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.

Comparisons of characteristics and outcomes among women and men with acute myocardial infarction treated with thrombolytic therapy. GUSTO-I investigators

OBJECTIVE

To compare baseline characteristics, complications, and treatment-specific outcomes of women and men with acute myocardial infarction treated with thrombolytic therapy.

DESIGN

Randomized controlled trial.

PATIENTS AND SETTING

A total of 10315 women and 30706 men with acute myocardial infarction treated in 1081 hospitals in 15 countries as part of the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO-I).

INTERVENTION

One of four thrombolytic regimens: (1) streptokinase with subcutaneous heparin; (2) streptokinase with intravenous heparin; (3) streptokinase plus alteplase (tissue-type plasminogen activator) with intravenous heparin; or (4) accelerated alteplase with intravenous heparin.

MAIN OUTCOME MEASURES

Mortality, stroke, and nonfatal complications during 30-day follow-up.

RESULTS

Women were on average 7 years older than men and delayed 18 minutes (median) longer after symptom onset before presenting to the hospital. After adjustment for age, women more often had a history of diabetes, hypertension, and smoking than men. Time to treatment was significantly longer in women (1.2 vs 1.0 hours; P<.001). Women had more nonfatal complications after treatment, including shock (9% vs 5%; P<.001), congestive heart failure (22% vs 14%; P<.001), serious bleeding (15% vs 7%; P<.001), and reinfarction (5.1% vs 3.6%; P<.001). Women had twice as many total strokes as men (2.1% vs 1.2%; P<.001), secondary to their older age at presentation. The unadjusted mortality rate was twice as high in women as men (11.3% vs 5.5%; P<.001); the relative risk (RR) of death was greater among women than men after adjustment for differences in baseline characteristics (RR=1.15; 95% confidence interval, 1.0 to 1.31). Although women and men underwent angiography at similar rates, there were small but significant differences in their rates of revascularization procedures (angioplasty: 35% of women and 32% of men; bypass surgery: 7% of women and 9% of men; P<.001 for both). The higher rate of stroke in women after treatment with alteplase (2.0% vs 1.9% with streptokinase and intravenous heparin) was offset by a greater relative reduction in mortality (10.3% vs 11.1%).

CONCLUSION

Women who received thrombolytic therapy for treatment of acute myocardial infarction were at greater risk for both fatal and nonfatal complications than men.

Early discharge in the thrombolytic era: an analysis of criteria for uncomplicated infarction from the Global Utilization of Streptokinase and t-PA for Occluded Coronary Arteries (GUSTO) trial

OBJECTIVES

This study sought to readdress the definition of uncomplicated myocardial infarction and to apply clinical criteria for early discharge of such patients in the thrombolytic era.

BACKGROUND

Previous studies proposed early hospital discharge at day 7 to 10 after acute myocardial infarction. The potential for earlier discharge of patients with uncomplicated infarction after thrombolysis remains undemonstrated.

METHODS

We defined "uncomplicated infarction" a priori as the absence of death, reinfarction, ischemia, stroke, shock, heart failure (Killip class > 1), bypass surgery, balloon pumping, emergency catheterization or cardioversion or defibrillation in the first 4 hospital days. We applied this definition to 41,021 patients in the Global Utilization of Streptokinase and t-PA for Occluded Coronary Arteries (GUSTO-I) trial. We examined death at 30 days and 1 year and rates of in-hospital reinfarction, heart failure, recurrent ischemia, shock and stroke in the uncomplicated and complicated groups created by application of our definition. We also assessed lengths of hospital and cardiac care unit stay.

RESULTS

Application of our clinical criteria yielded 23,497 (57.3%) patients in the uncomplicated group at day 4 with a very low risk of death and in-hospital complications: 30-day mortality 1%, reinfarction 1.7%, heart failure 2.6%, recurrent ischemia 6.7%, shock 0.4% and stroke 0.2%. One-year mortality was 3.6%. The median hospital stay was 9 days (7, 12 [25th, 75th percentiles, respectively]), and the median cardiac care unit stay 3 days (3, 5).

CONCLUSIONS

Simple clinical characteristics can identify a very low risk post-myocardial infarction population by hospital day 4. Use of these criteria for early discharge planning could substantially reduce length of stay for patients with uncomplicated acute myocardial infarction.

Randomized, double-blind, placebo-controlled dose-ranging study of tirofiban (MK-383) platelet IIb/IIIa blockade in high risk patients undergoing coronary angioplasty

OBJECTIVES

The objectives of this double-blind, placebo-controlled, randomized dose-ranging study were 1) to examine the safety and tolerability of tirofiban (MK-383), a new nonpeptide platelet IIb/IIIa receptor antagonist, on a background of intravenous heparin and aspirin therapy; 2) to study the pharmacodynamics and pharmacokinetics of tirofiban; and 3) to evaluate the incidence of adverse cardiac outcomes (urgent repeat revascularization, myocardial infarction and death) with tirofiban versus placebo in a high risk subset of patients undergoing coronary angioplasty.

BACKGROUND

Abrupt vessel closure complicates 4% to 8% of angioplasty procedures. Recent data have suggested that agents that antagonize the platelet glycoprotein IIb/IIIa receptor may reduce the incidence of adverse ischemic outcomes after coronary angioplasty.

METHODS

Seventy-three patients received tirofiban in three sequential dose panels and 20 patients received placebo. Patients within each panel were randomized to receive either tirofiban or placebo in a 3:1 randomization design. Bolus doses of 5, 10 and 10 microg/kg and continuous infusion (16 to 24 h) doses of 0.05, 0.10 and 0.15 microg/kg per min were administered in panels I, II and III, respectively. Patients received concomitant heparin and aspirin for the angioplasty procedure. Data on patients receiving placebo (heparin and aspirin only) were pooled across panels for comparisons. The pharmacodynamic effect of tirofiban on ex vivo platelet aggregation to 5 micromol/liter adenosine diphosphate (ADP) and bleeding times were measured. Clinical outcomes were assessed in all patients, but the power to detect clinically meaningful differences (a one-third reduction in clinical events) between groups was limited (5%).

RESULTS

Tirofiban was associated with a dose-dependent inhibition of ex vivo ADP-mediated platelet aggregation that was sustained during intravenous infusion and resolved rapidly after drug cessation. Adverse bleeding events, largely related to vascular access site hemorrhage, were slightly increased at the highest dose. Adverse clinical outcomes were infrequent in all patients and were not different among the small number of patients within each group.

CONCLUSIONS

This study establishes a rational and generally well tolerated dosing regimen for administration of tirofiban as adjunctive therapy in high risk angioplasty patients. The impact of tirofiban on adverse clinical outcomes after angioplasty awaits definition by a larger clinical trial.

A comparison of the treatment of acute myocardial infarction between St. Petersburg, Russia and Seattle, Washington

This study compared the baseline demographics, time to treatment and types of treatment of patients presenting with acute myocardial infarction in St. Petersburg, Russia and Seattle, WA. The study included 63 consecutive patients admitted to City Hospital #1 in St. Petersburg in July 1993. Comparative data for Seattle patients was obtained from the multi-year Myocardial Infarction Triage and Intervention project, a registry of all acute myocardial infarction patients hospitalized in the Seattle area. The results show a significantly prolonged time from symptom onset to presentation in Russia (51.8 h vs. 8.0 h; P < 0.001). Aspirin was used slightly more often in Seattle (78.9% vs. 74.6%; P = 0.40) while thrombolysis was used much more often in Seattle (22.5% vs. 6.3%; P = 0.002). There was also much less use of percutaneous transluminal coronary angioplasty (0% vs. 26.9%; P < 0.001), heparin (12.7% vs. 79.1%; P < 0.001), or cardiac catheterization (4.8% vs. 64.3%; P < 0.001). Also, the length of hospitalization was longer in St. Petersburg (23.8 +/- 10.8 vs. 7.5 +/- 5.1 days; P < 0.001). The findings in this study are an impetus for us all in understanding the magnitude of differences currently existing and the challenges for improving health care delivery in Russia.

Relation between symptom duration before thrombolytic therapy and final myocardial infarct size

BACKGROUND

Myocardial salvage is most likely to occur when thrombolytic therapy is administered within 4 to 6 hours of the onset of symptoms of myocardial infarction. The impact of delays within this early time period on final myocardial infarct size are unknown. The purpose of this study was to quantitate the relation between final myocardial infarct size and duration of symptoms before initiation of thrombolytic therapy in patients treated within 6 hours of symptom onset.

METHODS AND RESULTS

The findings from patients in four prospective randomized trials of thrombolytic therapy were combined for analysis. The study population consisted of 432 patients presenting within 6 hours of onset of symptoms of first acute myocardial infarction who met ECG criteria that allowed estimation of myocardial area at risk before treatment with thrombolytic therapy and who had thallium-201 myocardial infarct-size measurements performed several weeks after infarction. ECG analysis revealed no difference in myocardium at risk for infarction as a function of duration of symptoms before initiation of thrombolytic therapy. In contrast, univariate and multivariate analysis showed that final infarct size was highly dependent on duration of symptoms before initiation of therapy. Each 30-minute increase in symptom duration before thrombolytic therapy was associated with an increase in infarct size of 1% of the myocardium. Final infarct size in patients treated 4 to 6 hours after symptom onset was indistinguishable from patients who did not receive thrombolytic therapy.

CONCLUSIONS

These findings suggest that for patients treated within 4 to 6 hours of the onset of symptoms, there is a progressive decline in the extent of myocardium salvaged as the duration of symptoms before therapy increases. These results support efforts to minimize the time delay between symptom onset and initiation of reperfusion therapy in all eligible patients.

The influence of clinical risk factors on the use of angiography and revascularization after acute myocardial infarction. Myocardial Infarction Triage and Intervention Project Investigators

BACKGROUND

Coronary revascularization provides the greatest survival advantage in those patients with the greatest mortality risk. This study examines the relationship between variables that predict mortality and the use of angiography and revascularization after acute myocardial infarction.

METHODS

Study of 4823 survivors of acute myocardial infarction, who underwent angiography between 6 hours and 5 days of admission, to determine the relationship between factors that predict mortality and the use of angiography (n = 2274), angioplasty (n = 692), and bypass surgery (n = 469).

RESULTS

Except for recurrent angina, clinical factors that predict higher mortality were associated with a lower use of angiography (the multivariable adjusted odds ratio was 0.47 for older age, 0.85 for a history of infarction, 0.50 for patients not receiving thrombolytic medications, 0.64 for new heart failure, and 2.75 for recurrent angina [P < .001 for all factors]). A similar relationship was observed among patients selected for angioplasty (the odds ratio was 0.51 for an ejection fraction of < 40%, 0.72 for those patients not receiving thrombolytic medications, 0.74 for a history of infarction, and 1.94 for recurrent angina [P < .001 for all factors]). In contrast, patients with unfavorable prognostic profiles were much more likely to undergo coronary bypass surgery (the odds ratio was 1.46 for recurrent angina, 1.28 for older age groups, 2.23 for new heart failure, 1.28 for patients not receiving thrombolytic medications, and 1.46 for a history of infarction [P < .001 for all factors]).

CONCLUSIONS

These data suggest that aside from symptoms of recurrent angina, the use of angiography and angioplasty is not driven by mortality risk stratification. In contrast, bypass surgery is preferentially performed in patients at increased risk for mortality.

Stroke after thrombolysis. Mortality and functional outcomes in the GUSTO-I trial. Global Use of Strategies to Open Occluded Coronary Arteries

BACKGROUND

Stroke is the most feared complication of thrombolysis for acute myocardial infarction because of the resulting mortality and disability. We analyzed the incidence, timing, and outcomes of stroke in an international trial.

METHODS AND RESULTS

Patients were randomly assigned to one of four thrombolytic strategies. Neurological events were confirmed clinically and anatomically and were adjudicated by a blinded committee. Stroke survivors, categorized by residual deficit and disability, assessed their quality of life with a time trade-off technique. Multivariable regression identified patient characteristics associated with intracranial hemorrhage. Over-all, 1.4% of the patients had a stroke (93% anatomic documentation). The risk ranged from 1.19% with streptokinase/subcutaneous heparin therapy to 1.64% with combination thrombolytic therapy (P = .007). Primary intracranial hemorrhage rates ranged from 0.46% with streptokinase/subcutaneous heparin to 0.88% with combination therapy (P < .001). Of all strokes, 41% were fatal, 31% were disabling, and 24% were nondisabling, with no significant treatment-related differences. Stroke subtype affected prognosis: 60% of patients with primary intracranial hemorrhage died and 25% were disabled versus 17% dead and 40% disabled with nonhemorrhagic infarctions. Patients with moderate or severe residual deficits showed significantly decreased quality of life. Advanced age, lower weight, prior cerebrovascular disease or hypertension, systolic and diastolic blood pressures, randomization to tissue plasminogen activator, and an interaction between age and hypertension were significant predictors of intracranial hemorrhage.

CONCLUSIONS

Stroke remains a rare but catastrophic complication of thrombolysis. Additional studies should assess the net clinical benefit of thrombolysis in high-risk subgroups, particularly the elderly and patients with prior cerebrovascular events.

Clinical studies with the new glycosylated recombinant prourokinase

Recombinant prourokinase (r-ProUK) is a single-chain urokinase-type plasminogen activator that is produced from a mammalian cell line. It is administered as a zymogen and remains inactive until converted to the active two-chain form on the surface of a clot. The clot specificity of this agent, therefore, is conferred by the site of conversion to the active form on the surface of the clot. Two pilot studies were conducted to evaluate the safety and efficacy of r-ProUK in patients with acute myocardial infarction. In the first study, the 90-minute patency rate was 66.7% in 21 patients receiving 60 mg over 60 minutes and 72.2% in 18 patients receiving 60 mg over 90 minutes. In the second study, the 90-minute patency rates were 45.5% in the group primed with recombinant urokinase who were given 60 mg of r-ProUK infused over 60 minutes (11 patients) and 80.8% in the primed group given 60 mg infused over 90 minutes (26 patients). Only 4.6% of patients experienced severe bleeding complications, with no patient developing intracranial hemorrhage. These two studies describe the first application of r-ProUK in patients. Although two doses were selected for evaluation, the small number of patients studied did not permit the selection of one dose as superior to the other. The results, however, did indicate that r-ProUK is a very effective thrombolytic agent in achieving patency of occluded coronary arteries. It is especially effective in maintaining coronary patency, having shown only a 1.4% rate of reocclusion. Serious bleeding complications were few and no intracranial hemorrhages were noted in this group of 131 patients. Additional clinical trials will be needed to compare the efficacy of r-ProUK with that of other available thrombolytic agents.

Factors influencing the time to administration of thrombolytic therapy with recombinant tissue plasminogen activator (data from the National Registry of Myocardial Infarction). Participants in 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.

Regional variation across the United States in the management of acute myocardial infarction. GUSTO-1 Investigators. Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries

BACKGROUND

Differences in the management of acute myocardial infarction have been reported among countries, but few studies have investigated this issue in regions of the United States.

METHODS

We compared the management of acute myocardial infarction among census regions across the United States, using data from the first Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries trial (GUSTO-1) comprising 21,772 patients, and from the American Hospital Association.

RESULTS

We found substantial regional variation in the management of acute myocardial infarction in the United States. Beta-blockers (prescribed for a range of 55 to 81 percent of patients in the various regions), nitrates (prescribed for 61 to 77 percent), and angiotensin-converting-enzyme inhibitors (prescribed for 18 to 23 percent) were used most often in New England, whereas calcium-channel blockers (31 to 42 percent) and lidocaine (14 to 43 percent) were used least often there. Similarly, the proportion of patients undergoing various cardiac procedures differed among regions (range for angiography, 52 to 81 percent of patients; angioplasty, 22 to 35 percent; and coronary-artery bypass surgery, 9 to 17 percent) and was lowest in New England. The regional use of cardiac procedures was closely related to their availability, except in New England. After the analysis was adjusted for clinical and hospital variables, patients in New England were found to be less likely to undergo angiography than patients in the other regions (odds ratio, 0.37; 95 percent confidence interval, 0.32 to 0.42). There was no apparent relation between the use of cardiac procedures and rates of recurrent infarction or death at 30 days or 1 year.

CONCLUSIONS

There is substantial regional variation in the use of cardiac medications and procedures to manage acute myocardial infarction in the United States. The use and availability of cardiac procedures are closely related. The management of acute myocardial infarction in New England is atypical in that the relatively limited availability of cardiac procedures does not account for their relatively low use in that region.

Sequential combination thrombolytic therapy for acute myocardial infarction: results of the Pro-Urokinase and t-PA Enhancement of Thrombolysis (PATENT) Trial

OBJECTIVES

The present study was designed to test the efficacy and safety of a sequential combination of recombinant tissue-type plasminogen activator (rt-PA) and pro-urokinase in patients with acute myocardial infarction.

BACKGROUND

Efforts continue to identify a thrombolytic regimen that induces rapid, complete and sustained coronary artery patency in acute myocardial infarction. The two endogenous plasminogen activators rt-PA and pro-urokinase have been shown experimentally to induce fibrinolysis by sequential and complementary mechanisms. As a result, certain combinations of these activators have been found to be synergistic in vitro and in vivo.

METHODS

In a multicenter observational study with core facilities for angiographic and laboratory analysis, 101 patients with acute myocardial infarction were enrolled and given a low dose bolus of rt-PA (5 to 10 mg) followed by a 90-min infusion of pro-urokinase (40 mg/h). All patients received intravenous heparin and oral aspirin. Coronary angiography was performed in all patients at 90 min.

RESULTS

Angiography at 90 min showed the infarct-related artery to be patent (Thrombolysis in Myocardial Infarction [TIMI] grade 2 or 3 flow) in 77% of patients, and 60% achieved TIMI grade 3 flow. At one center, angiography was repeated at 24 h to detect a possible reocclusion. All 28 patients with a patent infarct-related artery at 90 min had patency at 24 h (82% achieved TIMI grade 3 flow). Treatment was well tolerated, with bleeding complications essentially confined to arterial puncture site hematomas. There was only one in-hospital death.

CONCLUSIONS

A sequential combination of low dose rt-PA and reduced-dose pro-urokinase produced a high TIMI 3 patency rate, was well tolerated and was associated with a low reocclusion rate.

Resource utilization in treatment of acute myocardial infarction: staff-model health maintenance organization versus fee-for-service hospitals. The MITI Investigators. Myocardial Infarction Triage and Intervention

OBJECTIVES

This study sought to compare the use of invasive procedures and length of stay for patients admitted with acute myocardial infarction to health maintenance organization (HMO) and fee-for-service hospitals.

BACKGROUND

The HMOs have reduced costs compared with fee-for-service systems by reducing discretionary admissions and decreasing hospital length of stay. It has not been established whether staff-model HMO hospitals also reduce the rate of procedure utilization.

METHODS

Using data from a retrospective cohort, we performed univariate and multivariate comparisons of the use of cardiac procedures, length of stay and hospital mortality in 998 patients admitted to two staff-model HMO hospitals and 7,036 patients admitted to 13 fee-for-service hospitals between January 1988 and December 1992.

RESULTS

The odds of undergoing coronary angiography were 1.5 times as great for patients admitted to fee-for-service hospitals than for those admitted to HMO hospitals (odds ratio 1.5, 95% confidence interval [CI] 1.3 to 1.9). Similarly, the odds of undergoing coronary revascularization were two times greater in fee-for-service hospitals (odds ratio 2.0, 95% CI 1.6 to 2.5). However, higher utilization was strongly associated with the greater availability of on-site cardiac catheterization facilities in fee-for-service hospitals. The length of hospital stay, by contrast, was approximately 1 day shorter in the fee-for-service cohort (7.3 vs. 8.0 days, p < 0.05).

CONCLUSIONS

Physicians in staff-model HMO hospitals use fewer invasive procedures and longer lengths of stay to treat patients with acute myocardial infarction than physicians in fee-for-service hospitals. This finding, however, appears to be associated with the lack of on-site catheterization facilities at HMO hospitals.

Streamlining the triage system for acute myocardial infarction

The full benefits of thrombolytic therapy can be realized if and only if treatment is delivered as quickly as possible. Streamlining the triage system will not only increase the numbers of patients treated with thrombolytic therapy, it will ultimately reduce mortality and morbidity rates from acute myocardial infarction by limiting loss of heart muscle. Reducing the time to treatment, however, is a daunting task given that both patient and hospital delays contribute to the underutilization or inefficient use of thrombolytic therapy. In particular, patient delays can be difficult to attenuate, given that human behavior is complex and that designing interventions to change behavior is not only challenging but expensive. Results from the MITI registry show that the emergency medical system is the linchpin of an efficient triage system in that it is associated with reduced patient delays as well as reduced treatment delays. Clearly, patients with chest pain need to be aware of the need to take prompt action by calling 911. On the other hand, decisions to use these systems to acquire electrocardiograms or deliver thrombolytic treatment will be faced by increasing numbers of administrators and policy makers in the years to come. Without adequate community support to maintain and improve these systems, the full benefits of thrombolytic therapy cannot be attained.

Time to thrombolytic treatment: factors affecting delay and their influence on outcome

One of the major limitations to realizing the full potential of the lifesaving effects of thrombolytic therapy has been the failure to initiate treatment in the first 1 to 1.5 h after symptom onset. The barriers to early treatment include the following: 1) Most patients fail to react rapidly and appropriately to symptoms. 2) Few emergency medical/paramedic systems have established effective triage systems for patients with chest pain or have implemented prehospital electrocardiography to better manage patients with possible acute myocardial infarction. 3) Time to treatment after hospital arrival currently averages 1 to 1.5 h-two to three times longer than what should be necessary to initiate therapy in the patient with typical electrocardiographic and clinical findings and co-morbid risk factors. Trials evaluating the effects of prehospital-initiated therapy have all shown trends toward a reduction in mortality (18%) associated with early treatment; however, none has been large enough in and of itself to be conclusive. The goal in the coming years will be to decrease each of these components of delay by developing effective education programs for the lay public, speeding and improving prehospital care by the routine use of electrocardiography and reducing hospital treatment times to < or = 30 min in the "uncomplicated" patient.

Outcomes in African-American women with suspected acute myocardial infarction: the Myocardial Infarction Triage and Intervention Project

Increasing attention has been given to the investigation of cardiovascular disease in women, although African-American women have received little attention. This study compares characteristics and outcomes in women admitted to coronary care units for suspected acute myocardial infarction (MI). Between January 1988 and December 1991, a total of 554 (5%) African-American and 9738 (95%) white women with suspected acute MI were admitted to coronary care units in metropolitan Seattle, Washington. Relevant demographic socioeconomic, clinical, and outcome data were abstracted from the medical record and entered in the Myocardial Infarction Triage and Intervention registry. African-American women were younger, more often single and unemployed, and were less likely to have health insurance than their white counterparts. In addition, a higher proportion of African-American women reported a history of hypertension and diabetes mellitus. After adjustment for age, African-American women were equally as likely to develop acute MI and were more likely to die in the hospital. In addition, a higher proportion of African-American women were readmitted to coronary care units for suspected MI. Compared with their white counterparts, African-American women with suspected acute MI were considerably worse off from both socioeconomic and clinical standpoints, and their relative disadvantage was apparent in poor outcomes.

Appearance of abnormal Q waves early in the course of acute myocardial infarction: implications for efficacy of thrombolytic therapy

OBJECTIVES

The purpose of this study was to determine the time course of the appearance of abnormal Q waves on the electrocardiogram (ECG) over the first 6 h of symptoms of myocardial infarction and to determine what implications, if any, such Q waves have for the efficacy of thrombolytic therapy.

BACKGROUND

Severe myocardial ischemia can produce early QRS changes in the absence of infarction. Abnormal Q waves on the baseline ECG may not be an accurate marker of irreversibly injured myocardium.

METHODS

Data from 695 patients who had no past history of myocardial infarction and whose admission ECG allowed prediction of myocardial infarct size in the absence of thrombolytic therapy (Aldrich score) were pooled from four prospective trials of thrombolytic therapy. The presence and number of abnormal Q waves on each patient's initial ECG were recorded. Four hundred thirty-six patients had left ventricular infarct size measured using quantitative thallium-201 tomography a mean (+/- SD) of 52 +/- 43 days after admission.

RESULTS

Of patients admitted within 1 h of symptoms, 53% had abnormal Q waves on the initial ECG. Both predicted and final infarct size were larger in patients with abnormal Q waves on the initial ECG independent of the duration of symptoms before therapy (p < 0.001). Despite this finding, the presence of abnormal Q waves on the admission ECG did not eliminate the effect of thrombolytic therapy on reducing final infarct size (p < 0.0001).

CONCLUSIONS

Abnormal Q waves are a common finding early in the course of acute myocardial infarction. However, there is no evidence that abnormal Q waves are associated with less benefit in terms of reduction of infarct size after thrombolytic therapy.

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.

ECG findings in acute myocardial infarction. Are there sex-related differences?

Women with acute myocardial infarction are less likely than men to receive thrombolytic therapy. It is not known whether sex-related differences in the presenting 12-lead electrocardiogram (ECG) account for this relative underutilization of acute reperfusion therapy in women. The authors examined the initial ECGs of 188 men and 185 women matched for age and history of previous acute myocardial infarction randomly selected from the Myocardial Infarction Triage and Intervention registry who presented with 4 hours of confirmed acute myocardial infarction. There were no sex-related differences in the number of leads with ST elevation, the presence of diagnostic ST elevation, or the overall magnitude of ST elevation. In addition, there was no sex-related difference in associated ECG findings that might effect physicians' utilization of acute reperfusion therapy, including the location of ST elevation (anterior vs inferior), the presence of abnormal Q waves in leads with ST elevation, the association of ST depression with ST elevation (reciprocal changes), or the presence of confounding factors, such as bundle branch block or hypertrophy. Differences in the presenting ECG do not explain the underutilization of acute reperfusion therapy in women.

Primary coronary angioplasty in hospitals with and without surgery backup. MITI project investigators

In the Myocardial Infarction Triage and Intervention (MITI) project, a registry of acute myocardial infarction, 1,062 patients were treated for acute myocardial infarction using primary coronary angioplasty. Of those, 470 (44%) received the procedure in hospitals without coronary surgery capability on-site. These patients were compared to 592 (56%) other patients treated in hospitals with on-site surgery. Most baseline characteristics of patients treated by primary angioplasty were similar in the two types of centers. ST segment elevation was present in 76% of patients; time from admission to angiography averaged 100 +/- 71 minutes (median 77 minutes). There was no difference in procedural success rate nor initial and long-term mortality rates in patients treated by primary angioplasty in the two types of hospitals. The mortality rate at discharge for patients treated by primary coronary angioplasty was 7% in both types of hospitals. In the subset of patients with ST segment elevation and no evidence of shock and no prior bypass surgery, 30 day mortality rates were 7% and 8% (p = 0.46), respectively. In a multivariable analysis of those factors influencing survival, age, a history of prior myocardial infarction, and anterior ST elevation but not the availability of on-site surgical backup, was associated with outcome. In summary, this observational study suggests that with appropriate patient selection, trained operators, and a provision for hospital transfer, primary coronary angioplasty can be accomplished in centers without on-site surgery with acceptable outcomes.

New recombinant glycosylated prourokinase for treatment of patients with acute myocardial infarction. Prourokinase Study Group

OBJECTIVES

Three dosage regimens of a new recombinant glycosylated prourokinase (A-74187) were evaluated by measuring coronary artery patency at 90 min in patients with acute myocardial infarction.

BACKGROUND

Prourokinase is a thrombolytic drug with unique pharmacologic properties that may be clinically advantageous.

METHODS

Aspirin (325 mg), intravenous heparin and prourokinase (60- or 80-mg monotherapy or 60 mg "primed" with a preceding bolus dose of 250,000 IU of recombinant urokinase) were administered to 128 patients. Coronary angiography was performed at 60 min (wherever possible), 90 min (primary end point) and 24 h to determine arterial patency and reocclusion rates. Plasma was collected serially to measure fibrinogen, plasminogen, thrombin antithrombin III and fibrinopeptide A. Clinical events until hospital discharge were recorded.

RESULTS

The coronary artery patency rate at 90 min was similar for all three regimens, averaging 73% (95% confidence interval [CI] 64% to 80%); Thrombolysis in Myocardial Infarction (TIMI) grade 3 flow rates averaged 52% (95% CI 42% to 61%). Arterial patency at 60 min was 62% (95% CI 50% to 73%), and reocclusion occurred in 1.4% (95% CI 0.1% to 4.1%). Prourokinase demonstrated relative fibrin specificity at all doses studied. Fibrinopeptide A and thrombin antithrombin III levels were elevated at baseline and declined rapidly during the 1st 12 h. There was no difference in the baseline values of these thrombin markers between patients with patent versus closed arteries at 90 min. There was one death; no strokes occurred.

CONCLUSIONS

A-74187 prourokinase is a rapid-acting, effective fibrin-specific thrombolytic agent. Reocclusion was unusual, possibly because of aggressive anticoagulation with intravenous heparin or unique features of the drug. Full definition of the clinical effectiveness of this drug merits examination in future randomized trials evaluating clinical and angiographic effectiveness.

Treatment of myocardial infarction in the United States (1990 to 1993). Observations from the National Registry of Myocardial Infarction

BACKGROUND

Multiple clinical trials have provided guidelines for the treatment of myocardial infarction, but there is little documentation as to how consistently their recommendations are being implemented in clinical practice.

METHODS AND RESULTS

Demographic, procedural, and outcome data from patients with acute myocardial infarction were collected at 1073 US hospitals collaborating in the National Registry of Myocardial Infarction during 1990 through 1993. Registry hospitals composed 14.4% of all US hospitals and were more likely to have a coronary care unit and invasive cardiac facilities than nonregistry US hospitals. Among 240,989 patients with myocardial infarction enrolled, 84,477 (35.1%) received thrombolytic therapy. Thrombolytic recipients were younger, more likely to be male, presented sooner after onset of symptoms, and were more likely to have localizing ECG changes. Among the 60,430 patients treated with recombinant tissue-type plasminogen activator (rTPA), 23.2% received it in the coronary care unit rather than in the emergency department. Elapsed time from hospital presentation to starting rTPA averaged 99 minutes (median, 57 minutes). Among patients receiving thrombolytic therapy, concomitant pharmacotherapy included intravenous heparin (96.9%), aspirin (84.0%), intravenous nitroglycerin (76.0%), oral beta-blockers (36.3%), calcium channel blockers (29.5%), and intravenous beta-blockers (17.4%). Invasive procedures in thrombolytic recipients included coronary arteriography (70.7%), angioplasty (30.3%), and bypass surgery (13.3%). Trend analyses from 1990 to 1993 suggest that the time from hospital evaluation to initiating thrombolytic therapy is shortening, usage of aspirin and beta-blockers is increasing, and usage of calcium channel blockers is decreasing.

CONCLUSIONS

This large registry experience suggests that management of myocardial infarction in the United States does not yet conform to many of the recent clinical trial recommendations. Thrombolytic therapy is underused, particularly in the elderly and late presenters. Although emerging trends toward more appropriate treatment are evident, hospital delay time in initiating thrombolytic therapy remains long, aspirin and beta-blockers appear to be underused, and calcium channel blockers and invasive procedures appear to be overused.