Hospital mortality in acute myocardial infarction in the era of reperfusion therapy (the Myocardial Infarction Triage and Intervention Project)

Effects of intravenous administration of tissue plasminogen activator before thrombectomy in patients with acute myocardial infarction

BACKGROUND

Myocardial salvage after acute myocardial infarction (AMI) largely depends on the removal of infarct-related thrombus. Although both thrombolysis and thrombectomy are effective strategies to remove thrombus, there is a paucity of reports regarding the benefit of the combination therapy. Therefore, the efficacy of intravenous administration with mutant tissue plasminogen activator (Mt-PA) before thrombectomy and ordinary percutaneous coronary intervention (PCI) was evaluated.

METHODS AND RESULTS

Consecutive 44 AMI patients without contraindication of Mt-PA were enrolled in the study and randomly assigned to thrombectomy with Mt-PA pre-administration (group T) or thrombectomy alone (group N). Although Thrombolysis in Myocardial Infarction (TIMI) grade before PCI and TIMI myocardial perfusion grade immediately after PCI were significantly greater in group T (p<0.05), there was no improvement of left ventricular ejection fraction immediately and 6 months after PCI.

CONCLUSIONS

These results suggest that intravenous administration with Mt-PA before thrombectomy had no significant benefit in the salvage of infracted myocardium over thrombectomy alone, despite improvement of coronary microcirculation immediately after PCI.

Applicability of clinical prediction models in acute myocardial infarction: a comparison of traditional and empirical Bayes adjustment methods

INTRODUCTION

Several clinical prediction models have been developed to predict outcome after acute myocardial infarction. Updating to local circumstances may be required to make such models better applicable. We aimed to compare traditional and empirical Bayes (EB) methods to perform such updating.

METHODS

We focused on 16 geographical regions within the GUSTO-I trial, which included 40,830 patients with acute myocardial infarction; of whom, 2851 (7.0%) had died by 30 days. Differences in mortality between regions were studied with traditional adjustment for case mix in logistic regression models and with EB methods. These methods updated predictions for new patients while accounting for the uncertainty in the traditionally estimated mortality differences.

RESULTS

The case mix in the regions differed with respect to important predictive characteristics such as age, presence of shock, and anterior infarct location (all P < .001). These differences did not explain regional differences in 30-day mortality, which varied between 80% and 120% with traditional analyses (P < .01). The EB estimates for regional differences were much smaller (between 93% and 107%).

CONCLUSIONS

Statistically significant differences in case mix and 30-day mortality were noted between geographical regions. The practical implications of this heterogeneity were, however, limited when model predictions were updated with EB methods.

Management and in-hospital outcome of patients with acute myocardial infarction admitted to intensive care units at the turn of the century: results from the French nationwide USIC 2000 registry

OBJECTIVE

To assess actual practices and in-hospital outcome of patients with acute myocardial infarction on a nationwide scale.

METHODS

Of 443 intensive care units in France, 369 (83%) prospectively collected data on all cases of infarction (within < 48 hours of symptom onset) in November 2000.

RESULTS

2320 patients (median age 68 years, 73% men) were included, of whom 83% had ST segment elevation infarction (STEMI). Patients without STEMI were older and had a more frequent history of cardiovascular disease. Median time to admission was 5.0 hours for patients with and 6.5 hours for those without STEMI. Reperfusion therapy was used for 53% of patients with STEMI (thrombolysis 28%, primary angioplasty 25%). In-hospital mortality was 8.7% (5.5% of patients without and 9.3% of those with STEMI). Multivariate analysis found that age, Killip class, lower blood pressure, higher heart rate on admission, anterior location of infarct, STEMI, diabetes mellitus, previous stroke, and no current smoking independently predicted in-hospital mortality. At hospital discharge, 95% received antiplatelet agents, 75% received beta blockers, and over 60% received statins. Angiotensin converting enzyme inhibitors were prescribed for 40% of the patients without and 52% of those with ST elevation.

CONCLUSIONS

This nationwide registry, including all types of centres irrespective of their size and experience, shows continued improvement in patient care and outcomes. Time from symptom onset to admission, however, has not improved in recent years and reperfusion therapy is used for just over 50% of patients with STEMI, with an increasing use of primary angioplasty.

Paradoxical Effect of Smoking in the Spanish Population With Acute Myocardial Infarction or Unstable Angina

OBJECTIVES

The paradoxical effect of smoking after acute myocardial infarction (AMI) is a phenomenon consisting of a reduction in the mortality of smokers compared to nonsmokers. However, it is not known whether the benefit of this reduction in mortality is due to smoking itself or to other covariables. Despite acceptance of the paradoxical effect of smoking in AMI, it is not known whether a similar phenomenon occurs in unstable angina. The objective of this study was to investigate the paradoxical effect of smoking in AMI and unstable angina, and to study specifically whether smoking is an independent prognostic variable.

METHODS AND RESULTS

The study population was selected from the multicentric ARIAM (Análisis del Retraso en el Infarto Agudo de Miocardio [analysis of delay in AMI]) Register, a register of 29,532 patients with a diagnosis of unstable angina or AMI. Tobacco smokers were younger, presented fewer cardiovascular risk factors such as diabetes or hypertension, fewer previous infarcts, a lower Killip and Kimball class, and a lower crude and adjusted mortality in AMI (odds ratio, 0.774; 95% confidence interval, 0.660 to 0.909; p = 0.002). Smokers with unstable angina were younger, with less hypertension or diabetes. In the multivariate analysis, no statistically significant difference in mortality was found.

CONCLUSIONS

The reduced mortality observed in smokers with AMI during their stay in the ICU cannot be explained solely by clinical covariables such as age, sex, other cardiovascular factors, Killip and Kimball class, or treatment received. Therefore, smoking may have a direct beneficial effect on reduced mortality in the AMI population. The lower mortality rates found in smokers with unstable angina are not supported by the multivariate analysis. In this case, the difference in mortality can be explained by the other covariables.

Ambulance Use in Patients With Acute Myocardial Infarction

OBJECTIVE

To explore the choice of transportation mode to hospital in patients experiencing acute myocardial infarction.

METHOD

A descriptive survey study at the Coronary Care Unit of one Swedish University Hospital. The study was carried out between July 2000 and March 2001.

RESULTS

The study population consisted of 114 consecutive patients with acute myocardial infarction. Thirty-two percent stated that they did not know the importance of a short delay when experiencing an acute myocardial infarction. Only 60% called the emergency service number, 112. Patients calling for an ambulance differed from those who did not in several aspects. Medical characteristics associated with ambulance use in a univariate analysis were ST-elevation myocardial infarction and prior history of myocardial infarction. There were no differences regarding gender or age. When looking at the patients' symptom-experience, patients with vertigo or nausea and severe pain chose an ambulance for transport to the hospital. The only significant reasons for not choosing an ambulance were cramping pain and the patient perceiving the symptoms not to be serious. In a multivariate analysis, ST-elevation (OR = 0.30, P = .04), unbearable symptoms (OR = 0.20, P = .03), and nausea (OR = .33, P = .04) appeared as independent predictors of ambulance use and cramping pain (OR = 5.17, P = .01) for not using an ambulance.

CONCLUSIONS

Patients with acute myocardial infarction view the ambulance as an option for transportation to hospital only if they feel really sick. For that reason, it needs to be made well known to the public that ambulances are not only a mode of transport, but also provide diagnostics and treatment.

Mortalidad del infarto de miocardio en el registro PRIMVAC. Factores pronósticos

BACKGROUND AND OBJECTIVE

The aim of this study was to determine the mortality due to acute myocardial infarction in the coronary units from Comunidad Valenciana (Spain) and the prognostic factors associated with a higher mortality.

PATIENTS AND METHOD

Demographic characteristics, coronary risk factors, electrocardiographic ischemic signs, complications and mortality of patients with acute myocardial infarction admitted in the coronary units were collected. The study period comprised January 1995-December 1999. Death incidence was measured during coronary unit's stay. Factors associated with poor prognosis were analyzed.

RESULTS

10.213 patients entered into the study. Mean age at admission was 65 12 years. 23.8% were females (76.2% males). Global mortality in coronary units was 13.3%. Independent variables associated with higher mortality were (p < 0.05): advanced age (OR=1.06 [1.05-1.06]), female sex (OR=1.45 [1.26-1.66]), diabetes mellitus (OR=1.53 [1.35-1.74]), previous myocardial infarction (OR=1.46 [1.23-1.70]), previous angor pectoris (OR=1.29 [1.13-1.49]) and Q-wave infarction (OR=1.23 [1.03-1.43]). Factors associated with lower mortality were: hypercholesterolemia (OR=0.76 [0.66-0.78]), smoking (OR=0.65 [0.57-0.74]) and thrombolysis (OR=0.85 [0.78-0.92]).

CONCLUSIONS

At present, in the reperfusion therapy era, acute myocardial infarction has a high mortality after coronary unit admission. Several clinical factors are associated with a worse prognosis.

Reduction of myocardial ischemic injury following coronary intervention (the MC-1 to Eliminate Necrosis and Damage trial)

Myocardial ischemic injury complicating acute myocardial infarction (AMI) and coronary revascularization procedures remains an unresolved clinical dilemma. In preclinical studies, treatment with pyridoxal-5'-phosphate monohydrate (MC-1), a vitamin B6 metabolite, has demonstrated cardioprotective effects. Sixty patients scheduled for elective percutaneous coronary intervention (PCI) who had clinically high-risk characteristics for ischemic complications were randomized to treatment with MC-1 or placebo in a 2:1 double-blinded fashion. The primary end point was defined as infarct size as measured by area under the curve creatine kinase MB (CK-MB) enzymes. Secondary end points included periprocedural ischemia as assessed by continuous electrocardiographic monitoring, 30-day major adverse cardiac events, and net clinical safety, which included liver function testing. The primary end point, median periprocedural CK-MB area under the curve, was reduced from 32.9 ng/ml in the placebo group to 18.6 ng/ml with MC-1 treatment (p = 0.038), reflecting a shift in the distribution of CK-MB. By categorical classification, the occurrence of 30-day nonfatal AMI did not differ between groups. There were no deaths, and 30-day composite adverse event rates were similar (17.9% MC-1 vs 15.0% placebo, p = 1.0). There were no significant differences in ischemia parameters per continuous electrocardiographic monitoring, and no safety issues were identified. In this phase II pilot study, treatment of high-risk patients who underwent PCI with MC-1 was associated with a decrease in the total amount of CK-MB released after PCI. These results support the evaluation of MC-1 in pivotal trials of patients at risk for developing myocardial ischemia, infarction, or reperfusion injury.

Trends in hospital treatment of ventricular arrhythmias among Medicare beneficiaries, 1985 to 1995

BACKGROUND

Treatment options for patients with ventricular arrhythmias have undergone major changes in the last 2 decades. Trends in use of invasive procedures, clinical outcomes, and expenditures have not been well documented.

METHODS

We used administrative databases of Medicare beneficiaries from 1985 to 1995 to identify patients hospitalized with ventricular arrhythmias. We created a longitudinal patient profile by linking the index admission with all earlier and subsequent admissions and with death records.

RESULTS

Approximately 85,000 patients aged > or =65 years went to hospitals in the United States with ventricular arrhythmias each year, and about 20,000 lived to admission. From 1987 to 1995, the use of electrophysiology studies and implantable cardioverter defibrillators in patients who were hospitalized grew substantially, from 3% to 22% and from 1% to 13%, respectively. Hospital expenditures rose 8% per year, primarily because of the increased use of invasive procedures. Survival improved, particularly in the medium term, with 1-year survival rates increasing between 1987 and 1994 from 52.9% to 58.3%, or half a percentage point each year.

CONCLUSION

Survival of patients who sustain a ventricular arrhythmia is poor, but improving. For patients who are admitted, more intensive treatment has been accompanied by increased hospital expenditures.

Use of emergency medical services for suspected acute cardiac ischemia among demographic and clinical patient subgroups: the REACT trial. Rapid Early Action for Coronary Treatment

OBJECTIVE

Barriers to the use of emergency medical services (EMS) and patient delay in seeking care can limit the receipt or effectiveness of reperfusion therapies and the availability of prehospital emergency cardiac care. The Rapid Early Action for Coronary Treatment (REACT) trial was designed to determine the impact of a community intervention on use of EMS among demographic and clinical subgroups of patients with suspected acute cardiac ischemia.

METHODS

A randomized controlled community trial was conducted in 20 pair-matched communities in the United States. One community from each pair received an 18-month, multicomponent community education program. Data were collected at 44 participating hospitals during a four-month baseline period and throughout the 18-month trial, using medical record abstracts to collect information on mode of transport to the hospital and other sociodemographic and clinical variables. Eligible patients were persons aged > or = 30 years presenting with chest pain or discomfort to emergency departments (EDs) who were admitted and discharged with a cardiac-related diagnoses (ICD 410-414, 427-429, 440, 786.9).

RESULTS

The net change in the odds of EMS use was an increase of 34% in intervention compared with control communities [adjusted odds ratio (OR) 1.34, 95% CI 1.07-1.67]. We observed greater increases in the odds of EMS use among patients who had chronic or other cardiac diagnoses (adjusted OR 1.53, 95% CI 1.18-1.99, and adjusted OR 1.52, 95% CI 1.17-1.97, respectively) than in those diagnosed as having acute ischemia (adjusted OR 1.14, 95% CI 0.91-1.44). We observed greater increases in odds of EMS ulse in those who were retired (adjusted OR 1.62, 95% CI 1.29-2.04) or had systolic blood pressure (SBP) at or below 160 mm Hg upon presentation to the ED (adjusted OR 1.55, 95% CI 1.26-1.91 for SBP 100-160 mm Hg; 1.61, 95% CI 0.88-2.97 for SBP <100 mm Hg).

CONCLUSIONS

The REACT trial demonstrated a significant impact on the use of EMS among patients admitted to the hospital for suspected acute myocardial infarction, with greater increases among patients with chronic or other cardiac ICD-9 discharge diagnoses, those presenting with lower SBP, and retired persons.

Consequences of overutilization and underutilization of thrombolytic therapy in clinical practice. TRACE Study Group. TRAndolapril Cardiac Evaluation

OBJECTIVES

The aim of this study was to evaluate the consequences, measured as mortality and in-hospital stroke, of the use of thrombolytic therapy among patients with acute myocardial infarction (AMI), who do not fulfill accepted criteria or who have contraindications to thrombolytic therapy (i.e., overutilization) and among patients who are withheld thrombolytic treatment despite fulfilling indications and having no contraindications (i.e., underutilization).

BACKGROUND

The implementation of treatment with thrombolysis in clinical practice is not in accordance with the accepted criteria from randomized studies. The consequence has been over- and underutilization of thrombolytic therapy among patients with AMI in clinical practice. The outcome of overutilization of thrombolytic therapy has not been described previously.

METHODS

We examined 6,676 consecutive patients admitted to the hospital with an AMI and recorded characteristics, in-hospital complications and long-term mortality.

RESULTS

Overall, 41% of the patients received thrombolytic therapy. Thrombolytic therapy was underutilized in 14.3% and overutilized in 12.9% of the patients. The use of thrombolytic therapy was associated with reduced mortality in every subgroup examined, including patients without an accepted indication, with an accepted indication and in patients with prior stroke. The risk ratio of in-hospital stroke was not increased in connection with thrombolytic therapy, not even in patients with prior stroke (relative risk = 0.237, 95% confidence interval: 0.031 to 1.810, p = 0.17).

CONCLUSIONS

With the large benefit known to be associated with thrombolytic therapy and the favorable result of thrombolytic therapy in patients with contraindications observed in this study, we conclude that a formal evaluation of thrombolytic therapy in wider patient categories is warranted.

Prognosis of patients with a recurrent acute myocardial infarction before and in the reperfusion era--a national study

BACKGROUND

Patients with recurrent acute myocardial infarction (AMI) are at increased risk for morbidity and mortality. We compared the outcome of patients with recurrent AMI hospitalized in coronary care units in the prereperfusion and reperfusion eras.

METHODS

The study population comprised 2 large-scale cohorts with recurrent AMI: (1) 1415 (24%) of 5839 consecutive patients with AMI hospitalized in 1981 to 1983 (Secondary Prevention Reinfarction Israeli Nifedipine Trial [SPRINT] Registry) and (2) 1093 (25%) of 4317 patients with AMI from three national surveys performed in 1992 to 1996.

RESULTS

Patients in the 1990s had significantly lower rates of heart failure and cardiogenic shock. The 7-day mortality declined from 18% in 1981-1983 to 10% in 1992-1996 (adjusted odds ratio [OR] 0.57 [0.44-0.75]), the 30-day mortality rate from 26% to 16% (OR 0.56 [0.44-0.71]), and the 1-year mortality rate from 39% to 26% (adjusted hazard ratio [HR] 0.64 [0.54-0.75]), respectively. In the 1992-1996 cohort, the adjusted risk of 7-day, 30-day, and 1-year mortality for patients with recurrent AMI treated with thrombolysis in comparison to patients without thrombolysis was OR 1.69 (1.07-2.65), 1.52 (1.03-2.23), and HR 1.18 (0.90-1.55), respectively. The mortality rate among patients treated with early percutaneous transluminal coronary angioplasty/coronary artery bypass grafting was 3% versus 12% at 7 days (OR 0.36 [0.16-0.73]), 7% versus 18% at 30 days (OR 0.45 [0.25-0.77]), and 16% versus 29% at 1 year (HR 0.64 [0.46-0.96]), in comparison to patients without revascularization.

CONCLUSION

The prognosis of patients with recurrent AMI improved significantly during the reperfusion era. Although thrombolysis may have a limited therapeutic effect among patients with recurrent AMI, an interventional approach seems more appropriate when indicated. A randomized trial of thrombolysis versus early revascularization is needed in patients with recurrent AMI.

Prognostic modeling with logistic regression analysis: in search of a sensible strategy in small data sets

Clinical decision making often requires estimates of the likelihood of a dichotomous outcome in individual patients. When empirical data are available, these estimates may well be obtained from a logistic regression model. Several strategies may be followed in the development of such a model. In this study, the authors compare alternative strategies in 23 small subsamples from a large data set of patients with an acute myocardial infarction, where they developed predictive models for 30-day mortality. Evaluations were performed in an independent part of the data set. Specifically, the authors studied the effect of coding of covariables and stepwise selection on discriminative ability of the resulting model, and the effect of statistical "shrinkage" techniques on calibration. As expected, dichotomization of continuous covariables implied a loss of information. Remarkably, stepwise selection resulted in less discriminating models compared to full models including all available covariables, even when more than half of these were randomly associated with the outcome. Using qualitative information on the sign of the effect of predictors slightly improved the predictive ability. Calibration improved when shrinkage was applied on the standard maximum likelihood estimates of the regression coefficients. In conclusion, a sensible strategy in small data sets is to apply shrinkage methods in full models that include well-coded predictors that are selected based on external information.

TIMI risk score for ST-elevation myocardial infarction: A convenient, bedside, clinical score for risk assessment at presentation: An intravenous nPA for treatment of infarcting myocardium early II trial substudy

BACKGROUND

Considerable variability in mortality risk exists among patients with ST-elevation myocardial infarction (STEMI). Complex multivariable models identify independent predictors and quantify their relative contribution to mortality risk but are too cumbersome to be readily applied in clinical practice.

METHODS AND RESULTS

We developed and evaluated a convenient bedside clinical risk score for predicting 30-day mortality at presentation of fibrinolytic-eligible patients with STEMI. The Thrombolysis in Myocardial Infarction (TIMI) risk score for STEMI was created as the simple arithmetic sum of independent predictors of mortality weighted according to the adjusted odds ratios from logistic regression analysis in the Intravenous nPA for Treatment of Infarcting Myocardium Early II trial (n=14 114). Mean 30-day mortality was 6.7%. Ten baseline variables, accounting for 97% of the predictive capacity of the multivariate model, constituted the TIMI risk score. The risk score showed a >40-fold graded increase in mortality, with scores ranging from 0 to >8 (P:<0.0001); mortality was <1% among patients with a score of 0. The prognostic discriminatory capacity of the TIMI risk score was comparable to the full multivariable model (c statistic 0. 779 versus 0.784). The prognostic performance of the risk score was stable over multiple time points (1 to 365 days). External validation in the TIMI 9 trial showed similar prognostic capacity (c statistic 0.746).

CONCLUSIONS

The TIMI risk score for STEMI captures the majority of prognostic information offered by a full logistic regression model but is more readily used at the bedside. This risk assessment tool is likely to be clinically useful in the triage and management of fibrinolytic-eligible patients with STEMI.

Impact of community intervention to reduce patient delay time on use of reperfusion therapy for acute myocardial infarction: rapid early action for coronary treatment (REACT) trial. REACT Study Group

BACKGROUND

Reperfusion therapy for acute myocardial infarction (AMI) is a time-dependent intervention that can reduce infarct-related morbidity and mortality. Out-of-hospital patient delay from symptom onset until emergency department (ED) presentation may reduce the expected benefit of reperfusion therapy.

OBJECTIVE

To determine the impact of a community educational intervention to reduce patient delay time on the use of reperfusion therapy for AMI.

METHODS

This was a randomized, controlled community-based trial to enhance patient recognition of AMI symptoms and encourage early ED presentation with resultant increased reperfusion therapy rates for AMI. The study took place in 44 hospitals in 20 pair-matched communities in five U.S. geographic regions. Eligible study subjects were non-institutionalized patients without chest injury (aged > or =30 years) who were admitted to participating hospitals and who received a hospital discharge diagnosis of AMI (ICD 410); n = 4,885. For outcome assessment, patients were excluded if they were without survival data (n = 402), enrolled in thrombolytic trials (n = 61), receiving reperfusion therapy >12 hours after ED arrival (n = 628), or missing symptom onset or reperfusion times (n = 781). The applied intervention was an educational program targeting community organizations and the general public, high-risk patients, and health professionals in target communities. The primary outcome was a change in the proportion of AMI patients receiving early reperfusion therapy (i.e., within one hour of ED arrival or within six hours of symptom onset). Trends in reperfusion therapy rates were determined after adjustment for patient demographics, presenting blood pressure, cardiac history, and insurance status. Four-month baseline was compared with the 18-month intervention period.

RESULTS

Of 3,013 selected AMI patients, 40% received reperfusion therapy. Eighteen percent received therapy within one hour of ED arrival (46% of treated patients), and 32% within six hours of symptom onset (80% of treated patients). No significant difference in the trends in reperfusion therapy rates was attributable to the intervention, although increases in early reperfusion therapy rates were noted during the first six months of the intervention. A significant association of early reperfusion therapy use with ambulance use was identified.

CONCLUSIONS

Community-wide educational efforts to enhance patient response to AMI symptoms may not translate into sustained changes in reperfusion practices. However, an increased odds for early reperfusion therapy use during the initiation of the intervention and the association of early therapy with ambulance use suggest that reperfusion therapy rates can be enhanced.

Clinical trials in acute myocardial infarction: should we adjust for baseline characteristics?

BACKGROUND

Clinical trials concerning acute myocardial infarction often evaluate short-term death. Several baseline characteristics are predictors of death, most notably age. Adjustment for one or more predictors in a multivariable analysis may be considered to correct the estimate of the treatment effect for any imbalance that by chance may have occurred between the randomized groups. Moreover, adjustment results in a stratified estimate of the effect of treatment.

METHODS AND RESULTS

The effects of adjustment (correction for imbalance and stratification) were studied with logistic regression analysis in the Global Use of Strategies to Open Occluded Coronary Arteries (GUSTO)-I trial. The primary end point was 30-day death, which occurred in 6.3% of 10,348 patients randomly assigned to tissue plasminogen activator and 7.3% of 20,162 patients randomly assigned to streptokinase thrombolytic therapy. This is equivalent to an unadjusted odds ratio of 0.853. No significant imbalance had occurred for any of 17 baseline characteristics considered, including well-known demographic, presenting, and history characteristics. Adjusted for age, the odds ratio was 0.829, which is an 18% increase in estimated effect on the logistic scale. When adjusted for 17 characteristics, the odds ratio was 0.820, an increase of 25%. The increase in effect estimate was largely explained by the stratification effect and only partly by imbalance of predictors.

CONCLUSIONS

Adjustment for predictive baseline characteristics, even when largely balanced, may lead to clearly different estimates of the treatment effect on mortality rates. Adjustment for important predictors such as age is recommended in clinical trials studying patients with acute myocardial infarction.

Prognostic modelling with logistic regression analysis: a comparison of selection and estimation methods in small data sets

Logistic regression analysis may well be used to develop a prognostic model for a dichotomous outcome. Especially when limited data are available, it is difficult to determine an appropriate selection of covariables for inclusion in such models. Also, predictions may be improved by applying some sort of shrinkage in the estimation of regression coefficients. In this study we compare the performance of several selection and shrinkage methods in small data sets of patients with acute myocardial infarction, where we aim to predict 30-day mortality. Selection methods included backward stepwise selection with significance levels alpha of 0.01, 0.05, 0. 157 (the AIC criterion) or 0.50, and the use of qualitative external information on the sign of regression coefficients in the model. Estimation methods included standard maximum likelihood, the use of a linear shrinkage factor, penalized maximum likelihood, the Lasso, or quantitative external information on univariable regression coefficients. We found that stepwise selection with a low alpha (for example, 0.05) led to a relatively poor model performance, when evaluated on independent data. Substantially better performance was obtained with full models with a limited number of important predictors, where regression coefficients were reduced with any of the shrinkage methods. Incorporation of external information for selection and estimation improved the stability and quality of the prognostic models. We therefore recommend shrinkage methods in full models including prespecified predictors and incorporation of external information, when prognostic models are constructed in small data sets.

Optimising care of acute myocardial infarction: results of a regional quality improvement project

The effects of a quality improvement intervention were evaluated in a before-after time-series study of 649 consecutive patients suffering acute myocardial infarction (AMI) in the West Moreton Health District over 2.5 years from March 1996 through to August 1998. After a 6-month baseline period, clinical practice guidelines were issued followed by sequential feedback to providers of clinical indicator data over a 1-year period. Resultant changes in practice were then evaluated during a 12-month post-intervention period. The proportion of eligible patients receiving early thrombolysis, lipid-lowering drugs and cardiac rehabilitation increased, respectively, from 30.8 to 70.0% (P = 0.001), from 23.4 to 56.4% (P = 0.003), and from 23.6 to 54.3% (P = 0.003). The in-hospital death rate, incidence of postinfarct angina and mean length of stay decreased, respectively, from 15.8 to 8.6% (P = 0.02), from 30.1 to 14.3% (P < 0.001), and from 7.4 to 6.3 days (P = 0.001). Despite the absence of control groups, the present study suggested that clinical guidelines combined with feedback of clinical indicators were useful in improving quality of care.

Clinical predictors of heart failure in patients with first acute myocardial infarction

BACKGROUND

The occurrence of heart failure associated with an acute myocardial infarction has a strong adverse effect on long-term morbidity and mortality. The prediction and prevention of heart failure could influence these adverse events.

METHODS AND RESULTS

We studied 483 consecutive patients who had their first acute myocardial infarction and who were admitted within 24 hours of the onset of symptoms. Heart failure was defined as the presence of pulmonary rales or an S3 gallop, or the presence of alveolar or interstitial edema by radiograph. Baseline demographic data, determination of peak creatine phosphokinase level, echocardiographic left ventricular ejection fraction, blood pressure, and pulse were obtained. Heart failure occurred in 41.6% (201 of 483) of the patients. We observed a bimodal occurrence of heart failure with an early occurrence at admission in 4% (20 of 483) followed by a second increase beginning after the fourth day of admission in 39% of the remaining patients (181 of 463). Predictors of early heart failure were older age, diabetes mellitus, or previous cardiac symptoms, whereas the predictors of heart failure after the fourth day included the same demographic predictors in addition to a history of hypertension, male sex, increased peak creatine phosphokinase level and heart rate, and decrease in left ventricular ejection fraction. In-hospital death occurred in 5.3% compared with 1.4% (P =.012) in patients who did and did not have heart failure, respectively. The occurrence of heart failure during hospital admission also adversely affected the 18-month follow-up, with 14.9% deaths in the patients with heart failure and 6.4% in those without heart failure (P =.002).

CONCLUSION

Heart failure is frequently associated with acute myocardial infarction and occurs with a bimodal distribution and is associated with increased risk of death during hospitalization and during 18 months of follow-up. Predictors of early heart failure include previous medical conditions and age. The second peak occurrence can be predicted by similar characteristics in addition to increased peak creatine phosphokinase level, decreased left ventricular ejection fraction, and increased heart rate.

[Changes in hospital mortality from acute myocardial infarction during the last 15 years. The impact of reperfusion treatments]

INTRODUCTION AND OBJECTIVES

There are not any conclusive data about the changes in in-hospital mortality in a non-selected series of patients admitted with acute myocardial infarction in different periods of time. We studied the in-hospital mortality of three extensive series of patients admitted to our Coronary Care Unit during different periods of time, the influence of reperfusion methods and their early application, as well as the changes in baseline characteristics of the three populations studied.

METHODS

The in-hospital mortality of 1,858 consecutively-admitted patients during three different periods of time (1983-1986, 1992-1994, and 1995-1998) were studied. The demographic data, the previous history and risk factors, the evolution during the acute phase and the treatment prescribed with special attention to the reperfusion methods applied and the delay on its administration were compared.

RESULTS

The differences in the baseline characteristics of the populations studied are described. In the two groups of the nineteen-nineties, an increase in the age and in the percentage of women, diabetics and hypertensives was compared. As for the characteristics of acute myocardial infarction, an increase of patients in Killip class 3 and 4 stands out besides other changes. Fibrinolitic treatment decreased during the third period due to the increment in primary angioplasty. There were no significant differences in hospital mortality among the three series studied. The treatment with thrombolysis and primary angioplasty during the first two hours showed a significant independent reduction of mortality.

CONCLUSIONS

The early application of thrombolysis and primary angioplasty showed an independent reduction of the hospital mortality in our study. Nevertheless the non-adjusted mortality rate did not show any change during the last 15 years.

Long-term (three-year) prognosis of patients treated with reperfusion or conservatively after acute myocardial infarction. Israeli Thrombolytic Survey Group

OBJECTIVES

This survey sought to assess the frequency of the use of thrombolytic therapy, invasive coronary procedures (ICP) (angiography, percutaneous transluminal coronary angioplasty and coronary artery bypass grafting [CABG]), variables associated with their use, and their impact on early (30-day) and long-term (3-year) mortality after acute myocardial infarction (AMI).

BACKGROUND

Few data are available regarding the implementation in daily practice of the results of clinical trials of treatments for AMI and their impact on early and long-term prognosis in unselected patients after AMI.

METHODS

A prospective community-based national survey was conducted during January-February 1994 in all 25 coronary care units operating in Israel.

RESULTS

Among 999 consecutive patients with an AMI (72% men; mean age 63+/-12 years) acute reperfusion therapy (ART) was used in 455 patients (46%; thrombolysis in 435 patients [44%] and primary angioplasty in 20 [2%]). Its use was independently associated with anterior AMI location and hospitals with on-site angioplasty facilities, whereas advancing age, prior myocardial infarction (MI) and prior angioplasty or CABG were independently associated with its lower use. The three-year mortality of patients treated with ART was lower than in counterpart patients (22.0% vs. 31.4%, p = 0.0008), mainly as the result of 30-day to 3-year outcome (12.4% vs. 21.1%; hazard ratio = 0.73, 95% confidence interval [CI] 0.52 to 1.03). Independent predictors of long-term mortality were: age, heart failure on admission or during the hospitalization, ventricular tachycardia or fibrillation and diabetes. The outcome of patients not treated with ART differed according to the reason for the exclusion, where patients with contraindications experienced the highest three-year (50%) mortality rate. After ART, coronary angiography, angioplasty and CABG were performed in-hospital in 28%, 12% and 5% of patients, respectively. Their use was independently associated with recurrent infarction or ischemia, on-site catheterization or CABG facilities, non-Q-wave AMI and anterior infarct location. In the entire study population, and in patients with a non-Q-wave AMI, performance of ICP was associated with lower 30-day mortality (odds ratio [OR] = 0.53, 95% CI 0.25 to 0.98, and OR = 0.21, 0.03 to 0.84, respectively), but not thereafter.

CONCLUSIONS

This survey demonstrates the extent of implementation in daily practice of ART and ICP and their impact on early and long-term prognosis in an unselected population after AMI.

Hospital mortality of acute myocardial infarction in the thrombolytic era

OBJECTIVE

To examine the management and outcome of an unselected consecutive series of patients admitted with acute myocardial infarction to a tertiary referral centre.

DESIGN

A historical cohort study over a three year period (1992-94) of consecutive unselected admissions with acute myocardial infarction identified using the HIPE (hospital inpatient enquiry) database and validated according to MONICA criteria for definite or probable acute myocardial infarction.

SETTING

University teaching hospital and cardiac tertiary referral centre.

RESULTS

1059 patients were included. Mean age was 67 years; 60% were male and 40% female. Rates of coronary care unit (CCU) admission, thrombolysis, and predischarge angiography were 70%, 28%, and 32%, respectively. Overall in-hospital mortality was 18%. Independent predictors of hospital mortality by multivariate analysis were age, left ventricular failure, ventricular arrhythmias, cardiogenic shock, management outside CCU, and reinfarction. Hospital mortality in a small cohort from a non-tertiary referral centre was 14%, a difference largely explained by the lower mean age of these patients (64 years). Five year survival in the cohort was 50%. Only age and left ventricular failure were independent predictors of mortality at follow up.

CONCLUSIONS

In unselected consecutive patients the hospital mortality of acute myocardial infarction remains high (18%). Age and the occurrence of left ventricular failure are major determinants of short and long term mortality after acute myocardial infarction.

[The characteristics, management and prognosis of the acute myocardial infarct patient in the Valencian Community in 1995: the results of the PRIMVAC Registry (The Registry Project of Acute Myocardial Infarct in Valencia, Alicante and Castellón). As representatives of the PRIMVAC investigators]

BACKGROUND AND OBJECTIVES

Regional registers of patients with acute myocardial infarction are scarce in Spain. The PRIMVAC register (Proyecto de Registro de Infarto agudo de Miocardio de Valencia, Alicante y Castellón) was initiated to obtain updated information on the management of these patients in the Valencia Autonomous Community. Data of the first twelve months of the register are presented.

METHODS

The 17 participating hospitals cover 2,833,938 inhabitants. Demographic, clinical, procedural and outcome data as well as predictive variables of mortality were analysed in the patients with acute myocardial infarction during their stay in the coronary care units from 1 December 1994 to 30 November 1995.

RESULTS

During 12 months, 2,377 patients were included. Mean age was 65.3 years (SD 11.9) and 23.2% were female. Left ventricular failure was present in 39.8%. Thrombolytic therapy was applied in 42.1% with a median time delay of 195 min from chest pain onset. This time was longer in the women (250 min) and in the elderly (210 min). The in-coronary-care-unit-mortality rate was 13.9%. Age, female gender, diabetes, previous myocardial infarction, Q wave and right ventricular infarction independently predicted increased early mortality.

CONCLUSION

Present data show the feasibility of an acute myocardial infarction register in the Valencia Autonomous Community. Although an acceptable level of thrombolysis has been reached, the mortality rate is still high. The long delay in initiating thrombolysis, particularly in female and elderly patients is remarkable.

Combined effect of age and right ventricular involvement on acute inferior myocardial infarction prognosis

BACKGROUND

In patients with acute inferior myocardial infarction (AIMI), right ventricular involvement (RVI) is one of the strongest predictors of in-hospital death. We hypothesized that the impact of RVI on AIMI prognosis depends on the patient's age.

METHODS AND RESULTS

The in-hospital clinical outcome of 798 consecutive patients admitted to the coronary care unit within 48 hours of symptom onset with AIMI was analyzed according to patient age and to the presence of RVI diagnosed by ECG and/or echocardiographic criteria. The total incidence of RVI was 37%, and it increased as age advanced. Patients with RVI had a significantly higher incidence of major complications (45% versus 19%, P<0.0001) and a higher in-hospital mortality rate (22% versus 6%, P<0.0001). The prognostic effect of RVI was independent of sex, smoking, diabetes, shock on admission, left ventricular ejection fraction, and reperfusion therapy, all age-dependent predictors. A multivariate analysis showed a significant (P=0.03) interaction between age and RVI on AIMI mortality. RVI increased mortality risk only in the oldest patients.

CONCLUSIONS

In patients with AIMI, RVI substantially increases mortality risk in elderly patients, whereas it has a nonsignificant effect in young subjects.

Early mortality after acute myocardial infarction: observational study in Yamagata, 1993-1995

Although considerable information is available regarding the prognosis after acute myocardial infarction (AMI) in Western populations, little is known about the fate of Japanese subjects after AMI. The purpose of this study was to assess short-term mortality and factors influencing it after AMI in Japan. From April 1993 to December 1995, 1,014 patients with AMI from 41 hospitals in Yamagata Prefecture were registered by cardiologists for the prospective survey. Among patients who died within 28 days after the onset of AMI, immediate causes of death were examined and the clinical profiles of these subjects were compared with those of patients that survived. Early death occurred in 184 patients (short-term mortality 18%). Patients who died were significantly older than survivors (76.1+/-9.4 vs 67.6+/-11.8 years, p<0.01). They were also more likely to be women (50% vs 31%, p<0.01), to have had hypertension (64% vs 54%, p<0.05), diabetes mellitus (29% vs 20%, p<0.02), prior MI (17% vs 12%, p<0.05), or Killip class III or IV disease (63% vs 15%, p<0.01), and were significantly less likely to be current smokers (26% vs 45%, p<0.01) or to have been treated with reperfusion therapy (27% vs 63%, p<0.01). Multivariate logistic analysis demonstrated that independent predictors of early death were Killip class III or IV and advanced age. Reperfusion therapy was a negative predictor of death. Patients who died had arrived at hospital earlier than patients who survived. Mortality as a result of heart failure, cardiac rupture, or arrhythmia fell exponentially after the onset of AMI. Thus, the predictors of short-term mortality were similar to those reported in Western populations. More deaths occurred just after the onset of disease, suggesting that early therapy is important in reducing short-term mortality.

Management of acute myocardial infarction in intensive care units in 1995: a nationwide French survey of practice and early hospital results

OBJECTIVES

This survey sought to determine actual practices in the management of acute myocardial infarction on a nationwide scale.

BACKGROUND

Few data are available regarding the adoption of clinical trial results of treatment of myocardial infarction into "real-world" clinical practice.

METHODS

Of 501 intensive care units in France, 373 (74%) collected data from all patients with myocardial infarction admitted within 48 h of symptom onset during November 1995.

RESULTS

Data from 2,563 patients (71% men; mean age [+/-SD] 67 +/- 14 years) were included. Time from symptom onset to admission was <6 h in 1,467 patients (62%). Thrombolysis was used in 822 patients (32%) and primary angioplasty in 330 (13%). The use of reperfusion therapy decreased markedly with age. During the first 5 days, heparin was prescribed in 96% of patients, aspirin in 89%, nitrates in 87%, beta-adrenergic blocking agents in 64%, angiotensin-converting enzyme inhibitors in 46% and calcium antagonists in 17%. Coronary angiography was performed in 33% of patients, and 58% had echocardiographic assessment of left ventricular ejection fraction (LVEF). Median LVEF was 50%. The 5-day mortality rate was 7.7% compared with 12.1% in a previous French survey carried out in 1984. By multivariate analysis, independent predictors of mortality were age, anterior infarction, history of stroke and heart failure and, when added to the model, Killip class and LVEF.

CONCLUSIONS

This survey shows that the results of therapeutic trials have largely translated to clinical practice, resulting in improved early outcome compared with the early 1980s. However, continuous efforts should be made to shorten the time delay before hospital admission and to increase the proportion of elderly patients receiving reperfusion therapy.

Clinical perspectives on the use of composite endpoints

Although mortality is the most important endpoint in evaluating new regimens, insistence on its use as the only endpoint in clinical trials can require that thousands of patients be studied. Accordingly, composite endpoints have been increasingly used to increase the overall event rate and thereby reduce the number of patients needed for the trial. For use as part of composite endpoint, nonfatal endpoints should be clinically meaningful, i.e., related to an adverse subsequent prognosis. In acute myocardial infarction (MI), several intermediate endpoints in the well-described pathophysiology of acute MI have been correlated with an adverse long-term outcome: recurrent MI, new onset congestive heart failure or cardiogenic shock, left ventricular dysfunction, large infarct size, and failure to achieve early patency of the infarct-related artery. Furthermore, in acute MI, new therapies that improve these nonfatal endpoints also improve mortality, thereby validating this approach. Once this link is established, such nonfatal endpoints can be validly used in evaluating new therapies. Note, however, if this link has not been made (that mortality is reduced when there is a reduction in the nonfatal endpoint), as in the case of suppression of ventricular premature complexes with antiarrhythmic therapy, the nonfatal endpoint cannot be used validly. Thus, appropriately designed and validated composite endpoints can provide a valid means of testing new treatments in a smaller trial than one using mortality alone. Their use should allow testing of a greater number of new regimens, thereby allowing more rapid progress toward improving the clinical outcome of patients.

Time delay in the treatment of acute myocardial infarction (AMI): a comparison of primary percutaneous transluminal coronary angioplasty (PTCA) with thrombolysis

BACKGROUND

If primary percutaneous transluminal coronary angioplasty (PTCA) cannot be performed within times comparable to thrombolysis, the possible advantages of that management may be offset by the logistic difficulties associated with its delivery.

AIM

To measure and compare the time delay involved in administration of thrombolysis and primary PTCA over a one year period and examine causes for delay greater than 60 minutes.

METHOD

Prospective data collection on all patients treated with primary PTCA or thrombolysis. A quality improvement process was applied.

RESULTS

Eighty-five patients were treated with thrombolysis with a delay of 39 +/- 8 (SD) minutes, 12 patients being treated more than 60 minutes after presentation. Primary PTCA was used in 79 patients with a delay of 48 +/- 12 (SD) minutes, 21 patients being treated after more than 60 minutes. Time delays in the two management groups were significantly different (p = 0.03) but that in primary PTCA during routine hours was not significantly different from that in thrombolysis treated patients (p = 0.07). Causes for revascularisation delay greater than 60 minutes from presentation are discussed.

CONCLUSIONS

With appropriate facilities and organisation, patients with acute myocardial infarction presenting within normal working hours can be treated with primary PTCA without compromising their care due to time delay. Many patients managed with primary revascularisation by thrombolysis or primary PTCA with a delay of more than 60 minutes have identifiable clinically appropriate delays.

Prospective validation of a composite end point in thrombolytic trials of acute myocardial infarction (TIMI 4 and 5). Thrombosis In Myocardial Infarction

Although the use of composite end points in clinical trials has increased in recent years, few data are available on the validity of such an approach. In the Thrombolysis In Myocardial Infarction (TIMI) 4 and 5 trials, we set out to validate prospectively the nonfatal components of the "unsatisfactory outcome" end point. This end point consisted of the in-hospital occurrence or observation of new-onset severe congestive heart failure/shock, left ventricular ejection fraction <40% (or <30% for patients with prior myocardial infarction), reinfarction, reocclusion by sestamibi perfusion imaging, TIMI flow grade <2 at 90 minutes or 18 to 36 hours, intracranial hemorrhage, major spontaneous hemorrhage, or anaphylaxis. Among 576 patients in TIMI 4 and 5 with 1-year follow-up, a nonfatal unsatisfactory outcome end point was reached in hospital in 45% of patients. Compared with patients without such an end point, patients with an end point had a relative risk of 1-year mortality of 2.5 (95% confidence interval 1.4 to 5.6, p = 0.001). For individual components, new-onset severe congestive heart failure/shock had a relative risk of 4.6 (p = 0.001), left ventricular ejection fraction <40% had a relative risk of 3.5 (p = 0.006), recurrent myocardial infarction had a relative risk of 2.2 (p = 0.047), and TIMI flow grade <2 at 90 minutes had a relative risk of 2.2 (p = 0.005). Our findings show that these nonfatal in-hospital end points and the composite end point are associated with an increased risk of 1-year mortality and as such are valid predictive survival markers for use in clinical trials.

[Clinical prediction of the early prognosis in acute myocardial infarct]

Several clinical factors can influence the pathophysiology, clinical course and prognosis of acute myocardial by different means. Some of them may be easily detected through the history, physical examination or ECG in an early phase. The knowledge of these factors may help the therapeutic decision making of patients with myocardial infarction. The influence for the main clinical factors (age, sex, risk factors, cardiologic antecedents and evolutive findings) on the short-term prognosis of acute myocardial infarction is reviewed. An analysis of the likely mechanisms of the influence of these factors on infarct prognosis is also performed.

Acute myocardial infarction without thrombolytic therapy: beneficial effects of magnesium sulfate

Only one third of hospitalized patients with acute myocardial infarction (AMI) receive thrombolytic therapy despite its proven benefits on outcomes. Elderly patients, have a greater risk of death during myocardial infarction; however, thrombolytic therapy appears to be less used in these patients, as compared to the general AMI-patients. In order to evaluate the impact of magnesium supplementation in AMI-patients without thrombolytic therapy, 194 patients participated in a prospective, randomized and placebo-controlled study: 96 patients received a 48-hour intravenous magnesium sulfate and 98 isotonic glucose as placebo. Magnesium infusion reduced the incidence of arrhythmias, congestive heart failure and in-hospital-mortality compared with placebo (27 vs. 40%, p = 0.04; 18 vs. 23%, p = 0.27; 4 vs. 17%, p < 0.01, respectively); in the subgroup of elderly patients (> 70 years), the benefit was also obvious (42 vs. 50%; 18 vs. 25%; 9 vs. 23%, p = 0.09, respectively). These data suggest that intravenous magnesium supplementation might be justified in order to reduce myocardial damage and mortality rate in subsets of high-risk patients such the elderly and/or patients not suitable for thrombolysis. Additional trials appear to be indicated to evaluate the potential benefit of magnesium in well defined specific subsets of AMT-patients.

[The RICVAL study. Acute myocardial infarct in the city of Valencia. Data on 1,124 patients during the first twelve months of the registry (December, 1993--November, 1994)]

BACKGROUND AND OBJECTIVES

Information on the management of acute myocardial infarction in Spain is still scarce. The Register of Acute Myocardial Infarction of Valencia City (RICVAL) was established to collect, in a prospectively and uniformly way, data of patients with acute myocardial infarctions discharged from Valencia coronary care units, in order to obtain updated information on the management of these patients. Data of the first twelve months of the register are presented.

METHODS

Using standardised variables, demographic, clinical, procedural and outcome data from patients with acute myocardial infarction were collected at the eight hospitals collaborating in the RICVAL, from 1 December 1993 to 30 November 1994.

RESULTS

The eight participating hospitals cover 1,665,720 people. During 12 months, 1,124 patients were discharged from the participating coronary care units. Mean age was 65.1 years and 23.9% were female. The case fatality rate was 16.9%. Left ventricular failure (Killip 2, 3 and 4) was present in 42%. Thrombolytic therapy was applied in 43.5% with a median time delay of 210 minutes from chest pain onset. The delay time in initiating thrombolysis was longer in the women and in the elderly.

CONCLUSION

Analysis of present data shows the feasibility of an acute myocardial infarction register in Valencia City. The RICVAL study will allow a better knowledge of demographic, clinical, procedural and outcome data in patients with myocardial infarction. The case fatality rate is still high when we consider that an acceptable level of thrombolytic therapy has been reached. The long delay time in initiating thrombolysis, particularly in the elderly and in the women, must be emphasized.

Incidence of cardiac arrest during self-transport for chest pain

STUDY OBJECTIVE

To assess the incidence of cardiac arrest among patients who use self-transport to seek medical care for chest pain.

METHODS

This was a retrospective cohort study of patients admitted to a CCU for suspected acute myocardial infarction (AMI) and patients experiencing out-of-hospital cardiac arrest preceded by symptoms in King County, Washington, between January 1, 1992, and July 31, 1994. Participants were identified through use of the databases compiled by the Myocardial infarction Triage and intervention Trial, which reviewed medical records in all area hospitals, and the Cardiac Arrest Surveillance System, which tracks all incidences in which CPR is performed by EMS personnel in King County. Patients whose sudden cardiac arrests were not preceded by symptoms were excluded. Hospital records were abstracted to find the means of transport for patients admitted to CCUs. For cardiac arrest patients, the medical history, presence of symptoms, means of transport, and prehospital death information were abstracted from paramedic field reports. Outcome (admission, discharge, or in-hospital death) was obtained from hospital records. An event cause (cardiac or other) was determined from death certificates, hospital records, or consultation with private physicians.

RESULTS

During the 30-month study period, 13,187 patients sought help for cardiac symptoms and were either admitted to a CCU or died before admission after calling 911. A majority, 7,393 (59%), were transported by emergency medical services, and 5,182 (41%) used private transportation to obtain medical care; the means of transport could not be determined for 612 patients. Of the EMS group, 6,978 were admitted to the hospital without experiencing prehospital cardiac arrest, and 415 (5.6%) arrested before arriving at the hospital. Of the group using private transportation, 5,164 were admitted without arresting and 18 (.35%) arrested before arrival, after which 911 was called (P < .001).

CONCLUSION

The incidence of cardiac arrest among patients who attempted to reach the hospital by private transportation was very low compared with the incidence among those who chose the EMS system for transport. This suggests that patient self-selection occurs, with the more seriously ill patients more commonly calling 911 for transport.

Smoking and prognosis after acute myocardial infarction in the thrombolytic era (Israeli Thrombolytic National Survey)

OBJECTIVES

This study sought to compare the relation between smoking and the 30-day and 6-month outcome after acute myocardial infarction in an Israeli nationwide survey.

BACKGROUND

Studies before and during the thrombolytic era reported similar or lower early mortality after acute myocardial infarction in smokers than in nonsmokers. This finding is intriguing and may be misleading because numerous epidemiologic studies have clearly shown that smoking is an independent risk factor for atherosclerosis, myocardial infarction and death.

METHODS

The study cohort comprised 999 consecutive patients with an acute myocardial infarction from a prospective nationwide survey conducted during January and February 1994 in all coronary care units operating in Israel. The prognosis of 367 patients (37%) who were smokers (current smokers and those who smoked up to 1 month before admission) was compared with that of 632 nonsmokers (past smokers or those who never smoked).

RESULTS

Smokers were on average 10 years younger and were more frequently men and patients with a family history of coronary heart disease and inferior infarction and less frequently patients with a previous infarction or a history of angina, hypertension and diabetes than nonsmokers. Smokers also had a lower incidence of congestive heart failure on admission or during the hospital period. Thrombolytic therapy (49% vs. 40%, p < 0.01) and aspirin (89% vs. 80%, p < 0.001) were administered more frequently in smokers than nonsmokers. The crude 30-day (6.0% vs. 15.7%) and cumulative 6-month (7.9% vs. 21.5%) mortality rates were significantly lower (p < 0.0001 for both) in smokers than nonsmokers, respectively. However, after adjustment for age, baseline characteristics, thrombolytic therapy and invasive coronary procedures, the lower 30-day (odds ratio [OR] 0.75, 95% confidence interval [CI] 0.43 to 1.29, p = 0.30) and 6-month (hazard ratio 0.84, 95% CI 0.54 to 1.30, p = 0.42) mortality rates in smokers and nonsmokers were not significantly different. The model had a power of 0.80 for OR 0.50, with alpha 0.1.

CONCLUSIONS

In our nationwide survey, the seemingly better prognosis of smokers early after acute myocardial infarction was no longer evident after adjustment for baseline and clinical variables and may be explained by their younger age and a more favorable risk profile. Smokers develop acute myocardial infarction a decade earlier than nonsmokers. Efforts to lower the prevalence of smoking should continue.

Magnesium in acute myocardial infarction: overview of available evidence

Despite improvements in the outcome of patients with acute myocardial infarction (MI) during the past three decades, room for improvement exists in elderly patients and in patients who are not candidates for thrombolysis. Animal models suggest that magnesium supplementation before reperfusion reduces infarct size. Statistical analysis of the randomized trials of magnesium in MI reveals a gradient of response. When higher risk patients were enrolled, a greater benefit of magnesium was observed; progressively smaller benefits of magnesium occurred as the control group mortality approached 7%, at which point no benefit was detected. Although the ISIS-4 study enrolled more than 58,000 patients, no reduction in mortality was seen, probably as a result of a low control group mortality and relatively late administration of the magnesium. Because the potential benefit of magnesium in MI remains an open question, additional trials are needed before this inexpensive and easily administered therapy is prematurely cast aside.

A composite view of cardiac rupture in the United States National Registry of Myocardial Infarction

OBJECTIVES

This study was done to determine the incidence, timing and prevalence as a cause of death from cardiac rupture in patients with acute myocardial infarction.

BACKGROUND

Several clinical trials and overview analyses have suggested that the survival benefit conferred by thrombolytic therapy may be offset by a paradoxic increase in early deaths from cardiac rupture.

METHODS

Demographic, procedural and outcome data from patients with acute myocardial infarction were collected at 1,073 United States hospitals collaborating in the United States National Registry of Myocardial Infarction.

RESULTS

Among the 350,755 patients enrolled, 122,243 received thrombolytic therapy. In-hospital mortality for the overall patient population, those not treated with thrombolytics (n = 228,512) and those given thrombolytics were 10.4%, 12.9% and 5.9%, respectively (p<0.001). Cardiogenic shock was the most common cause of death in each patient group. Although the incidence of cardiac rupture was low (<1.0%), it was responsible for 7.3%, 6.1% and 12.1%, respectively, of in-hospital deaths (p<0.001). Death from rupture occurred earlier in patients given thrombolytic therapy, with a clustering of events within 24 h of drug administration. Despite the early risk, death rates were comparatively low in thrombolytic-treated patients on each of the first 30 days. By multivariable analysis, thrombolytics, prior myocardial infarction, advancing age, female gender and intravenous beta-blocker use were independently associated with cardiac rupture.

CONCLUSIONS

This large registry experience, including over 350,000 patients with myocardial infarction, suggests that thrombolytic therapy accelerates cardiac rupture, typically to within 24 to 48 h of treatment. The possibility that rupture represents an early hemorrhagic complication of thrombolytic therapy should be investigated.

A population-based assessment of the use and effectiveness of thrombolytic therapy. The Corpus Christi Heart Project

Little is known regarding the use and effectiveness of thrombolytic therapy in community settings, especially regarding the receipt of therapy by Mexican Americans. Thus, we examined the factors associated with receipt of thrombolysis and the survival experience of recipients and nonrecipients in the Corpus Christi Heart Project. The Corpus Christi Heart Project is a population-based surveillance program for hospitalized myocardial infarction among Mexican-American and non-Hispanic white women and men residing in Corpus Christi, Texas. Multivariate regression analyses were used to identify factors associated with receipt of thrombolytic therapy and to assess the association between receipt of thrombolytic therapy and mortality. During a 2-year period, 1199 patients hospitalized for myocardial infarction were identified; 159 (13.3%) received thrombolysis. Among "ideal" candidates for thrombolytic therapy, 74 (35.1%) of 211 received such therapy. Women were less likely to receive thrombolysis than men, and Mexican Americans were less likely to received thrombolysis than non-Hispanic whites. Patients for whom there was a delay of more than 4 hours between onset of symptoms and arrival at the hospital were also less likely to receive thrombolysis. Recipients of thrombolytic therapy experienced lower mortality over 56 months following myocardial infarction than did nonrecipients (20.5 versus 33.2%, P < 0.01). Use of thrombolytic therapy was less frequent among women and Mexican Americans than among men and non-Hispanic whites, and was limited by delay between onset of symptoms and arrival at the hospital.(ABSTRACT TRUNCATED AT 250 WORDS)

Predictors of 30-day mortality in the era of reperfusion for acute myocardial infarction. Results from an international trial of 41,021 patients. GUSTO-I Investigators

BACKGROUND

Despite remarkable advances in the treatment of acute myocardial infarction, substantial early patient mortality remains. Appropriate choices among alternative therapies and the use of clinical resources depend on an estimate of the patient's risk. Individual patients reflect a combination of clinical features that influence prognosis, and these factors must be appropriately weighted to produce an accurate assessment of risk. Prior studies to define prognosis either were performed before widespread use of thrombolysis or were limited in sample size or spectrum of data. Using the large population of the GUSTO-I trial, we performed a comprehensive analysis of relations between baseline clinical data and 30-day mortality and developed a multivariable statistical model for risk assessment in candidates for thrombolytic therapy.

METHODS AND RESULTS

For the 41,021 patients enrolled in GUSTO-I, a randomized trial of four thrombolytic strategies, relations between clinical descriptors routinely collected at initial presentation, and death within 30 days (which occurred in 7% of the population) were examined with both univariable and multivariable analyses. Variables studied included demographics, history and risk factors, presenting characteristics, and treatment assignment. Risk modeling was performed with logistic multiple regression and validated with bootstrapping techniques. Multivariable analysis identified age as the most significant factor influencing 30-day mortality, with rates of 1.1% in the youngest decile (< 45 years) and 20.5% in patients > 75 (adjusted chi 2 = 717, P < .0001). Other factors most significantly associated with increased mortality were lower systolic blood pressure (chi 2 = 550, P < .0001), higher Killip class (chi 2 = 350, P < .0001), elevated heart rate (chi 2 = 275, P < .0001), and anterior infarction (chi 2 = 143, P < .0001). Together, these five characteristics contained 90% of the prognostic information in the baseline clinical data. Other significant though less important factors included previous myocardial infarction, height, time to treatment, diabetes, weight, smoking status, type of thrombolytic, previous bypass surgery, hypertension, and prior cerebrovascular disease. Combining prognostic variables through logistic regression, we produced a validated model that stratified patient risk and accurately estimated the likelihood of death.

CONCLUSIONS

The clinical determinants of mortality in patients treated with thrombolytic therapy within 6 hours of symptom onset are multifactorial and the relations complex. Although a few variables contain most of the prognostic information, many others contribute additional independent prognostic information. Through consideration of multiple characteristics, including age, medical history, physiological significance of the infarction, and medical treatment, the prognosis of an individual patient can be accurately estimated.

How do smokers differ from nonsmokers in their response to thrombolysis? (the TIMI-4 trial)

Smokers with acute myocardial infarction appear to have a better outcome after thrombolysis than do nonsmokers. To identify factors that could contribute to this curious finding, we analyzed data from the Thrombolysis in Myocardial Infarction (TIMI-4) trial, in which 382 patients with acute myocardial infarction were randomized to tissue plasminogen activator, anistreplase, or both. Coronary angiography was performed 90 minutes and 18 to 36 hours after randomization, a myocardial perfusion scan was performed at 18 to 36 hours and before discharge, and a radionuclide ventriculogram was obtained before discharge. Angiographic and clinical outcome variables were determined in current smokers, ex-smokers, and nonsmokers, and regression analysis was used to correct for differences in baseline characteristics. The in-hospital mortality of current smokers was lower than that of ex-smokers and nonsmokers: 2.3% versus 5.2% versus 7.0%, respectively (p = 0.04 by paired comparison, current vs nonsmokers). Ninety minutes after randomization, the incidence of TIMI grade 3 flow was significantly higher in smokers than in ex-smokers and nonsmokers (55% vs 43% and 45%, p = 0.02); this difference was no longer observed at the second angiogram, nor did smokers differ from nonsmokers with respect to residual stenosis, thrombus grade, infarct size, ejection fraction, or recurrent ischemia. Because a strong inverse relation exists between TIMI grade 3 flow at 90 minutes and mortality, our findings suggest that the lower mortality of current smokers after thrombolytic therapy may be related to a higher incidence of early, complete reperfusion.

Reasons patients with chest pain delay or do not call 911

STUDY OBJECTIVE

To determine the reasons patients with suspected acute myocardial infarction (AMI) delay seeking medical care or do not call 911.

DESIGN

Telephone interview of patients hospitalized with suspected AMI.

SETTING

Nine hospitals in King County, Washington.

PARTICIPANTS

Patients admitted to a CCU or ICU between October 1, 1986, and December 31, 1987, with suspected AMI occurring out-of-hospital. Spouses of patients who met criteria but died during the hospitalization also participated.

INTERVENTIONS

Hospital records were reviewed, and a 20-minute telephone interview was conducted of patients who reside in King County but do not live in an extended care facility.

MEASUREMENTS

Patient demographics, cardiac history, symptoms, time of acute symptom onset, time of emergency department arrival, method of transportation, discharge diagnosis, and hospital outcome were abstracted from hospital records. Circumstances leading to the hospitalization, reasons for delay in seeking care, and reasons for not calling 911 were determined in the telephone interview.

RESULTS

In a 15-month period, 5,207 patients were hospitalized for suspected AMI in King County, Washington. Twenty-seven percent had AMI. Median patient delay between symptom onset and hospital arrival was 2 hours. Paramedics transported 45% of all patients. A representative subset of patients (2,316) were interviewed. The main reasons for delay were because the patient thought that the symptoms would go away, because the symptoms were not severe enough, and because the patient thought that the symptoms were caused by another illness. The main reasons for not calling 911 were because the symptoms were not severe enough, because the patient did not think of calling 911, and because the patient thought that self-transport would be faster because of his or her close location to the hospital.

CONCLUSION

Maximal benefit from thrombolytic therapy is not realized in a substantial proportion of patients with AMI because of delays in seeking medical care. Knowledge of the reasons patients delay or do not call 911 can help focus efforts on achieving more rapid treatment of patients with AMI.

Mortality within 24 hours of thrombolysis for myocardial infarction. The importance of early reperfusion. The GUSTO Investigators, Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries

BACKGROUND

A paradoxical increased risk of death has been reported during the first 24 hours after thrombolysis for myocardial infarction. The mechanism of this phenomenon is not known, nor is its relation to the success or failure of reperfusion. The present study was a prospectively designed analysis of deaths occurring within the first 24 hours in the GUSTO trial.

METHODS AND RESULTS

There were 41,021 patients enrolled in GUSTO, a randomized comparison of streptokinase with intravenous or subcutaneous heparin, accelerated tissue-type plasminogen activator (TPA), and combination of streptokinase and TPA. An angiographic mechanistic substudy examined reperfusion (using the TIMI flow grading criteria) 90 minutes after the assigned thrombolytic regimen was begun in 1567 patients. There were 1125 deaths (2.8%) within 24 hours ("early deaths") and 1726 additional deaths (4.2%) after 24 hours but within 30 days ("later deaths"). At the time of presentation, the most potent predictors of early death were hypotension and sinus tachycardia. In a multiple logistic regression model, lower systolic blood pressure, shorter height, higher heart rate, and the absence of prior smoking distinguished early death from later death. Reinfarction occurred in 26 patients (2.4%), shock in 572 patients (52%), atrioventricular block in 308 patients (28%), and tamponade in 106 patients (10%) dying early compared with 262 (15%), 788 (46%), 396 (23%), and 74 (4%) respective patients dying later. There were no differences in early mortality among the thrombolytic regimens for the first 6 hours after randomization. By 24 hours, however, mortality was 2.89% for streptokinase recipients, 2.84% for combination therapy recipients, and 2.36% for accelerated TPA recipients (P = .005). There was little difference among patients with differing flow grades in the infarct artery during the first 4 hours, although mortality was 2.35% for patients with flow grade 0 or 1, 2.92% for patients with flow grade 2, and 0.89% for patients with flow grade 3.

CONCLUSIONS

Even with aggressive management regimens, mortality within the first 24 hours accounted for a large proportion of postthrombolytic deaths. Patients dying early were more likely to present with pump failure than were those dying later and were more likely to diet of events related to left ventricular dysfunction, although cardiac tamponade also accounted for a significant minority of these deaths. Thus, the severity of the clinical presentation rather than the underlying risk factors predicts early mortality. Based on the angiographic substudy data, it appears that rather than hastening early mortality, successful restoration of complete antegrade flow in the infarct-related artery protects against early death.