Laura J. Bowlby

Use of Reperfusion Therapy for Acute Myocardial Infarction in the United States Data From the National Registry of Myocardial Infarction 2

BACKGROUND There is clear evidence that reperfusion therapy improves survival in selected patients with an acute myocardial infarction. However, several studies have suggested that many patients with an acute myocardial infarction do not receive this therapy. Whether this underutilization occurs in patients appropriate for such therapy remains unclear. METHODS AND RESULTS We examined the use of reperfusion therapy in patients with an acute myocardial infarction hospitalized at 1470 hospitals participating in the National Registry of Myocardial Infarction 2. We identified 84 663 patients who were eligible for reperfusion therapy as defined by diagnostic changes on the initial 12-lead ECG, presentation to the hospital within 6 hours from symptom onset, and no contraindications to thrombolytic therapy. Twenty-four percent of these eligible patients did not receive any form of reperfusion therapy (7.5% of all patients). When multivariate analyses were used, left bundle-branch block (odds ratio [OR]=0.22; 95% CI=0.20 to 0.24), lack of chest pain at presentation (OR=0.22; 95% CI=0.21 to 0.24), age >75 years (OR=0.40, 95% CI=0.36 to 0.43), female sex (OR=0.88, 95% CI=0.83 to 0.92), and various preexisting cardiovascular conditions were independent predictors that the patient would not receive reperfusion therapy. CONCLUSIONS Reperfusion therapy may be underutilized in the United States. Increased use of reperfusion therapy could potentially reduce the unnecessarily high mortality rates observed in women, the elderly, and other patient groups with the highest risk of death from an acute myocardial infarction.

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.

The prehospital electrocardiogram in acute myocardial infarction : Is its full potential being realized?

OBJECTIVES This study sought to examine the management and subsequent outcomes of patients with a prehospital electrocardiogram (ECG) in a large, voluntary registry of myocardial infarction. BACKGROUND The prehospital ECG has been proposed as a means of rapidly identifying patients with acute myocardial infarction who might be eligible for reperfusion therapy. METHODS The characteristics and outcomes of patients with a prehospital ECG were compared with those without a prehospital ECG in the National Registry of Myocardial Infarction 2 data base. Included in the analysis were those patients who presented to the hospital within 12 h of an acute myocardial infarction. Excluded were patients with an in-hospital infarction, transferred-in referrals and self-transported patients. RESULTS Prehospital ECGs were obtained in 3,768 (5%) of 66,995 National Registry of Myocardial Infarction 2 patients meeting study criteria. Median time from myocardial infarction symptom onset until hospital arrival was longer among those having a prehospital ECG (152 vs. 91 min, p < 0.001). However, once in the hospital, the prehospital ECG group experienced a shorter median time to the initiation of either thrombolysis (30 vs. 40 min, p < 0.001) or primary angioplasty (92 vs. 115 min, p < 0.001). The prehospital ECG group was more likely to receive thrombolytic therapy (43% vs. 37%, p < 0.001) and to undergo primary angioplasty (11% vs. 7%, p < 0.001). Also, the prehospital ECG group was more likely to undergo coronary arteriography (55% vs. 40%, p < 0.001), angioplasty (24% vs. 16%, p < 0.001) or bypass surgery (10% vs. 6%, p < 0.001). The in-hospital mortality rate was 8% in patients with a prehospital ECG and 12% in those without a prehospital ECG (p < 0.001). After adjusting for baseline covariates utilizing multiple logistic regression analysis, this mortality difference remained statistically significant (odds ratio 0.83, 95% confidence interval 0.71 to 0.96, p = 0.01). CONCLUSIONS The prehospital ECG is infrequently utilized for diagnosing myocardial infarction, and among patients with a prehospital ECG, is associated with a longer time from symptom onset to hospital arrival. Despite these shortcomings, the prehospital ECG is a test that may potentially influence the management of patients with acute myocardial infarction through wider, faster in-hospital utilization of reperfusion strategies and greater usage of invasive procedures, factors that may possibly reduce shortterm mortality. Efforts to implement the prehospital ECG more widely and more rapidly may be indicated.

Factors influencing the time to administration of thrombolytic therapy with recombinant tissue plasminogen activator (data from the national registry of myocardial infarction)

Very early administration of thrombolytic therapy for acute myocardial infarction (AMI) has significantly reduced mortality in eligible patients. The purpose of this study was to evaluate factors which influenced the time from symptom onset to hospital presentation and the time from hospital presentation to the onset of thrombolytic treatment in a large population of patients with AMI. This study included 212,990 patients from 904 hospitals that participated in the National Registry of Myocardial Infarction. The median time from symptom onset to hospital presentation for those treated was 1.5 hours versus 2.7 hours for those not receiving thrombolytic treatment. Older patients and women had increased delay times, as did those who arrived at the hospital during daytime hours. Of the 59,802 (28%) patients who received thrombolytic treatment, 23% were treated < 30 minutes from admission; 63%, < 60 minutes; and 83%, < 90 minutes. Time to treatment increased with age and was longer for women and for patients arriving between midnight and early morning. The most important factor associated with shorter time to treatment was the initiation of thrombolytic treatment in the emergency department rather than in the coronary care unit (47 vs 73 minutes, p < 0.0001). Hospital treatment times are much too long, given that quick identification and treatment of eligible patients are of primary importance in reducing mortality from AMI. To shorten these times, thrombolytic treatment should be initiated in the emergency department, and the effectiveness of hospital programs aimed at reducing time to treatment should be subject to continuing quality improvement surveillance.

Hospital protocols and policies that may delay early identification and thrombolytic therapy of acute myocardial infarction patients

Despite the compelling relationship between early treatment and outcome from reperfusion therapy in patients with acute myocardial infarction, significant delays in early treatment are imposed by the patient, prehospital systems, and hospital processes and protocols used in the identification and treatment of patients with myocardial infarction. A survey instrument designed to determine the prevalence of hospital policies and protocols that might delay or expedite treatment with thrombolytic therapy in patients with acute myocardial infarction was completed by 524 hospitals participating in the National Registry for Myocardial Infarction (NRMI). Participating hospitals had treated 17,646 patients with tissue plasminogen activator. The door to drug time for the entire population of patients treated at each hospital was available. Door to drug times were compared between those hospitals that had a positive response to a policy and those that had a negative response to that policy. Among respondent hospitals, thrombolysis was excluded by protocol in 34.4% for age above 75 and in 55% for presentation after 6 hours of chest pain onset. Furthermore, 29.4% of hospitals required routine laboratory testing other than electrocardiography (ECG), including chest x-ray, prior to determination of eligibility for thrombolysis. Door to drug times were shorter in those hospitals with prehospital 12-lead ECG availability, assessment of the 12-lead ECG by the emergency department nurse and physician as soon as it was available, and initiation of thrombolysis by the emergency physician (in patients with clear-cut ST elevation myocardial infarction) without bedside cardiology consultation. Door to drug times were longer in those hospitals in which predecision laboratory results were required, written informed consent was mandated, and drug was initiated in the cardiac intensive care unit rather than in the emergency department itself. Door to drug times were not significantly different in those hospitals with a designated chest pain center compared with those operating under a focused patient care protocol. We conclude that the earliest possible hospital treatment of acute myocardial infarction patients may be precluded by multiple components of emergency department policies and process, many of them inappropriate for safe, efficient, and effective identification and management of these patients.