward of admission, treatment, and inpatient mortality. RESULTS: Admissions with acute myocardial infarction increased from 719 cases in 1982 to 960 in 1992. The mean age increased from 62.1 years to 66.6 years (P < 0.001), the duration of stay fell from 8.7 days to 7.2 days (P < 0.001), and the proportion of patients aged 75 years and over admitted to a coronary care unit increased significantly from 29.1% to 61.2%. A higher proportion of patients were admitted to hospital within 6 hours of onset of their symptoms in 1989-92 than in 1982-4, but 15% were still admitted after the time window for thrombolysis. Use of beta blockers increased threefold between 1982 and 1992, aspirin was used in over 70% of patients after 1989, and thrombolytic use increased 1.3-fold between 1989 and 1992. Age and sex adjusted odds ratios for inpatient mortality remained unchanged over the study period. CONCLUSIONS: Despite an increasing uptake of the "proved" treatments, inpatient mortality from myocardial infarction did not change between 1982 and 1992.     

Relation of trauma to disease; aspects of correlation in cases involving compensation

As a general rule, it is not believed possible to classify patients with acute myocardial infarction as to the future severity of their illness at the time of the initial examination. However, classifications are possible from complete clinical data of the first few days with regard to the predicted mortality rates. Whether to manage the patient in the hospital or at home depends on the community facilities. The patient should be in bed for a period of two to three weeks if unquestioned infarction has occurred. The main avenue of investigation as to lowering of mortality needs to be directed toward the prevention of heart failure or sudden unexpected death probably related to arrhythmia. If the patient is hospitalized and laboratory facilities are available, anticoagulant therapy can be safely and effectively carried out without undue risk or prohibitive increase in the cost of management. The experience of the author and his colleagues has led to the belief that anticoagulants given routinely to patients with myocardial infarction are effective in decreasing the incidence of thromboembolic complications.     

ACUTE MYOCARDIAL INFARCTION—A Discussion of Certain Controversial Issues

As a general rule, it is not believed possible to classify patients with acute myocardial infarction as to the future severity of their illness at the time of the initial examination. However, classifications are possible from complete clinical data of the first few days with regard to the predicted mortality rates. Whether to manage the patient in the hospital or at home depends on the community facilities. The patient should be in bed for a period of two to three weeks if unquestioned infarction has occurred.The main avenue of investigation as to lowering of mortality needs to be directed toward the prevention of heart failure or sudden unexpected death probably related to arrhythmia. If the patient is hospitalized and laboratory facilities are available, anticoagulant therapy can be safely and effectively carried out without undue risk or prohibitive increase in the cost of management. The experience of the author and his colleagues has led to the belief that anticoagulants given routinely to patients with myocardial infarction are effective in decreasing the incidence of thromboembolic complications.     

Cardiac predictors of death after non-cardiac surgery evaluated by intention to treat.

Cardiac risk factors were studied among patients who were admitted to hospital with appendicitis or a fracture of the proximal femur less than one year after being admitted with myocardial infarction. Of 99 patients with myocardial infarction and appendicitis, 87 underwent appendicectomy; and of 221 with myocardial infarction and hip fracture, 179 were operated on. The patients were studied on an intention to treat basis. The mortality within one month was 9% and 16% respectively. A history of congestive heart failure was the dominating risk factor, while ischaemic heart disease (recent myocardial infarction or angina pectoris) had no independent association with mortality. If the ventricular function is known additional preoperative information about the heart is of negligible value when estimating the mortality of non-cardiac surgery.     

Comparison of case fatality in south Asian and white patients after acute myocardial infarction: observational study.

OBJECTIVE--To compare mortality in south Asian (Indian, Pakistani, and Bangladeshi) and white patients in the six months after hospital admission for acute myocardial infarction. DESIGN--Observational study. SETTING--District general hospital in east London. PATIENTS--149 south Asian and 313 white patients aged < 65 years admitted to the coronary care unit with acute myocardial infarction from 1 December 1988 to 31 December 1992. MAIN OUTCOME MEASURE--All cause mortality in the first six months after myocardial infarction. RESULTS--The admission rate in the south Asians was estimated to be 2.04 times that in the white patients. Most aspects of treatment were similar in the two groups, except that a higher proportion of the south Asians received thrombolytic drugs (81.2% v 73.8%). After adjustment for age, sex, previous myocardial infarction, and treatment with thrombolysis or aspirin, or both, the south Asians had a poorer survival over the six months from myocardial infarction (hazard ratio 2.02 (95% confidence interval 1.14 to 3.56), P = 0.018), but a substantially higher proportion were diabetic (38% v 11%, P < 0.001), and additional adjustment for diabetes removed much of their excess risk (adjusted hazard ratio 1.26 (0.68 to 2.33), P = 0.47). CONCLUSION--South Asian patients had a higher risk of admission with myocardial infarction and a higher risk of death over the ensuing six months than the white patients. The higher case fatality among the south Asians, largely attributable to diabetes, may contribute to the increased risk of death from coronary heart disease in south Asians living in Britain.     

Patient and general practitioner delays in acute myocardial infarction

The longest component of the total delay in coming under coronary care is patient delay, and it has been suggested that public education might be used to make it shorter. The patterns of patient delay were studied in 450 patients with acute myocardial infarction uncomplicated by cardiac arrest out of hospital, of whom 243 had a previous history of ischaemic heart disease. Patient delays had a skewed distribution with a modal delay of up to one hour, a median delay of two hours, and a mean delay of 10 hours. Two thirds of patients had sought help from their general practitioners within four hours of the onset of symptoms. During the first four hours the longer that patients delayed the lower was the subsequent mortality (27%, 18%, and 9% for delays of one hour or less, up to two hours, and up to four hours, respectively), but patients who delayed four to eight hours had the highest mortality of all (38%). Neither the median value nor the pattern of patient delays was altered by a previous history of ischaemic heart disease.There were pronounced differences in doctor delays, depending on the patient''s age, delay time, and ultimate place of treatment, showing that the doctors'' behaviour was influenced before they had seen their patients. Nevertheless, the median total delay for patients aged up to 70 was one hour 35 minutes, and a higher proportion of patients were seen early after infarction than in recent hospital trials of thrombolytic treatment.These findings suggest that the patients'' call for help and the doctors'' response may be at an instinctive level according to the patients'' distress; these patterns of behaviour may be difficult to modify by public education.     

Controlled trial of oxygen in uncomplicated myocardial infarction.

Two-hundred consecutive patients thought to have suffered a myocardial infarction were admitted to a randomised, double-blind controlled trial of oxygen or air administered by MC mask throughout the first 24 hours in hospital. Forty-three patients in whom myocardial infarction was not subsequently confirmed were excluded from the analysis. The remaining air and oxygen groups were comparable except for a significantly higher PaO2 and serum aspartate aminotransferase level in the oxygen group. There was no significant difference in mortality, incidence of arrhythmias, use of analgesics, or systolic time intervals between the two groups, although a higher incidence of sinus tachycardia was found in those given oxygen. There appears to be no evidence of benefit from the routine administration of oxygen in uncomplicated myocardial infarction.     

Survival in acute myocardial infarction; factors observed in 318 patients

Factors influencing survival in a group of 318 cases of acute myocardial infarction were analyzed. The mortality rate for the entire series was 41 per cent. Among the men it was 39.5 per cent; among women, 44.4 per cent. The mortality rate increased with the age of the patient. Twenty-six per cent of all deaths occurred within the first 24 hours, 44 per cent within 72 hours, and 71 per cent within the first week following hospital admission. Increased mortality rate was associated with previous history of congestive failure, myocardial infarction, hypertension or cardiomegaly. As to circumstances immediately preceding an infarction, the only ones that seemed to be related to a high mortality rate were hemorrhage and the postoperative state. Not only the presence but the degree of shock, congestive failure, cyanosis and dyspnea adversely influenced chances for survival. Duration, location, radiation and number of attacks of pain did not appear to be associated with extraordinary mortality rates. Anterior was slightly more common than posterior infarctions, and the mortality rate was much higher. Thromboembolic complications and certain disorders of rhythm and of conduction definitely worsen prognosis. Comparison of average mortality data as reported in different studies on acute myocardial infarction is improper and misleading because of the great differences between the kinds of patients included in various series reported upon. A standard method of grading the severity of acute myocardial infarction would help toward sounder comparisons.     

Feasibility,safety, and efficacy of domiciliary thrombolysis by general practitioners: Grampian region early anistreplase trial. GREAT Group.

OBJECTIVE--To assess the feasibility, safety, and efficacy of domiciliary thrombolysis by general practitioners. DESIGN--Randomised double blind parallel group trial of anistreplase 30 units intravenously and placebo given either at home or in hospital. SETTING--29 rural practices in Grampian admitting patients to teaching hospitals in Aberdeen (average distance 36 (range 16-62) miles). PATIENTS--311 patients with suspected acute myocardial infarction and no contraindications to thrombolytic therapy seen at home within four hours of onset of symptoms. MAIN OUTCOME MEASURES--Time saving, adverse events, Q wave infarction, left ventricular function. RESULTS--Anistreplase was administered at home 101 minutes after onset of symptoms, while anistreplase was given in hospital 240 minutes after onset of symptoms (median times). Adverse events after thrombolysis were infrequent and, apart from cardiac arrest, not a serious problem when they occurred in the community: seven of 13 patients were resuscitated after cardiac arrest out of hospital. By three months after trial entry the relative reduction of deaths from all causes in patients given thrombolytic therapy at home was 49% (13/163 (8.0%) v 23/148 (15.5%); difference -7.6% (95% confidence interval -14.7% to -0.4%), p = 0.04). Full thickness Q wave infarction was less common in patients with confirmed infarction receiving treatment at home (65/122 (53.3%) v 76/112 (67.9%); difference -14.6% (95% confidence interval -27.0% to -2.2%), p = 0.02). CONCLUSIONS--General practitioners provided rapid pre-hospital coronary care of a high standard. Compared with later administration in hospital, giving anistreplase at home resulted in reduction in mortality, fewer cardiac arrests, fewer Q wave infarcts, and better left ventricular function. Benefits were most marked where thrombolytic therapy was administered within two hours of the onset of symptoms.     

Cardiac Monitoring in a Community Hospital—Analysis of 18 Months' Experience

Cardiac monitoring facilities have been present in teaching hospital centers for over five years. A substantial decrease in mortality has been observed in monitored patients with acute myocardial infarction. The community hospital system offers a challenge to effective monitoring since many physicians care for patients and often many kinds of therapy are used.After 18 months of operation mortality from myocardial infarction was only 16.6 percent in a community hospital monitoring unit where the majority of the emergency care and resuscitation was carried out by nurses. Vital to this success was the use of standing orders for nurses, requirement of privilege to practice within the monitoring facility and acceptance of the nurse as a therapist in emergency situations.Fourteen patients were successfully resuscitated and were later discharged from the hospital. Four of them had ventricular fibrillation from digitalis intoxication.Patients with shock and severe congestive heart failure continue to be a major unsolved clinical problem. The results indicate that the potentially viable patient with serious electrical disturbances can almost invariably be salvaged.     

Emergency aorto-coronary venous bypass graft in cardiogenic shock

The mortality rate of shock complicating myocardial infarction is extremely high (80-100%) despite intensive medical management. Five patients with acute myocardial infarction and cardiogenic shock received an emergency aorto-coronary bypass graft, from three hours to five days after the onset of infarction and three to nine hours after the onset of shock. Selective coronary angiography was performed in all cases prior to operation. Four of the five patients survived and were discharged from hospital. Two cases with A-V dissociation and complete heart block reverted to normal sinus rhythm after the operation. This limited experience indicates that emergency aortocoronary bypass graft surgery can reduce mortality significantly in properly selected cases of cardiogenic shock.     

Comparison of mortality of patients with heart attacks admitted to a coronary care unit and an ordinary medical ward.

During a 32-month period 2047 patients suspected of having heart attacks were admitted to hospital and were followed up prospectively. Out of 1480 eventually found to have definite or probable myocardial infarction, 483 had initially been admitted to an ordinary medical ward because of the shortage of coronary care unit (CCU) beds. More patients aged over 65 had been admitted to a ward than to a CCU, and more patients aged 65 or less had been admitted initially to a CCU. Within each age group, however, patients admitted initially to a CCU were clinically similar to those admitted initially to a ward. There was a higher proportion of successful resuscitations among patients admitted to a CCU, but there was no significant difference in mortality in either age group between patients admitted to a CCU and a ward.     

Advanced Heart Block During Acute Myocardial Infarction Treated with an Electrode Pacing Catheter

The mortality rate is high from advanced atrioventricular block associated with acute myocardial infarction. There is reason to believe that if in these patients the hearts are electrically paced with an endocardial pacing catheter, the mortality rate can be considerably decreased. Five patients in second- and third-degree heart block associated with acute myocardial infarction were paced with a considerable lowering of the expected mortality rate. Twenty-three cases from the literature are also presented and discussed. A silastic bipolar electrode catheter was used in these five cases. Four of the five cases returned to normal sinus rhythm within the first 10 days. The average duration of pacing was 6.7 days. It is the opinion of the author that second- and third-degree heart block associated with acute myocardial infarction should have a pacing catheter introduced at the earliest possible moment for continuous or demand endocardial pacing.