ACC/AHA guidelines for the early management of patients with acute myocardial infarction. A report of the American College of Cardiology/American Heart Association Task Force on Assessment of Diagnostic and Therapeutic Cardiovascular Procedures (subcommittee to develop guidelines for the early management of patients with acute myocardial infarction)

Decade-long trends (1986 to 1997) in the medical treatment of patients with acute myocardial infarction: A community-wide perspective

BACKGROUND

Although there are an increasing number and variety of medications available for the treatment of patients with acute myocardial infarction (AMI), few data are available describing recent, and changes over time in, use of different cardiac medications in patients with AMI from a more generalizable, community-wide perspective. Moreover, it is unclear whether the demographic and clinical profile of patients receiving these agents is similar or varies according to the type of agent prescribed.

METHODS AND RESULTS

The purpose of this study was to examine recent patterns and changes over a decade-long period (1986 to 1997) in the use of cardiac medications during the acute hospitalization and at the time of hospital discharge in metropolitan Worcester, Mass, residents (1990 census estimate, 437,000) hospitalized with confirmed AMI. There was a marked increase in the use of angiotensin-converting enzyme inhibitors, aspirin, beta-blockers, lipid-lowering agents, and thrombolytic therapy between 1986 and 1997. The use of calcium antagonists, lidocaine, and other antiarrhythmic agents declined over this period. Similar trends were observed in the use of these agents in hospital survivors at the time of hospital discharge. Patient age, presence of comorbidities, and AMI-associated characteristics influenced the use of these therapies; sex differences in the use of several of these medications were also noted.

CONCLUSIONS

The results of this population-based observational study provide insights into changing prescribing patterns in the hospital treatment of patients with AMI. Despite encouraging increases in the use of several of these agents, considerable opportunities for increased utilization remain.

Comparison of early invasive and conservative strategies in patients with unstable coronary syndromes treated with the glycoprotein IIb/IIIa inhibitor tirofiban

BACKGROUND

There is continued debate as to whether a routine, early invasive strategy is superior to a conservative strategy for the management of unstable angina and myocardial infarction without ST-segment elevation.

METHODS

We enrolled 2220 patients with unstable angina and myocardial infarction without ST-segment elevation who had electrocardiographic evidence of changes in the ST segment or T wave, elevated levels of cardiac markers, a history of coronary artery disease, or all three findings. All patients were treated with aspirin, heparin, and the glycoprotein IIb/IIIa inhibitor tirofiban. They were randomly assigned to an early invasive strategy, which included routine catheterization within 4 to 48 hours and revascularization as appropriate, or to a more conservative (selectively invasive) strategy, in which catheterization was performed only if the patient had objective evidence of recurrent ischemia or an abnormal stress test. The primary end point was a composite of death, nonfatal myocardial infarction, and rehospitalization for an acute coronary syndrome at six months.

RESULTS

At six months, the rate of the primary end point was 15.9 percent with use of the early invasive strategy and 19.4 percent with use of the conservative strategy (odds ratio, 0.78; 95 percent confidence interval, 0.62 to 0.97; P=0.025). The rate of death or nonfatal myocardial infarction at six months was similarly reduced (7.3 percent vs. 9.5 percent; odds ratio, 0.74; 95 percent confidence interval, 0.54 to 1.00; P<0.05).

CONCLUSIONS

In patients with unstable angina and myocardial infarction without ST-segment elevation who were treated with the glycoprotein IIb/IIIa inhibitor tirofiban, the use of an early invasive strategy significantly reduced the incidence of major cardiac events. These data support a policy involving broader use of the early inhibition of glycoprotein IIb/IIIa in combination with an early invasive strategy in such patients.

Improved treatment of coronary heart disease by implementation of a Cardiac Hospitalization Atherosclerosis Management Program (CHAMP)

Despite scientific evidence that secondary prevention medical therapies reduce mortality in patients with established coronary artery disease, these therapies continue to be underutilized in patients receiving conventional care. To address this issue, a Cardiac Hospital Atherosclerosis Management Program (CHAMP) focused on initiation of aspirin, cholesterol-lowering medication (hydroxymethylglutaryl coenzyme A [HMG CoA] reductase inhibitor titrated to achieve low-density lipoprotein [LDL] cholesterol < or =100 mg/dl), beta blocker, and angiotensin-converting enzyme (ACE) inhibitor therapy in conjunction with diet and exercise counseling before hospital discharge in patients with established coronary artery disease. Treatment rates and clinical outcome were compared in patients discharged after myocardial infarction in the 2-year period before (1992 to 1993) and the 2-year period after (1994 to 1995) CHAMP was implemented. In the pre- and post-CHAMP patient groups, aspirin use at discharge improved from 68% to 92% (p <0.01), beta blocker use improved from 12% to 62% (p <0.01), ACE inhibitor use increased from 6% to 58% (p <0.01), and statin use increased from 6% to 86% (p <0.01). This increased use of treatment persisted during subsequent follow-up. There was also a significant increase in patients achieving a LDL cholesterol < or =100 mg/dl (6% vs 58%, p <0.001) and a reduction in recurrent myocardial infarction and 1-year mortality. Compared with conventional guidelines and care, CHAMP was associated with a significant increase in use of medications that have been previously demonstrated to reduce mortality; more patients achieved an LDL cholesterol < or =100 mg/dl, and there were improved clinical outcomes in patients after hospitalization for acute myocardial infarction.

Medical treatment for acute coronary syndromes

The medical treatment of acute coronary syndromes with thrombolytic, antithrombin, and antiplatelet agents is a major area of research and a vast topic for clinical review. This review summarizes important recent findings on the background of existing pathological and clinical knowledge to provide an understanding of the basis of current therapy and the new therapies that are likely to be introduced in the near future. Current controversies regarding the management of these conditions and the choice between medical, interventional, and combined strategies in different situations are also discussed.

Effects of potassium channel opener KRN4884 on human conduit arteries used as coronary bypass grafts

AIMS

The effects of a new potassium channel opener KRN4884 on human arteries have not been studied. This study was designed to investigate the effects of KRN4884 on the human internal mammary artery (IMA) in order to provide information on possible clinical applications of KRN4884 for preventing and relieving vasospasm of arterial grafts in coronary artery bypass grafting.

METHODS

IMA segments (n = 140) taken from patients undergoing coronary surgery were studied in the organ chamber. Concentration-relaxation curves for KRN4884 were established in the IMA precontracted with noradrenaline (NA), 5-hydroxytryptamine (5-HT), angiotensin II (ANG II), and endothelin-1 (ET-1). The effect of glibenclamide (GBC) on the KRN4884-induced relaxation was also examined in NA or 5-HT-precontracted IMA. Concentration-contraction curves for the four vasoconstrictors were constructed without/with pretreatment of KNR4884 (1 or 30 microM) for 15 min.

RESULTS

KRN4884 induced less relaxation (P < 0.05) in the precontraction induced by ET-1 (72.9 +/- 5.5%) than by ANG II (94.2 +/- 3.2%) or NA (93.7 +/- 4.1%) with lower EC50 (P < 0.05) for ANG II (-8.54 +/- 0.54 log M) than that for NA (-6.14 +/- 0.15 log M) or ET-1 (-6.69 +/- 0.34 log M). The relaxation in the IMA pretreated with GBC was less than that in control (P < 0.05). KRN4884-pretreatment significantly reduced the contraction (P < 0.05) induced by NA (151.3 +/- 18.4% vs 82.7 +/- 8. 7%), 5-HT (82.7 +/- 12.2% vs 30.1 +/- 7.3%), and ANG II (24.3 +/- 6. 3% vs 5.4 +/- 1.6%), but did not significantly reduce the contraction induced by ET-1 (P > 0.05).

CONCLUSION

KRN4884 has marked vasorelaxant effects on the human IMA contracted by a variety of vasoconstrictors and the effect is vasoconstrictor-selective.

CME Paper: Acute Myocardial Infarction in the Elderly

Up to half of admissions with myocardial infarction are over 70 years of age. Mortality in this age group is higher than in younger age groups. However, elderly patients are less likely to be managed in an acute coronary care setting. Low dose aspirin should be given to all elderly patients with myocardial infarction. Thrombolytic agents have the greatest effect in the elderly even though they give an increased risk of hemorrhagic stroke. They are underused in the elderly with myocardial infarction for a number of reasons. Ã -Blockers reduce mortality post infarction and ACE inhibitors improve morbidity and mortality rates in those with evidence of heart failure post infarction. Amiodarone may also be of use as an antiarrhythmic in the post infarction period. (c) 2000 by CVRR, Inc.

Prehospital delay in patients hospitalized with heart attack symptoms in the United States: the REACT trial. Rapid Early Action for Coronary Treatment (REACT) Study Group

BACKGROUND

The use of thrombolytic therapy for patients with myocardial infarction has been limited by patient delay in seeking care. We sought to characterize prehospital delay in patients hospitalized for evaluation of heart attack symptoms.

METHODS AND RESULTS

The Rapid Early Action for Coronary Treatment (REACT) is a multicenter, randomized community trial designed to reduce patient delay. At baseline, data were abstracted from the medical records of 3783 patients hospitalized for evaluation of heart attack symptoms in 20 communities. The median prehospital delay was 2.0 hours; 25% of patients delayed longer than 5.2 hours. In a multivariable analysis, delay time was longer among non-Hispanic blacks than among non-Hispanic whites, longer at older ages, longer among Medicaid-only recipients and shorter among Medicare recipients than among privately insured patients, and shorter among patients who used an ambulance.

CONCLUSIONS

The observed pattern of differences is consistent with the contention that demographic, cultural, and/or socioeconomic barriers exist that impede rapid care seeking.

Knowledge, patterns of care, and outcomes of care for generalists and specialists

OBJECTIVE

To critically evaluate the differences between generalist physicians and specialists in terms of knowledge, patterns of care, and clinical outcomes of care.

METHODS

English-language articles (January 1981 to January 1998) were identified through a Medline search and examination of bibliographies of identified articles. Systematic evaluation of articles relevant to adult medicine that had a direct comparison between generalist physicians and specialists in terms of knowledge relative to widely accepted standards of care, patterns of care (including use of medications, ancillary services, procedures, and resource utilization), and outcomes of care was performed.

MAIN RESULTS

In many survey studies, specialists were reported to be more knowledgeable about conditions encompassed within their specialty. In terms of overall practice patterns, specialists practicing in their area of expertise were more likely to use medications associated with improved survival and to comply with routine health maintenance screening guidelines; they used more resources including diagnostic tests, procedures, and longer hospital stays. In the limited number of studies examining the care of patients with acute myocardial infarction, acute nonhemorrhagic stroke, and asthma, specialists had superior outcomes compared with generalists.

CONCLUSIONS

There is evidence in the literature suggesting differences between specialists and generalists in terms of knowledge, patterns of care, and clinical outcomes of care for a broad range of diseases. In published studies, specialists were generally more knowledgeable about their area of expertise and quicker to adopt new and effective treatments than generalists. More research is needed to examine whether these patterns of care translate into superior outcomes for patients. Further work is also needed to delineate the components of care for which generalists and specialists should be responsible, in order to provide the highest quality of care to patients while most effectively utilizing existing physician manpower.

Emergent right coronary artery thrombectomy with a jet aspiration thrombectomy catheter

A saline-jet aspiration thrombectomy (JAT) catheter was used in a patient with acute myocardial infarction. A right coronary arteriogram showed complete thrombotic occlusion at the proximal segment. With this catheter the thrombus was removed without complications in 5 sec. The patient underwent percutaneous transluminal coronary angioplasty and placement of a Palmaz-Schatz stent after successful thrombectomy. Thrombectomy with a JAT catheter was very useful in this patient.

Comparison of the vasorelaxant effect of nitroprusside and nitroglycerin in the human radial artery in vitro

AIMS

In recent years the radial artery (RA) has been re-introduced for coronary artery bypass grafting (CABG). However, the potential for vasospasm remains a clinical problem when this vessel is employed and effective vasodilator agents are required to combat vasospastic events. This in vitro study was designed to compare the vasodilator effects of sodium nitroprusside (SNP) and nitroglycerin (NTG) in the human RA.

METHODS

Human RA segments (n=70) were taken from vessels employed for grafting in patients undergoing CABG. Concentration-relaxation curves for SNP and NTG were established in RA which had been precontracted with various vasoconstrictors (potassium chloride [K+], the thromboxane A2 mimetic agent U46619 or endothelin-1 [ET-1]).

RESULTS

Both SNP and NTG caused complete relaxation and EC50s were similar except that NTG was 6.2-fold more potent than SNP in U46619-induced contraction (-7.50+/-0.16 vs -6. 71+/-0.38 log m, P=0.04). After treatment with verapamil and NTG solution during harvesting, the RA segments responded with reduced maximal relaxation to NTG (84.9+/-3.9%, compared with 98.8+/-0.8% in the control, P=0.004). The vessel became less sensitive to NTG (EC50: -6.29+/-0.4 vs -7.50+/-0.16 log m, P=0.01). In investigations carried out with SNP, tolerance was only seen in the magnitude of the relaxation (87.4+/-4.7% vs 99.2+/-0.6% in the control, P=0.03).

CONCLUSIONS

Both NTG and SNP are potent vasodilators in the RA. NTG may have more potent effects in certain situations (constriction related to thromboxane A2). However, tolerance to NTG may develop. A cross tolerance to SNP may exist but the effect is weak so that SNP may be preferable to NTG as a vasodilator in the RA postoperatively. Other vasodilators may be the drugs of choice under such circumstances.

In vitro skin permeation of Sinitrodil, a member of a new class of nitrovasodilator drugs

Clinical trials have shown the potential of benzoxazinones, a new class of organic nitrates, in cardiovascular therapy. In particular Sinitrodil possesses a coronary vascular selectivity greater than that of Nitroglycerin and isosorbide dinitrate. The objective of this study was a preliminary evaluation of the ability of these new organic nitrate derivatives to reach therapeutical steady-state plasma concentrations following a transdermal administration. In vitro permeation studies through human stratum corneum and epidermis have been conducted on two members of this class: Sinitrodil (ITF 296) and ITF 1129. Comparative studies have also been carried out with Nitroglycerin, Isosorbide dinitrate and Nicorandil. Two different fixed concentrations were tested: 0.08% w/v solution and saturated solution. Sinitrodil could be considered a good candidate for transdermal administration on the basis of the in vitro permeation results and of the known therapeutical plasma concentration.

SHould we emergently revascularize Occluded Coronaries for cardiogenic shocK: an international randomized trial of emergency PTCA/CABG-trial design. The SHOCK Trial Study Group

BACKGROUND

Cardiogenic shock (CS) is the leading cause of death in patients hospitalized with acute myocardial infarction (MI). Nonrandomized studies suggest reduced mortality rate with revascularization.

TRIAL DESIGN

The SHOCK trial is a multicenter, randomized, and unblinded study with a Registry for trial-eligible and ineligible nonrandomized patients. The trial is testing the hypothesis that a direct invasive strategy of emergency revascularization for patients with cardiogenic shock complicating acute MI will reduce 30-day all-cause mortality rate by 20 absolute percentage points compared with initial medical stabilization. Eligibility criteria include development of CS within 36 hours of an acute transmural MI as evidenced by ST elevation or new left bundle branch block MI; clinical criteria for CS with hemodynamic confirmation; absence of a mechanical, iatrogenic, or other cause of shock; and enrollment within 12 hours of CS diagnosis. Patients randomly assigned to emergency revascularization immediately undergo coronary angiography, with percutaneous transluminal coronary angioplasty or coronary artery bypass grafting depending on the coronary anatomy. Patients assigned to initial medical stabilization may undergo revascularization >/=54 hours after randomization.

END POINTS

The primary end point is all-cause 30-day mortality after randomization. Secondary end points include death at trial termination, changes in left ventricular dimensions and function measured by echocardiography at randomization and 2 weeks later, and changes in quality of life and physical functioning from 2 weeks after discharge to 6 months after MI.

Intravenous beta-blockers in acute myocardial infarction: perceived versus actual use by cardiologists and emergency physicians

This study sought to determine the relationship between perceived and actual use of intravenous beta-blockers by cardiologists and emergency physicians for patients with acute myocardial infarction (AMI). The charts of 35 patients who presented to the emergency department of a community hospital with AMI during a 6-month period were retrospectively reviewed. Members of the departments of cardiology and emergency medicine were mailed a one-page survey pertaining to their use of intravenous beta-blockers in AMI. Of the 35 patients only 4 (11%) received an intravenous beta-blocker. Three of these 4 patients were either hypertensive or tachycardic and none had a contraindication to beta-blockade. A contraindication was present in 15 (48%) of those who did not get intravenous beta-blockade. The survey was completed by 11 (100%) of the emergency physicians and 68 (69%) of the cardiologists. Emergency physicians were significantly less likely to report using intravenous beta-blockers in AMI patients who were normotensive with normal heart rates (P=.007) and most (9 of 11) deferred the decision to the cardiologist. Although the majority of cardiologists reported giving an intravenous beta-blocker to at least 50% of AMI patients with normal blood pressure and pulse rates, the actual frequency was only 8% (1 of 13). In this institution, cardiologists overestimated the frequency of intravenous beta-blocker administration to patients with AMI. Emergency physicians usually deferred the decision on intravenous beta-blockers to cardiologists and reported a frequency of use that was much closer to actual practice.

Tetranectin levels in patients with acute myocardial infarction and their alterations during thrombolytic treatment

Tetranectin (TN), a new regulator of fibrinolysis, was studied in the plasma of 60 patients with acute myocardial infarction (AMI) and 30 healthy subjects (HS), in relation to D-dimer (DD) and alpha 2-plasmin inhibitor (alpha 2-PI), to investigate its possible involvement in the pathophysiology of AMI. Thirty patients underwent thrombolytic treatment with fibrin-specific plasminogen activator (rt-PA) (group A); the other 30 patients, according to the exclusion criteria, were conventionally treated (group B). Twenty of the thrombolysized patients established early recanalization (subgroup A1), while 10 failed to respond to thrombolytic treatment (subgroup A2). Median (interquartile range), baseline plasma TN levels were lower in AMI patients compared to HS [8.27 (2.75) mg/L versus 12.1 (0.55) mg/L, P < 10(-6)]. In subgroup A1, TN increased at the end of rt-PA infusion and returned to the baseline levels 12 h later. A positive association between DD and TN release (3 h level minus baseline level) was found (rs = 0.48, P = 0.03) in subgroup A1. No significant alterations of TN levels were observed during therapy in subgroup A2 and group B. TN, DD and alpha 2-PI concentrations in group B remained relatively constant during the study period. This study provides evidence of a significant decrease of TN levels in AMI patients compared to healthy subjects and of a remarkable difference in the evolution of TN levels during thrombolytic treatment with rt-PA between recanalized and non-recanalized AMI patients. Thus, an involvement of TN in the formation and dissolution of fibrin clot in AMI patients is worthy of further investigation.

Development of new methods to assess the outcomes of emergency care

This article provides information supporting the need for new outcome measures in emergency care. It also addresses the use of outcome measures in emergency care, the impact of emergency care, identification of at-risk groups, new approaches to measuring patient satisfaction, quality of life and cost-effectiveness, and the unique related implications for emergency medicine.

Development of new methods to assess the outcomes of emergency care

This article provides information supporting the need for new outcome measures in emergency care. It also addresses the use of these measures in emergency care, the impact of emergency care, identification of at-risk groups, new approaches to measuring patient satisfaction, quality of life, and cost-effectiveness, and the related unique implications for emergency medicine.

Thrombosis and Hemostasis in Cardiology: Review of Pathophysiology and Clinical Practice (Part I)

The adverse consequences of thrombosis are per haps nowhere more evident than in clinical cardiology. Throm bosis and hemostasis are primary issues in the management of patients with atrial fibrillation, prosthetic heart valves, severe left ventricular dysfunction, and coronary artery disease. Clini cal trials have defined a crucial role for anticoagulation with warfarin in patients with atrial fibrillation to reduce the inci dence of stroke. Anticoagulation with warfarin and aspirin in combination offers significant protection from systemic emboli in patients with mechanical prosthetic valves, without a sub stantial increased risk of hemorrhage. The risk of systemic emboli may also be reduced by anticoagulation in patients with severe left ventricular dysfunction. Disturbance of the normal balance of hemostasis is a major factor in the pathophysiology of coronary artery disease. Antiplatelet therapy, antithrombin agents, anticoagulants, and fibrinolytic agents have been used to prevent and treat acute coronary thrombosis and to prevent reocclusion following thrombolysis and interventional therapy. Guidelines are presented for antithrombotic therapy in the prac tice of clinical cardiology.

Effect of beta-adrenergic blocking agents on mortality rate in patients not revascularized after myocardial infarction: data from a large HMO

We investigated whether patients who do not undergo coronary angiography and therefore any form of revascularization after a myocardial infarction derive greater benefit from chronic beta-blocker therapy than patients who undergo coronary angiography. With multivariate analyses, treatment with beta-blockers was a much stronger predictor of survival in patients who did not undergo coronary angiography (relative risk = 0.38, p = 0.005) than in those patients who did undergo catheterization (p < 0.05 for interaction). Our findings provide direct support for the recommendation by the American College of Cardiology/American Heart Association task force that beta-blocker therapy should be initiated for all infarct survivors who do not undergo revascularization and who have no contraindications.

The evolution of today's hospital emergency departments--current problems and challenges

The announcement of the National Heart Attack Alert Program by the National Heart, Lung and Blood Institute in June of 1991 prompted leaders of the Florida Chapter of the American College of Cardiology to develop a statewide program to reduce the morbidity and mortality from acute myocardial infarctions within Florida. It became apparent that the success of such a program would require the prompt institution of thrombolytic agent or other revascularization procedures in appropriate patients. No longer could the decision regarding institution of therapy await discussion by telephone and/or the arrival at the emergency department (ED) of the patient's primary care physician or cardiologist. Efforts to establish appropriate protocols for therapy revealed that many of the 25,000 or more physicians currently staffing the 5,600 or so EDs in this country were moonlighting residents or practitioners from a variety of specialties or subspecialties with limited or no formal EM training. Furthermore, it was learned that there were in the entire country only about 800 postgraduate, year-one Council for Graduate Medical Education accredited training positions. There were only 21 such training positions in the entire state of Florida. The reasons for these deficiencies are discussed and a challenge to correct this person power crisis is issued, not principally to the leadership of EM, but to the entire medical profession.

Determinants of the use of coronary angiography and revascularization after thrombolysis for acute myocardial infarction

BACKGROUND

Clinical trials and practice guidelines have identified clinical criteria for the use of coronary angiography and revascularization procedures after thrombolysis for acute myocardial infarction. The effect of these criteria on clinical practice has not been extensively evaluated.

METHODS

We used classification-and-regression-tree (CART) and logistic-regression models to study the patients in the first Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries trial, to identify the variables that best predicted the use of angiography and revascularization procedures after thrombolysis.

RESULTS

Among the 21,772 U.S. patients in the trial, 71 percent underwent coronary angiography before discharge from the hospital. Of these, 58 percent underwent revascularization (73 percent receiving angioplasty). The CART model for the use of angiography showed that age was the variable most predictive of angiography; only 53 percent of patients at least 73 years of age underwent angiography, as compared with 76 percent of those under 73. Among the older patients, age was again the most predictive factor; among the younger patients, the availability of angioplasty was a more important predictor (67 percent of patients in hospitals without angioplasty facilities underwent angiography, as compared with 83 percent in hospitals with such facilities). The next most important variable was recurrent ischemia, which was more predictive at hospitals without angioplasty facilities than at those with them. Both statistical models identified coronary anatomy as the most important predictor of the use and type of revascularization.

CONCLUSIONS

More patients treated with thrombolysis underwent angiography and revascularization before discharge than might be expected. Younger age and the availability of the procedures appeared to be the major determinants of the use of coronary angiography, whereas coronary anatomy largely determined the use and type of revascularization. This process appeared to select low-risk patients for intervention rather than those at higher risk, who would be the most likely to benefit.

Beta blockers prevent cardiac death following a myocardial infarction: so why are so many infarct survivors discharged without beta blockers?

Too often, infarct survivors are discharged from physician's care and/or hospital stay without beta-blocker therapy. This reflects concerns by physicians regarding precipitation of adverse effects. Ironically, many of the infarct survivors not receiving beta blockers could actually derive the greatest benefits from this treatment.

Effect of nitrates on myocardial remodeling after acute myocardial infarction

Nitrates are effective for the therapy of acute coronary syndromes, including acute myocardial infarction. Their application in acute infarction has established that vasodilators are beneficial provided hypotension is avoided. Nitrates limit early ventricular remodeling in infarction. New dosing strategies and formulations that permit chronic use after infarction with less tolerance might limit late remodeling. Over the last decade, the demonstrated effectiveness of angiotensin-converting enzyme (ACE) inhibitors in limiting ventricular dilation postinfarction has generated controversy over the usefulness of nitrates for that indication. The uncertainty has been intensified by 2 large mortality trials that tested both agents as adjuncts to conventional therapy. These trials were not designed to test whether nitrates might limit remodeling. Mechanistic experimental and clinical studies that tested whether nitrates or ACE inhibitors could effectively limit ventricular remodeling showed that both improved remodeling endpoints. However, experimental studies raise some concern about the decrease in infarct collagen associated with ACE inhibition and emphasize the fact that final outcome represents a balance of effects. That nitrates do not decrease infarct collagen could be important. Nitrate-induced early recruitment of ventricular function after late reperfusion of acute infarction might also be important. In the mortality trials, >50% of patients received open-label nitrates as per indication. Thus, the trial results to date do not suggest that nitrates are ineffective for remodeling, but rather that ACE inhibitors can confer added benefit. There has been no large clinical trial to test the efficacy of nitrates for remodeling as there has been for ACE inhibitors.

Relationship between intracoronary thrombolysis and fibrino-coagulation--special reference to TAT/PIC and FPA/PIC

To clarify the relationship between the results of intracoronary thrombolytic therapy (ICT) and fibrino-coagulation in patients with acute myocardial infarction (AMI), the thrombin-antithrombin III complex (TAT) and fibrinopeptide A (FPA), as indices of accelerated coagulation, and the plasmin- alpha 2-plasmin inhibitor complex (PIC), as an index of accelerated fibrinolysis in peripheral blood, were measured just before and after heparin injection (5,000 U), and immediately after ICT. Twenty-four patients with AMI were divided into 2 groups according to the results of ICT; successful ICT (group S) and unsuccessful ICT (group F). As a control group (group C), 14 age-matched normal volunteers were also studied. The levels of TAT and FPA before ICT were significantly higher in groups S and F than in group C (p < 0.01). The TAT level before ICT in group F was higher than that in group S (p = 0.07), however, the TAT, FPA and PIC levels showed no significant differences between groups S and F at each sampling time. TAT/PIC before ICT was significantly higher in group F than in group S (F: 0.026 +/- 0.020 vs S: 0.008 +/- 0.004, p < 0.05), whereas there was no remarkable difference in FPA/PIC between groups S and F. These results indicate that hyper-coagulation had occurred in the AMI cases and that coagulation had been more accelerated in group F. TAT/PIC might be an index of the equilibrium of the fibrino-coagulating system. Therefore, TAT/PIC measurement before thrombolytic therapy may be more useful than TAT measurement alone for evaluating recanalization in ICT.

Heparin as an adjuvant to thrombolytic therapy in acute myocardial infarction

For the treatment of acute myocardial infarction, heparin has been a topic of continuing debate for the past four decades. After review of the available data, the American College of Cardiology/American Heart Association Guidelines for the Early Management of Patients with Acute Myocardial Infarction, published in 1990, recommended intravenous heparin administration together or immediately after thrombolytic therapy to maintain the activated partial thromboplastin time approximately 1.5 to 2.0 times the control value for 24 to 72 hours. Over the past five years, with the proven benefits or thrombolytic therapy and antiplatelet therapy, investigators have been in search of the ideal thrombolytic agent as well as the best adjunctive antithrombotic strategy. We review a number of angiographic patency trials as well as the major thrombolytic mortality reduction trials in which adjunctive heparin therapy was directly assessed. These trials established the need for intravenous heparin administration with tissue plasminogen activator, but, on the other hand, do not substantiate the need for either subcutaneous or intravenous heparin use with streptokinase. New data from a large scale trial emphasizes the importance of maintaining the aPTT in the 55-70 second range to prevent bleeding complications and optimize clinical outcomes.

Synthesis and smooth muscle calcium channel antagonist effects of dialkyl 1,4-dihydro-2,6-dimethyl-4-aryl-3,5-pyridinedicarboxylates containing a nitrooxy or nitrophenyl moiety in the 3-alkyl ester substituent

A group of racemic 3-[2-nitrooxyethyl (1,3-dinitrooxy-2-propyl or 4-nitrophenylethyl)] 5-isopropyl 1,4-dihydro-2,6-dimethyl-4-[2- trifluoromethylphenyl (2-nitrophenyl or 3-nitrophenyl)]-3,5-pyridinedicarboxylates 13-15 were prepared using the Hantzsch reaction that involved the condensation of 2-nitrooxyethyl 9a, 1,3-dinitrooxy-2-propyl 9b or 4-nitrophenylethyl 9c acetoacetate with isopropyl 3-aminocrotonate 11 and 2-trifluoromethyl 12a, 2-nitro 12b or 3-nitro 12c benzaldehyde. In vitro calcium channel antagonist activities were determined using a guinea pig ileum longitudinal smooth muscle assay. Compounds 13-15 exhibited superior, or equipotent, calcium channel antagonist activity (10(-8) to 10(-10) M range) relative to the reference drug nifedipine (IC50 = 1.43 x 10(-8) M). The R1 C-3 ester substituent was a determinant of calcium channel antagonist activity where the potency order was CH2CH2ONO2 > CH2CH2-C6H4-4-NO2 > or = CH(CH2ONO2)2. In contrast, the C-4 R2-aryl substituent (2-CF3-C6H4-, 2-O2N-C6H4- or 3-O2N-C6H4-) was not a major determinant of activity. Compounds 13a-15a, which possess a 3-(2-nitrooxyethyl) ester substituent exhibit superior calcium channel antagonist smooth muscle relaxant activity (IC50 = 10(-10) M range) relative to nifedipine, could serve as potential probes to investigate the in vivo release of nitric oxide (NO) which induces vascular muscle relaxation.

Right bundle branch block of unknown age in the setting of acute anterior myocardial infarction: an attempt to define who should be paced prophylactically

It is widely accepted that patients presenting with acute anterior myocardial infarction and acute onset of right bundle branch block should be prophylactically paced in contrast with those who have a chronic bundle branch block. The admitting physician is faced with the dilemma of how to act if the age of this conduction disturbance is unknown. This problem has further intensified in recent years, with the introduction of thrombolytic treatment, where insertion of a central vascular line is associated with increased morbidity. The objectives of this study were to define clinical or electrocardiographic parameters that may help the admitting physician to decide whether patients presenting with an anterior wall myocardial infarction and a right bundle branch block of unknown age should be prophylactically paced. We examined prospectively the in-hospital clinical course of 39 consecutive patients presenting with an acute myocardial infarction in whom the age of a right bundle branch block upon admission was unknown (group C, n = 39) and compared with two similar groups of patients who presented with an acute right bundle branch block (group A, n = 38) and with a known chronic right bundle branch block (group B, n = 22). Thirty-three patients (33%) died, with cardiogenic shock being the leading cause of death in the entire population. Prophylactic pacing, which was carried out in 66% and 54% of patients in groups A and C, respectively, did not reduce mortality rates. No clinical or electrocardiographic variables on admission were predictive to support prophylactic pacing in group C. In 10 of 46 (22%) patients who were prophylactically paced with a transvenous electrode, the following complications attributed to the procedure were detected: (1) either rapid sustained ventricular tachycardia (during implantation) that was unresponsive to overdrive pacing, or ventricular fibrillation necessitating electrical defibrillation (4 patients); (2) recurrent episodes of rapid nonsustained ventricular tachycardia, which stopped only after the pacemaker was turned off (1 patient); (3) complete AV block (1 patient); (4) fever appearing on the third or fourth day after implantation (3 patients); and (4) a large hematoma in the groin in 1 patient who was treated with thrombolysis shortly before pacemaker electrode insertion. Thus, the complications of transvenous temporary pacing in the era of thrombolysis may outweight any theoretical advantage.

Successful thrombolytic therapy using tissue-type plasminogen activator in Kawasaki disease

Thrombolytic therapy using tissue-type plasminogen activator was performed in a 7-month-old boy with massive mural thrombi in large coronary aneurysms due to Kawasaki disease. Magnetic resonance imaging successfully demonstrated mural thrombi in both proximal and distal coronary aneurysms and their disappearance after thrombolytic therapy. We conclude that for preventing acute myocardial infarction and sudden death intravenous and intracoronary thrombolytic therapy with tissue-type plasminogen activator may help in infants and children with Kawasaki disease who have thrombi in coronary aneurysms.

Hirudin: initial results in acute myocardial infarction, unstable angina and angioplasty

The central role of thrombosis in the pathogenesis of acute myocardial infarction, unstable angina and complications after angioplasty has led to intense interest in developing more effective antithrombotic agents for these disorders. Hirudin, a direct thrombin inhibitor, has undergone extensive testing in experimental models and has recently been evaluated in patients in several pilot trials. Across these three indications, hirudin has been found to achieve a more consistent level of anticoagulation than heparin, as gauged by the activated parital thromboplastin time. Similarly, as an adjunct to thrombolytic therapy in acute myocardial infarction, in the treatment of unstable angina and in support of angioplasty, hirudin appeared to improve indexes of coronary reperfusion and patency. Initial results with clinical end points, including death or myocardial infarction, appeared to favor hirudin over heparin. In several large phase III trials, hirudin is being compared with heparin for all three indications. In the first phases of these trials, the rate of hemorrhagic events, including intracranial hemorrhage, was higher than expected in both the hirudin and heparin arms, which demonstrated that a safety ceiling had been reached. The reformulated Thrombolysis in Myocardial Infarction (TIMI) 9 and Second Global Use of Strategies to Open Occluded Coronary Arteries (GUSTO II) trials are using lower doses of hirudin and heparin, which should allow testing of whether the initial favorable results observed in pilot trials will translate into improved clinical outcome, with an acceptable safety profile, for patients with acute myocardial infarction or unstable angina or those undergoing angioplasty.

Adjuvants to thrombolysis after acute myocardial infarction

Preview In patients who have experienced myocardial infarction, re-occlusion of the affected vessel is disappointingly common. A variety of agents, strategies, and combination approaches have been tried as adjuncts to thrombolysis in an effort to improve left ventricular function, morbidity, and mortality in these patients. The authors summarize findings of these clinical trials, some of which are still under way.

Knowledge and practices of generalist and specialist physicians regarding drug therapy for acute myocardial infarction

BACKGROUND

The respective roles of generalist and specialist physicians in the care of patients is currently a matter of debate. Information is limited about the knowledge and practices of generalist and specialist physicians regarding conditions that both groups treat, such as myocardial infarction.

METHODS

We therefore surveyed 1211 cardiologists, internists, and family practitioners in the states of New York and Texas about four treatments demonstrated by randomized clinical trials to be associated with improved survival after myocardial infarction (thrombolytic therapy, immediate and long-term use of aspirin, and long-term use of beta-blockers) and two treatments for which such evidence is lacking (diltiazem for patients with pulmonary congestion and prophylactic lidocaine). We asked physicians about the effect of each treatment on survival and the likelihood that they would prescribe each class of drugs.

RESULTS

For the four beneficial treatments, the cardiologists believed more strongly than the internists and family physicians that survival was improved by the treatment, and they were more likely to prescribe these drugs (P < 0.001). For example, 94.1 percent of cardiologists said they were very likely to prescribe thrombolytic agents to treat an acute myocardial infarction, as compared with 82.0 percent of internists and 77.3 percent of family practitioners. Conversely, for the two treatments for which trials showed no evidence of a survival benefit, cardiologists were less likely than internists and family practitioners to think there was such a benefit and less likely to prescribe the drugs (P < 0.001). For example, 4.7 percent of cardiologists reported that they were very likely to use prophylactic lidocaine, as compared with 13.1 percent of internists, and 16.5 percent of family practitioners. When we used logistic regression to adjust for potential confounders, all the differences between the cardiologists and the internists and family practitioners remained significant (P < 0.02).

CONCLUSIONS

Internists and family practitioners are less aware of or less certain about key advances in the treatment of myocardial infarction than are cardiologists. This finding underscores the need to improve the dissemination of information from clinical trials to generalist physicians, particularly if they are to have an enlarged role in the evolving health care system.

Nitrates in myocardial infarction

Until two decades ago nitroglycerin was contraindicated in acute myocardial infarction (MI). Studies in the canine model demonstrated that low-dose intravenous (i.v.) infusion, carefully titrated to decrease mean blood pressure by 10% but not below 80 mmHg, during early stages of acute MI produced marked reduction of left ventricular (LV) preload, improvement in regional perfusion, and limitation of infarct size and remodeling. However, more i.v. nitroglycerin to decrease blood pressure further resulted in a paradoxical J-curve effect, with hypoperfusion and increased infarct size. Clinical studies have confirmed that low-dose i.v. nitroglycerin infusion for the first 48 hours after acute MI is safe, not only for improving performance in LV failure, but also for limiting ischemic injury, infarct size, remodeling, and infarct-related complications, including deaths in-hospital and up to 1 year. Recent studies suggest that more prolonged therapy with nitrates spanning the healing phase of acute anterior Q-wave MI can further limit LV remodeling and preserve function. Preliminary results of the recently completed ISIS-4 megatrial suggest, however, that long-term nitrate in patients with suspected MI in the 1990s does not improve survival significantly.

Impact of the electrocardiogram on the delivery of thrombolytic therapy for acute myocardial infarction

The initial electrocardiogram is crucial in accurately selecting patients with chest pain for thrombolytic therapy. An electrocardiogram with a large amount of ST-segment elevation and depression is "visually alarming," and therefore, may influence the efficiency of patient treatment with thrombolytic therapy. It was hypothesized that the amount of ST-segment deviation present on the initial electrocardiogram was an important variable in determining the time to initiation of thrombolysis in the emergency department. The time from arrival at the emergency department to thrombolysis was measured in 93 consecutive patients with suspected acute myocardial infarction (AMI) who were treated with intravenous thrombolytic therapy by emergency department physicians. This was correlated with the sum of ST-segment elevation and depression present on the initial electrocardiogram. AMI was proved in 83 patients (89%). In patients with proved AMI, the average time to thrombolysis was 50.8 +/- 25.6 minutes. Treatment began within the goal of < or = 30 minutes in 18 patients (22%) and was excessively delayed at > or = 60 minutes in 24 (29%). Regression analysis of multiple clinical variables revealed that ST-segment sum was the only variable that significantly influenced the time to thrombolysis (r = -0.42; p < 0.001). For patients treated in < or = 30 minutes, the average ST-segment sum was 21.1 +/- 13.5 vs 11.5 +/- 11.4 mm for those treated in > or = 60 minutes (p = 0.01). In 10 patients mistakenly treated with thrombolytic therapy, the electrocardiographic processes responsible for ST-segment elevation included the early repolarization variant, left ventricular hypertrophy, old anterior AMI with persistent ST-segment elevation, and conduction delay.(ABSTRACT TRUNCATED AT 250 WORDS)

Usefulness of transesophageal atrial pacing combined with two-dimensional echocardiography (echo-pacing) in predicting the presence and site of residual jeopardized myocardium after uncomplicated acute myocardial infarction

The usefulness of transesophageal atrial pacing combined with 2-dimensional echocardiography (echo-pacing) in predicting the presence and site of jeopardized myocardium, defined as areas of myocardium perfused by a vessel with a stenosis > or = 75% or by a collateral circulation if the supplying vessel was occluded, was evaluated in 31 patients with uncomplicated acute myocardial infarction who underwent coronary angiography. All 5 patients without jeopardized myocardium had a negative test, whereas 24 of 26 with jeopardized muscle had a positive test (sensitivity 92%; specificity 100%). To identify the site of jeopardized myocardium, tests that were positive for development of new asynergies were analyzed further, distinguishing those positive in the infarct or remote zone. Seven of 8 patients with new asynergies in the remote zone had areas of jeopardized myocardium outside the territory of distribution of the infarct-related vessel, whereas only 2 of 12 with new asynergies in the infarct zone had areas of jeopardized myocardium outside that territory (p < 0.01), correctly predicting the site of jeopardized myocardium in 17 of 20 cases. In conclusion, echo-pacing is useful for detecting the presence and site of jeopardized myocardium after an acute myocardial infarction.

Long-term function in the remote region after myocardial infarction: importance of significant coronary stenoses in the non-infarct-related artery

BACKGROUND

Left ventricular (LV) function is the most important determinant of outcome after a myocardial infarction. Global LV function after a myocardial infarction is affected not only by wall motion in the infarct zone but also by regional function in the contralateral territory. It was hypothesised that the presence of significant stenoses in coronary arteries supplying the contralateral territory might influence the ability of this region to compensate for damaged myocardium after a myocardial infarction.

METHODS AND RESULTS

79 patients treated with thrombolysis for acute myocardial infarction had coronary and ventricular angiograms within 24 h and at a mean follow up of 12 months after myocardial infarction. Wall motion in the contralateral territory was analysed and scored by the centre line method and the change over time was correlated with the presence or absence of significant (> 70%) diameter stenoses in the non-infarct-related artery. Mean (SD) contralateral territory motion worsened, from 0.74 (1.78) to -1.55 (2.06) SD chord (p < 0.001) in 40 patients with stenoses, whereas contralateral territory motion improved from -0.02 (2.4) to 0.63 (2.21) SD chord (p < 0.05) in the 39 patients without coronary stenoses. The same pattern was present whether or not the infarct artery was patent. The global left ventricular ejection fraction at 12 months was also related to contralateral territory motion (r = 0.71, p < 0.001) and to the presence of coronary stenoses (54 (15)% in those with coronary stenoses and 62 (16)% in those without, p < 0.05).

CONCLUSION

The results demonstrate that significant stenoses in arteries supplying the non-infarct territory adversely affect global and regional left ventricular function after a transmural infarction. Non-infarct artery anatomy should be considered in intervention strategies to improve left ventricular function after acute myocardial infarction.

Use of nitroglycerin for the treatment of acute myocardial infarction

After a decade of warnings against the use of nitrates in acute myocardial infarction (MI), they are becoming recognized for their potential to salvage left ventricular (LV) myocardium, geometry and function. Low-dose intravenous (IV) nitroglycerin (NTG) infusion for the first 48 h after acute MI, titrated to lower mean blood pressure by 10% to 30%, but not below 80 mmHg, has been shown to be safe, to improve hemodynamics, and to decrease infarct size, infarct expansion, complications, and deaths in a prospective, randomized, single-blind study of 310 patients. In addition, low-dose NTG infusion for the first 48 h, followed by prolonged buccal NTG given during healing after acute MI in an eccentric dose schedule to minimize tolerance, was found to limit further progressive remodeling and preserve LV function. Meta-analysis of nitrate studies in acute MI indicate that they improve survival. Preliminary and ongoing studies suggest that prolonged NTG therapy post MI can produce further benefit.