Prediction of cardiovascular deaths and non-fatal reinfarctions after myocardial infarction

Methodological aspects in the design of secondary prevention trials

The aim of a secondary preventive trial is to produce results that may serve as a basis for therapeutic recommendations to other patients. The natural history of a disease studied including the mortality and reinfarction rate must be known and taken into consideration. The patients should be recruited without selection. By comparing the placebo mortality with expected levels the representativeness of patients can be assessed. One type of treatment can be expected to give different results in different groups of patients with the same disease, thus, prognostic prospective stratification may increase the value of comparisons and conclusions. The registration of end-points should preferably be done by a separate independent organization. Carefully classified specific mortality may be used as a major end-point in addition to total mortality. Similarly, different modes of deaths, e.g. sudden death, may be used if reliable definitions are used. Confounding factors are often difficult to isolate and identify and may have profound effects on the interpretation of a study. In all studies it is mandatory that the patient characteristics on entry do not differ between the different treatment groups. Concomitant treatment should be administered according to standardized criteria. The drop-out rate should be kept at a minimum. The possibility of generalization decreases with increasing drop-out rate. If the follow-up time becomes too long it is likely that at some time the relative benefit becomes less. Since the proportion of non-cardiovascular deaths increases with follow-up and age it may be critical to decide on the relevant follow-up time.

Acute myocardial infarction in diabetic patients

All patients hospitalized during a 3-year period with an acute myocardial infarction were followed for the occurrence of reinfarction or death. The patients with diabetes mellitus (n = 95) were compared with the non-diabetic population (n = 545). The diabetics had a higher mortality rate (relative death rate of 1.44 vs. 0.93, p less than 0.01) and a higher frequency of reinfarctions (18.9 vs. 10.8%, p = 0.04) than the non-diabetic population. A larger proportion of the diabetics had suffered a previous infarction, but the excess mortality was also present in those without a previous infarction. Established risk factors for death after myocardial infarction, such as age, infarct size, infarct localization and heart size, could not account for the difference in mortality. It is suggested that the increased mortality among the diabetics may be due to an increase in the rate of progression of the atherosclerotic heart disease.

Clinical features in patients with recurrent myocardial infarction

A retrospective investigation of 420 patients who had survived the acute phase of myocardial infarction revealed 63 reinfarctions (in 57 patients) within three months. Twenty-eight patients died without reinfarction during the same period, and 335 survived three months without reinfarction. The reinfarction patients were significantly more often women, had more frequently a history of previous myocardial infarction and hypertension, and their myocardial infarctions were more often non-transmural and localized to the anterior wall of the heart. The ECG of each patient that was registered nearest prior to the reinfarction during hospitalization or prior to discharge showed more often negative T-waves.

Predicting long-term mortality after a myocardial infarction from routine hospital data

Among 528 patients under 67 years of age discharged alive after a myocardial infarction (MI), the cumulative survival rates after 3, 5, and 7 years were 84.1%, 75.9% and 68.6%, respectively. Compared with the "normal" population, the relative mortality risk was 4.8 for the first year, 3.1 for the second, and on average 2.1 for the next 5 years. Significant age differences were not observed for relative mortality. A multivariate Cox proportional hazards model showed long-term mortality to be independently related to higher age, a reduced working activity before the MI, previous cardiovascular disease, and a higher inhospital complication score, which was computed by summing eight defined clinical events weighted for severity. The results indicate that a reasonable prediction of long-term survival after a MI can be made from routine hospital data.

Relationship between the enzymatically estimated infarct size and clinical findings in acute myocardial infarction

In 580 patients with a definite myocardial infarction (MI) and no previous MI, the enzymatically estimated infarct size was related to the clinical course including various complications. In all patients, heat-stable lactate dehydrogenase activity (EC 1.1.1.27, LD) was analyzed every 12 hours for 48-108 hours and in a subgroup (n = 170) creatine kinase activity (EC 2.7.3.2, CK) and creatinine kinase subunit B (CK B) were analyzed every 6 hours for 48 hours. The highest recorded enzyme activity was used as a rough estimate of infarct size. A positive correlation was found between serum enzyme activity and most of the clinical variables studied, such as incidence of congestive heart failure, treatment with furosemide, incidence of hypotension, cardiogenic shock, pericarditis, post myocardial infarction syndrome, AV block III, and the duration of hospitalization. We conclude that the enzymatically estimated infarct size determined by heat-stable LD, CK and CK B closely reflects the severity of the infarction.

Changes in heart size during long-term timolol treatment after myocardial infarction

The effect of long-term timolol treatment on heart size after myocardial infarction was evaluated by X-ray in a double-blind study including 241 patients (placebo 126, timolol 115). The follow-up period was 12 months. The timolol-treated patients showed a small but significant increase in heart size from baseline in contrast to a decrease in the placebo group. These differences may be caused by timolol-induced bradycardia and a compensatory increase in end-diastolic volume. The timolol-related increase in heart size was observed only in patients with normal and borderline heart size. In patients with cardiomegaly, the increase in heart size was similar in both groups. After re-infarction, heart size increased in the placebo group and remained unchanged in the timolol group.

Cost-benefit aspects of post-myocardial infarction intervention

After myocardial infarction the mortality during the first post hospital year declines from approximately 10 per cent to 5 per cent during the second year. The rates of non-fatal recurrencies are similar. Mortality is related to age but not to the same extent to sex. Non-fatal recurrencies are, however, not related to age. Prediction of mortality is feasible by several prognostic models. Factors related to size of myocardial damage stand out as the important secondary risk factors for the years immediately after infarction. Most of these factors are not generally related to risk of non-fatal recurrencies. The proportion of cardiovascular deaths is 90 per cent during the first years and declines thereafter. Simplistically it may be said that the prognosis during the first years is related to the extent of the myocardial damage and thereafter primary risk factors become more important. Thus, it seems logical in the short-term perspective to influence myocardial factors and related arrhythmias and in the long-term perspective to influence primary risk factors which more likely operate on the vascular factors. Three preventive methods have demonstrated a positive benefit: 1) chronic beta-blockade, 2) cessation of smoking, 3) by-pass surgery in certain categories. After careful calculations it may be argued that at least half of the total mortality may be inhibited by beta-blockade and cessation of smoking. The impact of coronary surgery, lipid lowering and reduction of high blood pressures is more difficult to assess.

The prognosis for patients referred with suspected acute myocardial infarction

A follow-up investigation of the prognosis of 381 patients admitted with suspected acute myocardial infarction (AMI) has been carried out in respect of later AMI or death. During hospitalization the patients were divided into groups with particular attention to patients with no demonstrable myocardial infarction but with ischaemic heart disease (non-AMI) and patients with confirmed AMI. All patients were subjected to follow-up for 43 months (range 37-54). The mortality from cardiovascular causes after four years was 26.2% of 130 non-AMI patients and 25.8% of AMI patients. The majority of new infarctions were found in the AMI patients, but with even increase in both groups, 50% occurring within the first 12 months. The groups were studied with regard to earlier manifestations of ischaemic heart disease and heart failure during hospitalization, without any difference being observed. Due to the poor prognosis the question is raised whether non-AMI patients as a group should be offered prophylactic therapy.

T wave changes after acute myocardial infarction predicting reinfarction

Of 420 consecutive patients with acute myocardial infarction who survived the coronary care unit period, 57 developed 63 reinfarctions with 16 deaths within three months (reinfarction group). Of the remaining 363 patients, 28 died without evidence of reinfarction during the same observation period and 335 survived. The last ECGs before discharge, or prior to a reinfarction in hospital, of the reinfarction patients were studied and compared with time-matched ECGs from the 335 survivors without reinfarction. In ECGs without interfering patterns, the slope of the ascending limb of a negative T wave was measured as the angle to the vertical plane (interobserver variation less than or equal to 5 degrees in 95%). Of the 63 reinfarctions, 40% had a steeply ascending limb of a negative T wave (T wave angle less than or equal to 55 degrees in lead II, less than or equal to 35 degrees in CR4 and/or less than or equal to 40 degrees in CR7) and a QRS complex without signs of infarction in the same lead (abnormal Q waves or abnormal R wave progression). The same criteria were fulfilled by 6% of the 335 survivors without reinfarction (p less than 0.001) and by one of the 28 patients who died without reinfarction. Thus, a steeply ascending limb of a negative T wave in the acute phase of a myocardial infarction heralds a reinfarction if the QRS complex of the same lead does not show signs of infarction (3-month sensitivity 40% and predictive value 53%). A T wave angle less than or equal to 35 degrees in CR4 corresponds to less than or equal to 40 degrees in V4. CR7 is not transferable to V6 but was the least predictive lead.

Effect of timolol on late ventricular arrhythmias after acute myocardial infarction

This is a subproject of the Norwegian timolol myocardial infarction study carried out at one of the clinical centers. High risk patients surviving either a reinfarction or large initial infarction were randomized to placebo (44 pts) or timolol (37 pts). A 24 hour ECG was obtained the day before randomization (at baseline, 7-28 days after the acute attack) then 3 days, 1 month and 6 months after start of therapy. During this period the number of patients with one or more of ventricular couplets, bigemini, ventricular tachycardia or early cycle premature ventricular contractions (PVC) (i.e. complex ventricular arrhythmias) and the average number of PVC per hour increased significantly in the placebo group but not in the timolol group. The results indicate that there is an increased severity and incidence of ventricular arrhythmias in the first 6 months after myocardial infarction. Timolol effectively inhibited this trend. The importance of timolol as an antiarrhythmic agent may therefore be to prevent subclinical infarction extension and secondary ventricular arrhythmias related to the size of the myocardial damage.

Relationship between enzymatically estimated infarct size and short- and long-term survival after acute myocardial infarction

In 585 patients with acute myocardial infarction (AMI) and no previous MI the maximal activity of serum heat-stable lactate dehydrogenase (LD) (EC 1.1.1.27) activity was related to 1-year and 2-year mortality rates. All patients participated in a double-blind trial with metoprolol during the first three months after an AMI. Thereafter both groups were treated in a similar way. A strong relationship was found between LD maximum activity and the in-hospital prognosis (p less than 0.001), the 1-year survival rate (p less than 0.001) and the 2-year survival rate (p less than 0.001). When the patients who were alive after primary hospitalization were analyzed as a separate group, the relationship between LD maximum activity and 1-year and 2-year survival rates remained (p less than 0.001). In a subsample of 171 patients the maximal activity of creatine kinase (CK) (EC 2.7.3.2) and CK subunit B did not correlate either with in-hospital, 1-year or 2-year survival rates. We conclude that, when a sufficiently large number of patients are investigated, there is a strong relationship between serum enzyme maximum activity and short- and long-term survival.

Early and sudden deaths after myocardial infarction. A report from the Swedish CCU study

1329 patients were discharged alive after acute myocardial infarction initially treated in a CCU. In a five-year follow-up, 537 (40%) of the patients died. Routine data registered uniformly during the CCU period showed that, apart from age, the most important factors regarding long-term prognosis in general were previous ischaemic heart disease and direct or indirect signs of heart failure registered in the CCU. The possibilities to predict sudden death (130 patients died within 2 hours of onset of final symptoms during the follow-up period) were small, although a definite dominance of this mode of death was noted in patients below 60 years of age. The clinical profile of the majority of the 134 patients who died during the first half-year was distinguished by a history of prior myocardial infarction and signs of left heart failure during the CCU stay. However, in a significant number of patients dying early after discharge, none of the ordinary unfavourable prognostic signs had been registered.

Influence of a myocardial infarction on blood pressure and serum cholesterol

Blood pressure (BP) was measured before and after acute myocardial infarction (MI) in 21 men aged 49--60 years from a random population sample. Men on drugs affecting BP before MI or during follow-up were excluded. Pre- and postinfarction cholesterol levels were analyzed in 49 men not on hyperlipidemic treatment recruited from the same population sample. The mean fall in systolic BP (SBP) was 14 mmHg both five weeks and one year after the acute event, but 10 mmHg after two years. The mean fall in diastolic BP (DBP) was 10 mmHg five weeks after the MI and remained at this level for two years. The decreases in SBP and DBP were significant. There was a positive correlation between the maximum rise in SGOT during the acute phase of MI and the decrease in DBP between preinfarction readings and readings five weeks after the MI. Serum cholesterol was unchanged three months, and one and two years after the MI as compared to the preinfarction level.

A controlled study of early discharge after uncomplicated myocardial infarction

Out of 383 myocardial infarction (MI) patients aged below 70 years, 252 (66%) were judged after the third day in hospital to have had uncomplicated infarctions. These patients were allocated at random to two groups, one of which was given treatment for 8 days and the other for 15 days. No significant differences in mortality, morbidity or incapacity for work could be detected during the three-month period of follow-up. The findings thus support previous conclusions that early discharge from hospital after uncomplicated MI is not associated with greater risk for the patient than later discharge.

Reappraisal of the importance of heart rate as a risk factor for cardiovascular morbidity and mortality

Heart rate is a key determinant of myocardial oxygen consumption. Several lines of evidence support a consistent association between heart rate and cardiovascular mortality. Increments in heart rate are positively related to cardiovascular and sudden death in patients with hypertension or previous myocardial infarction and in the elderly with heart disease. This relationship is important because a number of commonly used cardiovascular agents, such as beta-blockers and calcium antagonists (CAs), can affect heart rate. Beta-blockers decrease heart rate and reduce morbidity and mortality in post-myocardial infarction patients. The CAs are a structurally diverse group of agents with different physiologic effects. The dihydropyridine CAs are not associated with a reduction in heart rate. In fact, often they can cause reflex tachycardia as a result of potent systemic vasodilator action, which may provoke angina, especially in patients with ischemic heart disease. The nondihydropyridine CAs verapamil and diltiazem reduce heart rate but are associated with negative inotropy. Mibefradil, the first member of a new class of CAs, reduces heart rate and is not associated with negative inotropic effects. This unique pharmacologic profile may be of great value in treating hypertensive patients, particularly those with coexisting ischemic heart disease, and also patients with angina pectoris alone. However, the clinical benefit of pharmacologically reducing heart rate with mibefradil needs to be demonstrated in controlled trials.

Predictors of nonfatal reinfarction in survivors of myocardial infarction after thrombolysis. Results of the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico (GISSI-2) Data Base

OBJECTIVES

This study was designed to reassess the prediction of recurrent nonfatal myocardial infarction in patients recovering from acute myocardial infarction after thrombolysis.

BACKGROUND

Recurrent nonfatal myocardial infarction is a strong and independent predictor of subsequent mortality. Current knowledge of risk factors for nonfatal reinfarction is still largely based on data gathered before the advent of thrombolysis. Thus, this prospective study was planned to identify harbinger of nonfatal reinfarction in the postinfarction patients of the multicenter Grouppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico (GISSI-2) trial.

METHODS

Predictors of nonfatal reinfarction at 6 months were analyzed by multivariate technique (Cox model) in 8,907 GISSI-2 survivors of myocardial infarction with clinical follow-up, relying on a set of prespecified variables reflecting residual ischemia, left ventricular failure or dysfunction, complex ventricular arrhythmias, comorbidity as well as demographic and historical factors.

RESULTS

The postdischarge to 6-month incidence rate of nonfatal reinfarction was 2.5%. Independent predictors of nonfatal reinfarction were cardiac ineligibility for exercise test (relative risk 2.97, 95% confidence interval [CI] 1.98 to 4.45), previous myocardial infarction (relative risk 1.70, 95% CI 1.22 to 2.36) and angina at follow-up (relative risk 1.50, 95% CI 1.10 to 2.04). On further multivariate analysis, performed in 6,580 patients with both echocardiographic and electrocardiographic monitoring data available, a history of angina emerged as an additional risk predictor (relative risk 1.58, 95% CI 1.10 to 2.25).

CONCLUSIONS

The 6-month incidence of nonfatal reinfarction is rather low in survivors of myocardial infarction after thrombolysis. Cardiac ineligibility for exercise testing and a history of coronary artery disease are risk predictors. Recurrent nonfatal infarction is not predictable by qualitative variables reflecting residual ischemia, except by postdischarge angina. Prediction of nonfatal reinfarction appears less accurate than prediction of mortality, as almost 50% of reinfarctions occur in patients without any of the identified risk factors.

Dynamics of the QT interval in patients with exercise-induced ventricular tachycardia in normal and abnormal hearts

Inhomogeneity of ventricular repolarization reflected in prolongation of the QT interval of the surface electrocardiogram can predispose patients to ventricular arrhythmia. This study examines whether an abnormality of QT adaptation to changes in heart rate is likely to be of importance in the pathogenesis of ventricular tachycardia (VT) in patients with and without underlying structural heart disease. The QT-R-R relationship during exercise was studied in 52 patients. Forty-two patients had VT associated with a "clinically normal" heart (idiopathic VT), of which 23 had no VT on exercise and 19 had exercise-induced VT. These patients were compared to 10 subjects with exercise-induced VT related to ischemic heart disease. The QT interval was measured manually from computer-averaged QRS complexes recorded at 1- to 3-minute intervals during treadmill exercise tests. An approximately linear association existed between the QT and R-R intervals within the range of heart rates observed. The slope of the QT-R-R relation was lower in patients with structural heart disease (0.23 +/- 0.06) than in patients with normal hearts with (0.29 +/- 0.12) and without (0.29 +/- 0.12) exercise-induced VT (p < 0.05). The intercept of the regression line was higher in patients with structurally abnormal hearts (209.2 +/- 55.3 msec) than in patients with idiopathic VT with (155.6 +/- 49.7 msec) and without (157.7 +/- 69.0 msec) exercise-induced VT (p < 0.02). The corrected QT (Bazett's formula) was similar all three groups at rest, but was higher in patients with structurally abnormal hearts at peak exercise, 449.6 +/- 28.0 versus 425.8 +/- 27.4 msec (idiopathic VT, exercise induced) versus 427.3 +/- 26.6 msec (idiopathic VT, not exercise induced) (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Diuretics in postinfarction heart failure

Severe left ventricular failure, as evidenced by radiographic pulmonary edema or raised left ventricular filling pressure, accompanying acute myocardial infarction, carries a high mortality risk. In this situation, the intravenous loop-diuretic furosemide induces a rapid reduction in the raised left ventricular filling pressure due to an immediate and substantial increase in systemic venous compliance accompanied by increasing diuresis. This diuretic-induced venodilatation is probably due to the release of prostaglandins. The transient systemic arterial constriction and small increase in systemic blood pressure that follows intravenous furosemide probably results from the release of renin and subsequent activation of angiotensin. These diuretic induced hemodynamic changes are accompanied by restoration of the vasodilator reflex, which enables the heart to accommodate an acute volume load. Orally administered loop diuretics achieve slower, but similar, directional hemodynamic changes. There is no information on hemodynamic or neuroendocrine dose-response effects of loop diuretics, and there is no information pertaining to the use of other diuretic groups in this situation. The hemodynamic changes induced by furosemide summate with the changes induced by other anti-heart-failure drugs. In this subset of patients with acute myocardial infarction and severe heart failure, the influence of the diuretics on morbidity incidence and mortality risk remains to be measured.

Predictors and long-term prognostic significance of recurrent infarction in the year after a first myocardial infarction. SPRINT Study Group

This study was undertaken to examine whether clinical factors predict reinfarction within 1 year of a first acute myocardial infarction (AMI) and to quantify the subsequent influence of reinfarction on long-term mortality. Data from 3,695 patients with a first AMI included in the Secondary Prevention Reinfarction Israeli Nifedipine Trial Registry were analyzed. The 1-year reinfarction incidence was 6.0% (220 of 3,695) and in-hospital mortality during reinfarction was 31%. Patients with reinfarction were older (63.0 vs 60.8 years) at entry. The independent clinical predictors for 1-year reinfarction were (adjusted relative odds): peripheral vascular disease (2.12), anterior location of the first AMI (1.62), angina before the first AMI (1.53), congestive heart failure on admission (1.34), diabetes (1.33), systemic hypertension (1.28) and age increment (1.13). One-year reinfarction rate increased from 4.0% in patients with 0 or 1 risk factor to 23.3% in patients with 5 to 6 risk factors (p < 0.0001). Patients with reinfarction had significantly increased 1- and 5-year mortality compared with those who had no reinfarction (11.8 vs 5.3% and 40.1 vs 20.3%, respectively, p < 0.001). Recurrent AMI within 1 year was the most powerful predictor of long-term (mean 5.5 years) total mortality (adjusted relative risk = 4.76).

Effects of beta blockers on ventricular dysfunction after myocardial infarction: tolerability and survival effects

At least 44 randomized trials of beta blockade in acute myocardial infarction have been reported. All of these trials excluded patients with moderate-to-severe clinical signs of acute left ventricular dysfunction (LVD). Several of the larger trials did include high-risk patients with a history of compensated heart failure or with symptoms and signs suggesting mild LVD. Data from these trials indicate that beta-blocker treatment was well tolerated by patients with LVD, both in the acute phase of myocardial infarction and during long-term follow-up treatment. Further, data for LVD patients indicate that mortality in the beta-blocker group was reduced by 20-30% when compared with the placebo group. A similar mortality reduction was obtained for the entire patient population in the trials. Because of the high mortality among patients with mild LVD, the absolute gain in numbers of lives saved per 100 patients treated with beta blockers is even larger than that in patients without LVD. Data from two long-term trials indicate marked (47% and 43%) reductions in the likelihood of sudden death among LVD patients treated with beta blockers. These results suggest that all patients with LVD who can tolerate beta blockade may benefit from treatment with these agents.

Mode of QT correction for heart rate: implications for the detection of inhomogeneous repolarization after myocardial infarction

In 22 conscious, chronically instrumented dogs, the relationship between R-R interval and QT interval was better explained by linear regression than by nonlinear regression according to Bazett's formula. The correction formula QTL = QT-0.1*(RR-1000), which is based on the assumption of a linear relationship between QT and R-R interval, was then compared with Bazett's formula regarding its capability to detect inhomogeneous repolarization 5 to 7 days after temporary occlusion of the left anterior descending coronary artery. This comparison was performed only in those dogs exhibiting changes in QRS duration of less than 5 msec in response to myocardial infarction (n = 12). In these animals, myocardial infarction resulted in a significant dispersion of repolarization between the left ventricular normal zone and the infarct zone and a shift to the right of strength-interval curves of the infarct zone with respect to the normal zone, indicating local dispersion of refractoriness. As opposed to QTc (Bazett's formula), QTL was significantly (p = 0.04) prolonged after occlusion. Hence the adequacy of QT correction contributes significantly to the detection of inhomogeneous ventricular recovery after acute myocardial infarction.

Factors associated with recurrent myocardial infarction within one year after acute myocardial infarction

In a large population of patients (n = 3666) who were discharged from the hospital after acute myocardial infarction and followed up for 1 year, factors associated with recurrent nonfatal (n = 171) or fatal (n = 74) infarction were identified. Also, the effects of combining various end points (recurrent nonfatal or fatal infarction and other cardiac death) in multivariate analyses, a practice common in many small studies that evaluate the predictive-value of various treatments or special tests, was examined. In univariate analyses, patients with nonfatal recurrent infarction did not differ with respect to age or gender from infarct-free survivors, but they more often had a history of previous myocardial infarction, congestive heart failure, angina pectoris, and diabetes; more severe pulmonary congestion was present on chest x-ray during the admission, and a non-Q wave index infarction was more frequent. Patients with either a fatal or nonfatal recurrent infarction had more angina pectoris during follow-up (55% to 60%) compared with 27% in event-free survivors and 31% in patients who died of other cardiac causes in whom this factor could be assessed before death. In multivariate analyses, historical and clinical prognostic factors were ranked differently for fatal or nonfatal reinfarction and other cardiac causes of death; angina pectoris at follow-up was highly related to recurrent infarction (fatal or nonfatal), along with a history of diabetes, and a non-Q wave index infarction. These factors were not independently related to other causes of cardiac death.(ABSTRACT TRUNCATED AT 250 WORDS)

Impact of atrial fibrillation on the in-hospital and long-term survival of patients with acute myocardial infarction: a community-wide perspective

As part of an ongoing community-wide study examining changes over time in the incidence and survival rates of 4108 patients hospitalized with validated acute myocardial infarction (MI) in 16 hospitals in the Worcester, Massachusetts, metropolitan area during calendar years 1975, 1978, 1981, 1984, and 1986, we examined changes over time in the proportion of patients with acute MI developing atrial fibrillation (AF) and the impact of AF on in-hospital and long-term survival for up to a 10-year follow-up period. The overall percentage of patients with AF complicating acute MI was 16.0%; this proportion increased over time from 13.3% in 1975 to 14.8% in 1978, 14.9% in 1981, 20.3% in 1984, and to 17.7% in 1986. Patients with AF experienced consistently higher in-hospital case fatality rates than MI patients without AF overall (27.6% versus 16.6%), as well as during each of the 5 years under study. The independent effect of AF on in-hospital survival was not upheld, however, when a variety of potentially confounding prognostic factors were controlled for in a multivariate analysis resulting in an adjusted odds ratio (OR) of 1.18 (95% confidence interval 0.90, 1.52). Among discharged hospital patients, while the crude long-term survival rate for patients with AF was poorer than that of patients without AF for the combined as well as for individual study periods, similar to the in-hospital findings the independent effect of AF on long-term prognosis was not upheld after use of a multivariate analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Prediction of mortality after myocardial infarction by simple clinical variables recorded during hospitalization

Simple clinical variables obtainable in any coronary care unit and in any patient were recorded in 769 consecutive patients who were admitted with acute myocardial infarction (AMI) and who were discharged from the hospital and followed for up to 3 years. To identify the patients at highest and lowest risk of posthospital mortality, a prognostic index was established from a stepwise logistic discriminant analysis of variables obtained in a consecutive series of 418 patients discharged alive from one of two coronary care units admitting new patients on alternate days. This prognostic index was validated by applying it to a comparison group of 351 consecutive control patients discharged from the other coronary care unit. In the training group, 59 of the 418 patients (14%) died during the first year after hospital discharge and 34 (8%) died during the second or third year. The stepwise logistic discriminant analysis made it possible to distinguish between 1-year survivors and nonsurvivors, but not between the patients who died during the second and third years and the 3-year survivors. Four variables were selected for obtaining a 1-year prognostic index: the maximum grade of left ventricular function during hospitalization (0 to 4), history of previous AMI (1 or 0), predischarge cardiothoracic ratio (0 to 0.99), and complete bundle branch block (1 or 0). Prognostic index = 7.0196-0.6515 function - 1.6623 previous AMI - 0.0729 cardiothoracic ratio - 1.0813 bundle branch block. This index was validated in the comparison group.(ABSTRACT TRUNCATED AT 250 WORDS)

The relationship between serum enzyme activity, infarct site, and cardiac complications after a first myocardial infarction. A follow-up study in general practice

The aim of the present study was to relate the clinical course in patients after a first acute myocardial infarction with the site and size of infarct, estimated from standard enzyme measurements. One hundred and eight consecutive patients who suffered an acute myocardial infarction for the first time were followed-up after 30 months in general practice. Twenty-six patients had died and 8 had had another infarction. Sixty-two of the surviving patients had received treatment for ischaemic heart disease, usually for angina pectoris and less often for heart failure and arrhythmias. No correlation was found between ischaemic heart disease requiring treatment and the enzyme-estimated size or the site of the infarct. With anterior infarcts there was, however, an overweight of arrhythmias requiring treatment. Of the patients at work, 31% had changed job or job status because of ischaemic heart disease. At the end of the 30 month period, 50 patients were in functional class 1 and 2, and 32 in functional class 3 and 4 (New York Heart Association's classification).

Do X-ray determined cardiac volume and signs of congestive heart failure provide additional prognostic information after myocardial infarction if the left ventricular ejection fraction is known?

Cardiac volume (CV) was measured and indices of pulmonary congestion (PCG) were judged from routine chest films taken post myocardial infarction (AMI) in a consecutive series of 477 patients (340 first and 137 recurrent AMIs). Cardiac volume (CV) and signs of PCG were compared to left ventricular ejection fraction (LVEF), measured with isotope technique, and the prognostic value of all the parameters was assessed after 1 and 5 years. The accuracy of CV and PCG in predicting impaired LVEF was low (62% and 50% respectively). Although specificity is suboptimal, however, these parameters provided valuable prognostic information. For example, patients with signs of PCG had a very high 1 and 5 years' mortality, and two-thirds of those who died during the first year of observation had enlarged CV. The independent value of LVEF determination was mainly observed in re-AMI patients. A more restricted use of this expensive procedure may therefore be recommended.

Morbidity during five years after myocardial infarction and its relation to infarct size

In 809 patients with a recent myocardial infarction, morbidity during 5-year follow-up was assessed. The overall 5-year mortality rate was 33% (39% in patients with larger infarcts and 26% in patients with smaller infarcts) as judged from maximum serum enzyme activity (p less than .001). In terms of morbidity, no significant association with estimated infarct size was observed. Patients with smaller infarcts tended to have a higher reinfarction rate and were rehospitalized more often, whereas a similar proportion of patients with large and small infarcts developed stroke. Among survivors, chest pain tended to be more common in patients having smaller infarcts, whereas symptoms of dyspnea and claudicatio intermittens were similar in both groups, as were smoking habits, work capability, and varying forms of medication. We thus conclude that during a 5-year follow-up after acute myocardial infarction, mortality, but not morbidity, was related to the original infarct size.

Factors of importance for prognosis in men with angina pectoris derived from a random population sample. The Multifactor Primary Prevention Trial, Gothenburg, Sweden

A random population sample of middle-aged men from the Primary Prevention Trial was followed for 11.3 years from a first screening when different factors known to be associated with coronary artery disease (CAD) were analyzed. Men with uncomplicated angina pectoris (AP) (n = 167) derived from this population had an incidence of fatal and nonfatal CAD events 3 times higher than that of men without AP or myocardial infarction (n = 5,774). Men with myocardial infarction with or without AP had an incidence of CAD events 7 to 8 times higher than that of men without AP or myocardial infarction. Similar differences were found for new cases of uncomplicated AP (n = 128) and myocardial infarction detected at a second screening after 4 years and followed for 7.3 years. Pooled data from this series of men with uncomplicated AP showed the following factors to be associated in multivariate analysis with nonfatal or fatal CAD endpoints during follow-up: elevated serum cholesterol, elevated blood pressure, smoking and attack score. The risk increase associated with the first 3 factors was similar to the general population. These findings indicate that the same factors affecting prognosis after a first appearance of AP affect similarly patients with myocardial infarction and clinically healthy subjects. Preventive measures against these risk factors seem to be of similar importance among patients with AP, post-infarct patients and healthy subjects.

Five-year mortality rate in relation to enzyme-estimated infarct size in acute myocardial infarction

In 727 patients with acute myocardial infarction, different enzyme variables reflecting infarct size were related to the 5-year mortality rate. The maximum activity of serum heat-stable lactate dehydrogenase (LD), analyzed every 12 hours for 48 to 108 hours, was significantly associated with the 5-year mortality rate when patients with a first myocardial infarction were evaluated (p less than 0.001), and similarly (p less than 0.001) when patients with a previous myocardial infarction were included in the analyses. Very similar results were found when the maximum activity of aspartate aminotransferase (ASAT) analyzed once daily for 3 days was related to the mortality rate over 5 years, whereas the maximum activity of creatine kinase (CK) and CK subunit B analyzed every 6 hours for 48 hours in a subset of patients did not predict the outcome to the same extent. The results from LD and ASAT analyses clearly indicated that the association between infarct size and 5-year mortality rate was caused by the much higher mortality rate in patients with larger infarcts during the first year after onset of infarction, whereas after the first year, incidence of death appeared to be independent of the original infarct size. Thus we conclude that although a highly significant relationship between infarct size and overall 5-year survival was found, the mortality rate seemed to be higher in patients with larger infarcts, particularly during the first year after infarction.

Limitations and advantages of the ejection fraction for defining high risk after acute myocardial infarction

Left ventricular (LV) ejection fraction (EF) is known to be related to prognosis after acute myocardial infarction (AMI), but its role alone and in combination with other factors in the definition of a high-risk group has not been adequately specified. Several recent multicenter studies emphasize that LVEF together with features of ventricular ectopic activity during ambulatory electrocardiography define a group at high risk for death for up to 3 years. However, these high-risk groups comprised only a small fraction of the population (less than 7.5%) and failed to include 75% or more (less than 25% specificity) of observed events. In our study, LVEF was determined close to the time of hospital discharge in 750 patients with AMI enrolled in a collaborative study. Used alone, an LVEF of less than 0.45 best defined a high-risk group (39% of the population) yielding 62% sensitivity and 64% specificity for total cardiac mortality by 1 year; it was 77% sensitive for sudden death alone. In a multivariate analysis together with other factors, LVEF was an independent predictor, but other markers of LV dysfunction entered before LVEF with similar sensitivity for total cardiac deaths, but with increased specificity (75%). When an LVEF of less than 0.45 was used together with the presence of complex arrhythmias to define a high-risk group (19% of the population), sensitivity decreased to 39% and specificity increased to 84%. Thus, LVEF is a simple and effective alternative to multivariate analysis for risk assessment after AMI.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of timolol on mortality and reinfarction after acute myocardial infarction: prognostic importance of heart rate at rest

Long-term timolol treatment after acute myocardial infarction is associated with a significant reduction in mortality and nonfatal reinfarction. To evaluate whether the reduction in mortality and morbidity is exclusively or partly dependent on a reduction in heart rate (HR), cardiac events in the Norwegian Timolol Multicenter Study were analyzed according to resting HR at baseline and at 1 month of follow-up Resting HR at baseline was a significant predictor of total death and all events (total death plus nonfatal reinfarction) both in placebo- and in timolol-treated patients. In the placebo group the median resting HR was unchanged from baseline to 1 month control (72 beats/min), but was reduced from 72 beats/min to 56 beats/min in the timolol group. Resting HR during follow-up remained a significant predictor of total death. Further, mortality at a given HR during treatment was not markedly different whether the HR was spontaneous or caused by timolol. Timolol treatment was related to a significant reduction in mortality, and this study suggests that the major effect of timolol treatment on mortality after acute myocardial infarction may be attributed to the reduction in HR. Timolol treatment was also associated with an overall reduction in nonfatal reinfarction. However, nonfatal reinfarction was inversely related to resting HR during follow-up, indicating that although coronary artery occlusion in low-risk patients may cause nonfatal reinfarction, the outcome in high-risk patients is more likely to be death. When analyzing mortality and nonfatal reinfarction combined, timolol treatment was related to a reduction in cardiac events at any given HR, suggesting that factors in addition to HR reduction are important in the protective effects of timolol.

Appearance of T-wave inversions without raised serum enzyme activity in suspected acute myocardial infarction: clinical outcome in relation to subendocardial infarction

In 67 patients with a clinical history of suspected acute myocardial infarction (MI) who developed T-wave inversions in standard ECG and had normal serum aspartate aminotransferase activity (possible MI) the clinical outcome was compared with that in patients fulfilling criteria for subendocardial infarction. Patients with possible MI had a lower mortality (p = 0.02) and also a lower reinfarction rate (p = 0.14) during the first 2 years as compared with those with subendocardial MI. Although patients with subendocardial MI had more problems with chest pain in the acute phase, angina pectoris occurred more frequently in patients with possible MI during a longer follow-up period. Congestive heart failure occurred more frequently in patients with subendocardial MI during initial hospitalization, whereas treatment for heart failure appeared similar in the two groups during a longer follow-up time. We conclude that the clinical course in patients with possible MI, here defined as chest pain and appearance of T-wave inversions without elevation of serum enzyme activity, seems to differ from that in patients with subendocardial MI, particularly regarding long-term survival and incidence of angina pectoris.

Sudden death and its relation to QT-interval prolongation after acute myocardial infarction: two-year follow-up

Risk of sudden death was assessed in 533 patients who survived 10 days after acute myocardial infarction (AMI) and were followed for up to 24 months (mean 18) in the Multicenter Investigation of the Limitation of Infarct Size. Analysis of clinical and laboratory variables measured before hospital discharge revealed that the QT interval, either corrected (QTc) or uncorrected for heart rate, did not contribute significantly to prediction of subsequent sudden death or total mortality. In this population, frequent ventricular premature complexes (more than 10 per hour) on ambulatory electrocardiographic monitoring and left ventricular (LV) dysfunction (radionuclide LV ejection fraction of 0.40 or less) identify patients at high risk of sudden death. In patients with these adverse clinical findings, the QTc was 0.468 +/- 0.044 second among those who died suddenly and 0.446 +/- 0.032 second in survivors, and was not statistically significant as an additional predictor of sudden death. Consideration of the use of type I antiarrhythmic agents, digoxin, presence of U waves and correction for intraventricular conduction delay did not alter these findings. Although QT-interval prolongation occurs in some patients after acute myocardial infarction, reduced LV ejection fraction and frequent ventricular premature complexes are the most important factors for predicting subsequent sudden death in this patient population.

The influence of early intervention in acute myocardial infarction on long-term mortality and morbidity as assessed in the Göteborg metoprolol trial

The mortality and morbidity were assessed during a 2-year follow-up in an acute intervention trial in suspected acute myocardial infarction with metoprolol (a selective beta 1-blocker). On admission to the trial, the 1395 participating patients were randomly allocated to metoprolol or placebo for 3 months. Thereafter, if there was no contraindication, patients with infarction and/or angina pectoris were continued on metoprolol for 2 years. A lower mortality was observed after 3 months in patients randomised to metoprolol. The difference remained after 2 years. The difference in 2-year mortality rate was restricted to patients randomised early after onset of pain. Late infarction was observed more often in the placebo group during the first 3 months. When the two groups thereafter were treated similarly, the difference successively declined and did not remain after 2 years. A similar incidence of angina pectoris was observed in the two groups at each check up. During the early recovery period, more patients in the metoprolol group returned to work. No such difference was observed later on.

Relationship between electrocardiographically estimated infarct size and morbidity during a two-year follow-up

In 587 patients with a first myocardial infarction (MI) the electrocardiographically (ECG) estimated infarct size was related to morbidity during a two-year follow-up. Patients with transmural MI (Q- or R-wave changes in standard ECG) were more often treated for heart failure and returned to work less frequently than patients with subendocardial MI (ST-T-wave changes only). There were trends indicating a higher reinfarction rate in patients with subendocardial MI, whereas angina pectoris was observed as frequently in both groups. In a subset of patients with anterior MI, infarct size was estimated from the total Q- and R-wave amplitude in 24 precordial leads 4 days after arrival in hospital. A positive relationship was observed between ECG-estimated infarct size and treatment for heart failure, and patients with smaller infarctions according to ECG criteria returned to work less frequently. A higher reinfarction rate was observed in patients with smaller infarctions. In patients with inferior MI there were mostly weaker correlations between ECG-estimated infarct size (Q- and R-wave changes in leads II, III, and a VF) and morbidity during the two-year follow-up.

The mortality predictive power of discharge electrocardiogram after first acute myocardial infarction

The prognostic value of discharge ECG was studied in 457 patients after their first acute myocardial infarction. Thirteen different ECG variables were studied on the discharge ECG. When cumulative 4-year survival rates were calculated by standard life-table method for each variable individually, the following variables had statistically significant prognostic power: PTF (P terminal force), PTFA (P terminal frontal axis), AF (atrial fibrillation), ST depression, ST elevation, QRS duration, and the combination block (LBBB/RBBB + LAHB/LPHB). The variables with no statistically significant predictive power were: QTc, LBBB or RBBB, LAHB or LPHB, AV block, T wave angle, T negativity, and sigma R. The relative risks for the most important variables in the discrete life-table model were: PTF 3.4, QRS duration 3.3, ST depression 2.6, PTFA 2.5, and ST elevation 2.2. In further analysis a model with only three ECG variables (PTF, ST depression, and ST elevation) was developed which stratified the study population in categories with 1.9% to 75.5% estimated 4-year survival rates.

Secondary prevention after myocardial infarction: subgroup analysis of patients at risk in the Norwegian Timolol Multicenter Study

Timolol treatment after myocardial infarction is generally related to a significant reduction in both mortality and reinfarction compared with placebo. Retrospective analyses of the timolol study are performed on subgroups of patients with a high placebo mortality. The present study shows that these patients are target groups for secondary prevention, as they benefit most from timolol treatment after myocardial infarction. In patients 65-75 years of age, the number of cardiac deaths and reinfarctions prevented by timolol treatment is twice as high as that of patients below 65 years of age. Timolol treatment is well tolerated in the older age group and the contraindications for timolol treatment are independent of age up to 75 years. The reduction in mortality and reinfarction is independent of heart size at baseline. However, in patients with cardiomegaly and compensated heart failure on treatment with digitalis and diuretics, timolol treatment may be of special importance because of the very high incidence of cardiac death in this group of patients. In patients with compensated heart failure on treatment with digitalis and diuretics, timolol treatment does not precipitate heart failure. Patients with stable diabetes mellitus basically behave like nondiabetic patients regarding inclusion rate, side effects, and timolol-related reduction in mortality and reinfarction. Decisions concerning secondary prevention with timolol should be independent of preinfarction and postinfarction angina. In conclusion, 70-80% of all the patients below 75 years of age surviving myocardial infarction, without contraindication to beta-blocker treatment, can be treated with timolol 10 mg twice daily to reduce mortality and reinfarction. In contrast to previous routines, secondary prevention with beta blockers should be especially directed to high-risk patients.

The relationship between the electrocardiographically estimated infarct size and 1- and 2-year survival in acute myocardial infarction

In 587 patients with acute myocardial infarction (AMI) and no previous MI, electrocardiographically estimated infarct size was related to 1- and 2-year mortality. The overall mortality was higher in patients with transmural MI (Q- or R-wave changes in standard ECG) than in patients with subendocardial infarction (ST-T-wave changes in standard ECG) after 1 year (18.8% compared to 6.5% p less than 0.001) and after 2 years (22.2% compared to 13.8%, p = 0.049). When patients who were alive during primary hospitalization were analyzed separately, slightly higher mortality was found in patients with transmural MI than in subendocardial MI after 1 year (9.6% compared to 4.2%, p = 0.076) while no difference was found after 2 years (13.4% as compared to 11.7%, p greater than 0.2). In a subgroup of patients with anterior MI, precordial mapping with 24 chest leads was analyzed 4 days after arrival in hospital (n = 197). Patients were divided into quartiles according to the sum of R waves, the sum of Q waves, and the number of Q waves. There was a similar overall mortality in each quartile after 1 year and after 2 years regardless of ECG parameters studied. Neither did we find any correlation between the sum of R waves in leads II, III, and aVF on the fourth day in patients with inferior MI and overall 1- or 2-year mortality rate, although there was a trend towards higher mortality with more ECG changes.

Relationship between electrocardiographically and enzymatically estimated size in anterior myocardial infarction

In 179 patients with anterior myocardial infarction the electrocardiographically estimated infarct size was related to serum enzyme activity. A precordial map containing 24 precordial positions and the peak activity of heat stable dehydrogenase (LD; EC 1.1.1.27) were used. A positive correlation was found between the area at risk (initial sum of ST-elevation) and the peak LD activity (r = 0.48 - 0.55; p less than 0.001). When the final Q-and R-wave amplitude were related to peak enzyme activity a better correlation was observed (r = 0.56 - 0.68; p less than 0.001). The sum of R-waves (sigma R) and the sum of Q-waves (sigma Q) in the 24 precordial leads were related to sigma R and sigma Q in five precordial standard leads. A good correlation was found between the two ECG methods (r = 0.75 - 0.83; p less than 0.001), indicating that an increased number of precordial leads gives information regarding the extent of infarction similar to that obtained with the routinely used standard leads. It is concluded that in the individual patient, serum enzyme activity and the final Q-and R-wave changes can give different information about infarct size. If, however, these two independent methods are used in a large number of patients in intervention studies they will probably give similar information about relative influence of the intervention on the mean infarct size.

Long QT: good, bad or indifferent?

A survey of current literature suggests an increasing interest in both the desirable and undesirable implications of a prolonged QT interval, the former perceived to be the beneficial effect of antiarrhythmic drugs that prolong the duration of ventricular action potential, and the latter considered to be a potential marker for sudden cardiac death in patients with ischemic heart disease. In addition, there has been an increasing interest in the congenital long QT syndrome associated with an apparent dysfunction of the autonomic nervous system and serious, potentially lethal ventricular arrhythmias. Circumstantial evidence suggests that these arrhythmias are due to increased dispersion of repolarization which may be aggravated by psychologic and emotional perturbations. In this review, the associations between the long QT interval, autonomic nervous system, dispersion of repolarization, antiarrhythmic drugs and ventricular arrhythmias are examined. Attention is directed to the difficulties of accurate QT measurement, problems related to the correction of the QT interval for heart rate and sex (QTc), the wide range of normal values and the modest QT alterations after various manipulations of the autonomic nervous system. Clinical conditions associated with marked, moderate and occasional QT lengthening are listed and discussed briefly in relation to the disturbances of nervous system, dispersion of ventricular repolarization and ventricular arrhythmias. It is proposed that the absence of relevant animal models of neurogenic or psychogenic QT prolongation hinders the investigation of the neurogenic factors associated with QT lengthening. QT prolongation is most often induced by antiarrhythmic drugs and ischemic heart disease. However, it is not known whether the occurrence of torsade de pointes type of ventricular tachycardia in patients treated with antiarrhythmic drugs is related to a critical drug dose or a critical degree of QTc prolongation. There is no conclusive evidence that QT lengthening has any predictive value either during the acute phase or during convalescence after myocardial infarction. Also, a serious deficiency in current knowledge is the lack of an established relation between the prolonged QT interval and the dispersion of ventricular repolarization. It is concluded that the number of unanswered questions discussed in this review still makes it difficult to judge when a prolonged QT interval is good, bad or indifferent.

Prognostic importance of cholesterol levels after myocardial infarction

The aim of this study was to analyze the relationship between serum cholesterol level and all causes mortality in men who sustained a first myocardial infarction. The cholesterol distribution 3 months after the infarction was established. Ten annual cohorts (n = 1,204) were followed for a maximum period of 11 years. Secondary risk factors were comparable among the groups of the serum cholesterol distribution quintiles according to a multiple logistic prognostic function based on left heart failure, atrial fibrillation, breathlessness on infarction, maximum S-ASAT, relative heart size, and a history of hypertension. When all ages were analyzed together, the total mortality was higher in the upper cholesterol quintiles (P = 0.02). This association was confirmed when analyzed with Coxian adjustments for age, change in smoking habits after infarction, and the previously mentioned prognostic function. When broken down by age (less than or equal to 49, 50-59, greater than or equal to 60) and period of follow-up (3-24 and 25-84 months), the association between mortality and cholesterol quintiles was confined to patients under 50 years during the late follow-up period (P = 0.01), whereas there was no association for the other age groups.