Discharge from a coronary care unit: psychological factors.

Anxiety is commonly experienced by patients following myocardial infarction. The role of anxiety in the recovery/rehabilitation process is not well understood, but anxiety is thought to be one of the factors determining outcome. It is important, therefore, to understand the possible effects on anxiety of changing discharge policies in coronary care units. Anxiety was assessed in a sample of MI patients, with good or poor prognoses, assigned to either early or late discharge from a coronary care unit. Although the overall level of anxiety of the total sample was not unduly high, it was clear that there was a subgroup of individuals, high in trait anxiety and with a poor prognosis, for whom early discharge was contra-indicated. Irrespective of prognosis, it was clear that early discharge did not produce a uniform response, indicating the need to differentiate between patients when determining the optimal date for discharge.

Incidence, delay and survival in the Belfast MONICA Project coronary event register.

During the 1983-85 period, the Belfast MONICA Project registered coronary events in 2,512 individuals (1,913 men and 599 women). The attack rates in men and women per 1,000 person years were 5.9 and 1.7 respectively, and the corresponding mortality rates were 2.4 and 0.61; both rates were heavily age-dependent. There were statistically significant differences in the age and sex-standardised rates for the 107 electoral wards of the Study. The median delay time from onset to delivery of care was 2 hours 30 minutes and 3 hours 2 minutes for men and women, respectively. Delays were shorter in younger and married individuals, and in those with previous infarctions. Unmarried individuals and those with chronic ischaemic heart disease were at significantly increased risk of pre-care death. Sixty per cent of deaths within 28 days of onset occurred before the patient could be admitted to hospital. Sixty-four per cent of males and 67% of females were alive at 28 days. Manual workers and their spouses had a poorer survival at 28 days. Married men and women were at lowest risk of death in the first 28 days, and this could not be attributed to the effects of age.

Myocardial infarction: hospital and home management in Northern Ireland.

Some 262 general practitioners in the Belfast area were asked to complete a questionnaire about their attitudes and practice regarding the management of myocardial infarction at home. Of the 211 responders, only nine per cent would sometimes consider home care for patients under 65 years of age, although 55 per cent would sometimes consider home care for those over 65 years and three per cent preferred home management for this age group. In the year preceding this study, seven per cent of these general practitioners treated only 22 myocardial infarction patients under 65 years of age at home (two per cent of all cases in the area). Home care for myocardial infarction patients appears to be less popular in Belfast than in other parts of the United Kingdom. The views of the general practitioners concerning home care are discussed.

Very early intervention with metoprolol in suspected acute myocardial infarction.

A double blind randomized study of 800 patients was carried out to determine if very early intervention with metoprolol (15 mg I.V. followed by oral administration) in suspected acute myocardial infarction affected overall mortality in selected subgroups, (age, site of infarct, delay to intervention). Sudden death occurred less frequently in patients allocated to metoprolol but there was no significant difference in total mortality on discharge, at three months and at twelve months. Ventricular fibrillation after intervention was not significantly reduced. Adverse reactions did not occur significantly more frequently in patients assigned to metoprolol.

Effect of very early intervention with metoprolol on myocardial infarct size.

All patients with a presumptive diagnosis of myocardial infarction, who were seen within six hours of the onset of symptoms and had no reason for exclusion, were considered for entry into a trial to compare the effects of metoprolol and placebo on creatine kinase MB isoenzyme release. The trial was randomised and double blind. The median time from onset of symptoms to receiving trial drug was just under two hours. Two hundred and four patients (of whom 120 had myocardial infarction) received metoprolol and 187 (of whom 105 had myocardial infarction) received placebo. Infarct size was estimated semiquantitatively using cumulative release of the cardiospecific isoenzyme, creatine kinase MB. Mean creatine kinase MB isoenzyme was less in patients who received metoprolol, but the reduction did not achieve statistical significance. Clinical problems related to early intravenous metoprolol were uncommon.

Comparison of the plasma concentrations and efficacy of mexiletine and of a slow-release preparation of mexiletine in patients admitted to a coronary care unit.

We determined if therapeutic plasma concentrations of mexiletine (0.75-2.0 microgram/ml) could be maintained in patients admitted to a coronary care unit by twice daily dosing of a new slow-release (S.R.) formulation of mexiletine. Twenty patients, 14 with acute myocardial infarction, entered the first study and received either 250 mg conventional mexiletine at 0.8, and 14 h or 360 mg S.R. mexiletine at 0 and 12 h each day for 7 days. Blood samples were taken daily for measurement of plasma mexiletine concentrations. A continuous 24 -h ECG recording was obtained in all patients between days 3 and 6. The mean plasma concentration was greater on all days in the group that received conventional mexiletine; these differences were most marked during the first 15 h on day 1. The mean trough values on days 2-7 were in the range 0.73-1.22 microgram/ml after mexiletine and 0.63-1.17 microgram/ml after S.R. mexiletine. The incidence of ventricular arrhythmias was the same in the two groups; side effects were less common in the group receiving S.R mexiletine. Since the plasma concentration increased slowly during day 1 with S.R. mexiletine, a second study was carried out in 19 similar patients who received 360 mg S.R. mexiletine, 720 mg S.R. mexiletine, or 360 mg S.R. mexiletine and 250 mg conventional mexiletine and 12 h later 360 mg S.R. mexiletine. The plasma concentration increased most rapidly after the third regime, reaching 0.97 +/- 0.09 microgram/ml at 3 hours. These results show that therapeutic plasma concentrations of mexiletine can be maintained by the 12-hourly administration of 360 mg S.R. mexiletine, but that an additional loading dose of 250 mg mexiletine increases the plasma concentration more rapidly.

Diagnosis of myocardial infarction from serum creatine kinase MB isoenzyme (CKMB) measurement.

The cardiospecific isoenzyme MB of creatine kinase (CKMB) has previously been shown to be of value in the diagnosis of myocardial infarction (MI). We studied 418 admissions to a coronary care unit (CCU) with suspected MI and calculated the sensitivity, specificity and positive and negative predictive values for several CKMB test functions. Several functions performed better than any combination of the other enzymes in common use. 97% of patients achieving a CKMB activity of at least 15 U/l did so between 6 and 30 h following the onset of symptoms. The present study confirms that the use of the CKMB isoenzyme leads to an earlier and more accurate diagnosis or exclusion of MI compared to the "cardiac enzyme series". The timing of blood sampling for CKMB estimation is also discussed.