Painless MI

[SA_Medic]

Found an interesting evidence based medical study, for your perusal.

Heart Attacks Without Chest Pain More Often Fatal

Atypical Cardiac Patients Not Given Proper Drugs or Hospital Treatments

(NORTHBROOK, IL, August 9, 2004) - People who have heart attacks or other heart conditions who do not experience chest pain are commonly overlooked and undertreated at the hospital, often resulting in greater fatality rates in this group of patients. A new study in the August issue of CHEST, the peer-reviewed journal of the American College of Chest Physicians, shows that cardiac patients presenting to the hospital without chest pain have triple the death rate of other cardiac patients and are less likely to receive medications to slow the progression of a heart attack.

"While the majority of people who have acute coronary syndromes,

such as heart attacks and unstable angina, feel chest pain, some do not, but, instead, may experience atypical symptoms of fainting, shortness of breath, excessive sweating, or nausea and vomiting" said the study's lead author, David Brieger, MBBS, PhD, Concord Hospital, Sydney, Australia. "Other than excessive weating, each of the dominant symptoms of a heart attack not accompanied by chest pain independently identifies a population that is at increased risk of dying."

A group of international researchers analyzed data from the Global

Registry of Acute Coronary Events (GRACE), a registry of 20,881 patients from 14 countries, including the United States, Canada, Australia, Great Britain, and France. These patients were hospitalized with a variety of heart conditions from July 1999 to June 2002. Of the 1,763 cardiac patients who did not experience chest pain, 13 percent died in the hospital compared to 4.3 percent of those with chest pain. In addition, 23.8 percent of patients without chest pain were initially misdiagnosed when they arrived at the hospital, compared to only 2.4 percent of heart patients who experienced typical symptoms. Patients without chest pain tended to be older women and to have a history of diabetes, heart failure, or hypertension, as opposed to patients with chest pain who were more likely to be smokers with plaque buildup in their coronary arteries. Patients with atypical symptoms were also more likely to have the unfavorable outcomes of heart failure, cardiogenic shock, arrhythmias, and renal failure.

"Often, when a patient arrives at the hospital without chest pain, it is only after blood test results come back or other diagnoses are excluded that the physician reassesses the situation and determines it is an acute cardiac event after all," said Professor Brieger. "We hope that our findings will remind physicians that these events do occur in the absence of chest pain and will prompt them to make the diagnoses and institute the appropriate treatment more rapidly."

Researchers also discovered that patients who did not experience chest pain were often not given proper medication or offered appropriate cardiac medical procedures. Drugs such as aspirin and beta-blockers are usually given to patients with heart problems when they arrive at the hospital because they act as blood thinners, lesson the burden on the heart, and decrease the chances of a future coronary event; yet patients who did not have chest pain were significantly less likely to receive these drugs both during their first 24 hours of hospitalization and throughout their hospital stay. These patients were also less likely to undergo procedures such as coronary angiography and percutaneous coronary intervention and were less likely to receive statins at hospital discharge.

"The current gap in treatment and hospital outcomes for patients

with atypical symptoms is a problem that needs to be rectified," said Richard S. Irwin, MD, FCCP, President of the American College of Chest Physicians. "More emphasis needs to be given to identifying and properly treating heart attacks in patients who do not exhibit typical symptoms."

CHEST is a peer-reviewed journal published by the ACCP. It is available online each month at www.chestjournal.org.

Regards

S

[mizzoumedic74]

This is an interesting article. I would like to go out on a limb and simply state, "Treat your patients, not just symptoms". This was a quote my medic instructor used repetitively.

Meaning one simple thing: just because your patient is not presenting with crushing chest pain does not mean you should delay immediate cardiac interventions. Case in point, elderly females atypically will not present with crushing chest pain. Alzheimer's patients, same story. Diabetics or patients with a past hx of prolonged ischemia will not present with the same symptoms as a normal, prior healthy adult.

Never under treat you patients. If you suspect something, then do everything in your realm to help that patient. 12 lead EKG's are great pre-hospital diagnostic tools.

Our hospital did a recent study. It stated that over a 3 month period, those patients with an acute MI who had pre-hospital 12 leads performed vs. those that either just showed up or did not have a 12 lead done in the field, had and average door to inflation time of 31 minutes. The shortest time was 12 minutes. This was a much different story for the other unfortunates.

[supasta.]

This makes perfect sense.

I have seen a few cases of people who come into the ED AFTER having "Chest Pain" for 4-6 hours, sometimes more. They don

t come in right away because "I have chest pain, but it can't be a heart attack because my left arm doesn't hurt." or, "It has to be just reflux because it doesn't look/feel/seem like a heart attack(but Ive never had one, seen them on TV), etc." etc.....

This can also be a problem when they wait to come in, and blood test are done in the ED, and by this point the pain may have subsided or even dissapeared. Torponin Cardiac Enzyme can take up to 6 hours to show up in the blood. They may wait, and come in, have elevated troponin, and be pain free.

[kevkei]

So in a silent MI, do you propose we do cardiac bloodwork on every patient that enters an ER? Doing a 12 lead may only have evidence shown in 40% of infarcts.

It happens that when someone comes in complaining of generalized weakness for a day or two, they "just don't feel right", etc. Is it a viral illness, is it an electorlyte imbalance, is it a hypochondriac? A silent MI often is someone with no "atypical chestpain" complaints or without any infarct imposters.

I'd think the main reason the mortality rate is so high is a combination of misdiagnosis or a delayed diagnosis.

[Dustdevil]

I'd think the main reason the mortality rate is so high is a combination of misdiagnosis or a delayed diagnosis.

Agreed, Kev. They seem to be suggesting that silent MI's are somehow more pathological than symptomatic MI's, which the study doesn't seem to prove or even address.

This reminds me of the study that revealed that patients who arrived at the ER by ambulance suffered higher mortality rates than those who arrived by private conveyance. Well DUH! Those who arrive by ambulance are statistically more likely to be sicker or more seriously injured than those who arrive by conveyance! Yet everyone was quick to cite the study as if it somehow proved that medics were killing people, which was not even addressed by the study.

Can you tell that I am not too quick to trust all these "studies" that come out everyday? :roll: It seems that very few of them present a useful conclusion, and are simply presenting statistics for the sake of statistics... and for federal grant money, of course.

As Kev says, what is the solution? Do we go house to house and give everybody a 12 lead and cardiac enzyme profile just in case they are having a silent MI? Does everybody who comes into the ER with nausea get the same? Or is the statistic irrelevant to medical practice, and simply suggest the unfortunate fact of life that if you don't know you are sick, you can't seek help?

[SA_Medic]

Here is something more on it I copied and pasted from another group. Might be interresting to you.

Quote:

Patients without chest pain tended to be older women and to have a

history of diabetes, heart failure, or hypertension, as opposed to patients with chest pain who were more likely to be smokers with plaque buildup in their coronary arteries. Patients with atypical symptoms were also more likely to have the unfavorable outcomes of heart failure, cardiogenic shock, arrhythmias, and renal failure.

I was previously a paramedic liason for a hospital in a large suburban city that specialized in cardiac care.

One of the standards of education with the field medics was to get away from the term "chest pain" (which was the title of the treatment protocol), as we found the above to be true about femals and no pain. The point being, you can ask one of the females in the above catagory if she has any chest pain, and they will say no as she decompensates in front of you. The line of questions we zeroed in on was a "new ill feeling" or "new feeling of uneasiness". In our experience with females coming through the door and going to the cath lab, these two questions seemed to catch the females listed above.

After presenting this info several times, we saw a significant increase in correctly treating the female portion of the MI group pre-hospital, instead of receiving the "ill female" via ambulance with no real treatment.

Thanks

Jerry

Jerry Miller

Medical Base Supervisor

Mercy Air Base 8

/Quote

Regards

S

[Dustdevil]

Ahhh! Now there is some information that actually offers something useful!

I always applaud efforts to identify and serve those patients who typically get overlooked by the system. Especially when it takes nothing more than a little outside-the-box thinking to do so.

Thanks for the update, SA!

[Ace844]

(Published Online First: 9 December 2005. doi:10.1136/hrt.2005.071423

Heart 2006;92:916-920

© 2006 by BMJ Publishing Group Ltd & British Cardiovascular Society

CARDIOVASCULAR MEDICINE

B-type natriuretic peptide can detect silent myocardial ischaemia in asymptomatic type 2 diabetes

B S Rana1 @ J I Davies1, M M Band1, S D Pringle2, A Morris1 and A D Struthers1

1 Division of Medicine and Therapeutics, University of Dundee, Ninewells Hospital and Medical School, Dundee, UK

2 Department of Cardiology, Ninewells Hospital and Medical School, Dundee, UK

Correspondence to:

Dr Justine Davies

Department of Clinical Pharmacology, Ninewells Hospital and Medical School, Dundee DD1 9SY, UK; j.i.davies@dundee.ac.uk)

Objective: To find out whether B-type natriuretic peptide (BNP) detects silent myocardial ischaemia in patients with type 2 diabetes, since many of these patients have silent ischaemia leading to unexpected cardiac deaths.

Design: Prospective cross-sectional study with consecutive recruitment of patients.

Setting: Outpatient, single centre.

Patients: 219 patients with type 2 diabetes. Patients were excluded if they had a history or evidence of cardiac failure.

Outcome measures: BNP, echocardiography and exercise tolerance test (ETT). BNP was compared with the ETT result in all patients and specifically in those who had no apparent ischaemic heart disease (IHD).

Results: 121 patients had no history of IHD or cardiac failure and of these patients 85 had a clearly abnormal or normal ETT result. BNP was higher in patients with an abnormal than with a normal ETT (mean 58.2 (SD 46.3) v 24.4 (SD 15.7) pg/ml, p < 0.001). In univariate analysis BNP was an independent predictor of an abnormal ETT (p < 0.001). In multivariate analysis BNP remained an independent predictor of the ETT result. BNP concentration over 20 pg/ml predicted an abnormal ETT result with a sensitivity of 87% and specificity of 37%, and BNP over 40 pg/ml had a sensitivity of 63% and a specificity of 81%.

Conclusion: BNP is of value in predicting silent ischaemia on exercise testing in asymptomatic patients with type 2 diabetes.

[Ace844]

(The American Journal of Emergency Medicine

Volume 24 @ Issue 4 , July 2006, Pages 435-439

doi:10.1016/j.ajem.2005.12.017

Copyright © 2006 Elsevier Inc. All rights reserved.

Original Contribution

β-Blocker use in elderly ED patients with acute myocardial infarction

Presented at the New York Regional SAEM, New York City, NY, March 31, 2004 as a moderated poster presentation (awarded “Best Moderated Poster”); the Scientific Assembly of the Pennsylvania Chapter, American College of Emergency Physicians, April 21, 2004, Philadelphia, Pa, as a poster presentation (awarded “Best Poster Presentation”); the National Society for Academic Emergency Medicine Scientific Assembly, May 16-19, 2004, Orlando, Fla, as a poster presentation.

David D. Vega MD, a, , Kendra L. Dolan MDa and Marc L. Pollack MD, PhDa

aDepartment of Emergency Medicine, York Hospital, York, PA 17405, USA

Received 6 October 2005; accepted 21 December 2005. Available online 17 June 2006.)

Original Contribution

β-Blocker use in elderly ED patients with acute myocardial infarction

Presented at the New York Regional SAEM, New York City, NY, March 31, 2004 as a moderated poster presentation (awarded “Best Moderated Poster”); the Scientific Assembly of the Pennsylvania Chapter, American College of Emergency Physicians, April 21, 2004, Philadelphia, Pa, as a poster presentation (awarded “Best Poster Presentation”); the National Society for Academic Emergency Medicine Scientific Assembly, May 16-19, 2004, Orlando, Fla, as a poster presentation.

David D. Vega MD, a, , Kendra L. Dolan MDa and Marc L. Pollack MD, PhDa

aDepartment of Emergency Medicine, York Hospital, York, PA 17405, USA

Received 6 October 2005; accepted 21 December 2005. Available online 17 June 2006.

Abstract

Background

Despite the effectiveness of early β-blocker (BB) use in reducing mortality in acute myocardial infarction (AMI), they remain underutilized in the emergency department (ED) management of AMI. The elderly, with higher AMI mortality, and women, may be particularly vulnerable to underutilization of BB.

Objective

To determine the effect of age and gender on BB use in AMI in the ED.

Methods

A retrospective study of all ST-elevation AMI (STEMI) ED patients presenting to a community hospital ED from 2001 to 2003. Any contraindication to BB use (hypotension, bradycardia, AV block, active bronchospasm, and active congestive heart failure) was determined. Chi-square analysis was used to determine differences by gender and age.

Results

Three hundred eighty-five patients with STEMI were identified. Thirty-eight percent were women and 71% were over 60 years of age. Of the 270 (70%) who did not receive BB, 141 (52%) had contraindications to BB use. The total BB eligible group was 244 (63%). Of patients without contraindications to BB, 53% did not receive BB in the ED. By gender, 83 (54%) males and 46 (51%) females did not receive BB (P= .669). By age, 96 subjects (59%) over age 60 and 33 subjects (41%) under age 60 did not receive BB (P= .011).

Conclusion

Despite convincing evidence of effectiveness, BB remain underutilized in ED management of AMI, especially in the elderly. There does not appear to be a gender difference in BB use. Education programs should be directed towards emergency physicians regarding BB use in AMI, especially in elderly ED patients.

Article Outline

1. Introduction

2. Methods

2.1. Study design

2.2. Study population and setting

2.3. Measurements

2.4. Data analysis

3. Results

4. Discussion

5. Limitations and future questions

6. Conclusions

References

1. Introduction

The American Heart Association (AHA)/American College of Cardiology lists β-blockers (BBs) as a class I recommendation for the treatment of acute myocardial infarction (AMI) in patients without contraindications [1]. As early as 1971, BBs were recognized to reduce infarct size in experimental animals [2]. The use of BB in the setting of AMI has repeatedly been shown to significantly reduce morbidity and mortality [3], [4] and [5]. β-Blockers lower heart rate, decrease myocardial contractility, and decrease peripheral vascular resistance, thereby reducing oxygen demand and workload. They also reduce infarct size and decrease the risk of wall rupture [6] and [7]. β-Blockers also help to prevent dysrhythmias including ventricular tachycardia and ventricular fibrillation [8], [9] and [10].

Despite their effectiveness, BBs remain underused in AMI [11] and [12]. The AHA/American College of Cardiology recommends BB within 12 hours of infarction [1]; however, there is strong evidence that earlier administration of BB, that is, in the ED, is associated with decreased morbidity and mortality [13], [14] and [15]. β-Blocker use in the setting of AMI has been shown to have the greatest decrease in mortality if given within 2 hours of symptom onset [14]. Nonetheless, many patients without contraindications with AMI are not given BB in the ED [11] and [16]. A small ED study and others indicate that females and elderly patients may not receive BB as frequently as males and younger patients, respectively [16], [17], [18] and [19]. The objective of our study was to determine the frequency that BB are given in the ED to patients with ST-elevation AMI (STEMI) and to determine if there is a significant difference in the treatment of females and the elderly.

2. Methods

2.1. Study design

This is a retrospective study of all patients with STEMI in the ED from December 2001 through October 2003. Patients were identified by admission diagnosis of AMI and were included if they had both STEMI (at least 1 mm in 2 contiguous limb leads or 2 mm in 2 precordial leads) on electrocardiographic review and positive cardiac markers (troponin I or creatine kinase–MB) on chart review. Once subjects were identified, BB (metoprolol) use in the ED was determined via review of Pyxis (a hospital medication administration system) data on medication use in the ED. For those subjects that were not given BB, the presence of any contraindications to BB use (hypotension, bradycardia, AV block, active bronchospasm, and active congestive heart failure [CHF]) were identified. Institutional review board approval was obtained, and HIPAA regulations were followed.

2.2. Study population and setting

The study was performed in the ED of a 63 000 visits per year community teaching hospital. Patients with AMI in the York Hospital catchment area are not diverted by emergency medical services to other institutions because York Hospital is capable of performing all invasive cardiac procedures including angiography, stent placement, and coronary artery bypass graph surgery. We identified patients with STEMI through a retrospective chart review. Patients were considered to have a contraindication to BB use if they had hypotension (systolic blood pressure <100), bradycardia (heart rate <60), second- or third-degree heart block, acute asthma, or chronic obstructive pulmonary disease (COPD) exacerbation, or acute CHF (Table 1). A history of asthma, COPD, or CHF alone was not considered a contraindication to BB use.

Table 1.

Contraindications to BB use Systolic blood pressure <100 mm Hg

Heart rate <60 beats per minute

Second- or third-degree atrioventricular block

Acute exacerbation of asthma or COPD

Acute CHF

2.3. Measurements

Standardized data collection sheets were used. All personnel collecting data were familiar with inclusion and exclusion criteria and had the definitions of contraindications to BB use available as outlined on the data collection sheets.

2.4. Data analysis

χ2 Analysis was performed on the data.

3. Results

A total of 1395 charts of adult patients with an admitting diagnosis of AMI from 2001 through 2003 were reviewed. Of these 1395 patients, 402 had positive cardiac markers and ST-segment elevation on the initial electrocardiograph consistent with our inclusion criteria. Sixteen patients were excluded from final analysis secondary to incomplete Pyxis data, leaving 385 patients. These patients included 238 (63%) males and 147 (38%) females. Of all patients, 112 (29%) were younger than 60 years and 273 (71%) were 60 years or older. Table 2 presents the demographics of the 385 patients included in this study.

Table 2.

Patient characteristics Characteristic

Total no. of patients N = 385

Age mean ± SD (range), y 68 ± 14 (33-99)

<60 112 (29%)

≥60 273 (71%)

Sex

Female 147 (38%)

Male 238 (62%)

Of the 385 patients, as illustrated in Fig. 1, 141 (37%) had contraindications to BB as identified via chart review, leaving 244 (63%) patients eligible to receive BB in the ED. The exact nature of the BB contraindication in the 141 patients is listed in Table 3. Of those eligible for BB, there were 153 (63%) males, 91 (37%) females, 81 (33%) younger than 60 years, and 163 (67%) older than 60 years.

(58K)

Fig. 1. Enrollment procedure of patients with STEMI.

Table 3.

Nature of contraindications to BB use (n = 141) n %

Bradycardia 77 54.6

Hypotension 53 37.6

Acute CHF 49 34.8

Third-degree AV block 7 5

Second-degree AV block 3 2.1

Acute COPD 3 2.1

Acute Asthma 0 0

Ninety-four (66.7%) had single contraindication and 47 (33.3%) had multiple contraindications.

Of the 244 patients with STEMI who were eligible to receive BB, 129 (53%) did not receive BB while in the ED. By sex, 83 (54%) of 153 males vs 46 (51%) of 91 females were not treated with BB (P = .669). By age, 59% (n = 96) of patients 60 years and older did not receive BB, whereas 41% (n = 33) of patients younger than 60 years did not receive BB (P = .011).

4. Discussion

β-Blockers are an integral part of the treatment of AMI and have been listed as a class I recommendation for the treatment of AMI by the AHA [1]. β-Blockers reduce morbidity and mortality by lowering heart rate and decreasing oxygen demand and myocardial workload, which all help to reduce infarct size and decrease the risk of wall rupture and prevent dysrhythmias including ventricular tachycardia and ventricular fibrillation [2], [3], [4], [5], [6], [7], [8], [9], [10] and [20]. The AHA recommends the use of BB within 12 hours of symptoms [1]. However, other studies have shown BB have their greatest effect if used within 2 hours of symptom onset [14] and [15]. Therefore, for optimal patient outcomes, the emergency physician is responsible for the decision to administer BB to patients with AMI. Despite these data, BBs are still underused in AMI; in fact, some small studies showed that females and the elderly may be undertreated in comparison to males and younger patients, respectively [11], [12], [16], [17], [18] and [19].

Recent data show only 28% of patients with AMI received BB in the ED at a university-affiliated teaching hospital vs 48.6% who received BB within 24 hours of AMI in a multicenter study across the United States [16] and [17]. In our study of a large community teaching ED (Fig. 1), 47% of eligible patients with STEMI received BB while in the ED, which further adds validity to studies showing that BB use is underused in the ED. Likewise, our data show that the elderly without BB contraindications also receive treatment far less than their younger counterparts, that is, 59% of those older than 60 years vs 41% of those younger than 60 years did not receive BB (P = .011). This supports data from a multicenter trial that showed 51% of the elderly without contraindications did not receive BB [17]. However, our data did not support the previous finding that females with AMI receive BB less frequently than males [16]. A larger study is needed to further clarify sex differences in BB administration.

We have demonstrated that BBs continue to be underused in the ED overall and particularly in the elderly. Our next goal is to identify the underlying reasons for suboptimal BB administration in the ED. A previous retrospective chart review at a community hospital supported several reasons—ED physicians wanting to defer to cardiologists, cardiologists who overestimate the amount of time they are giving BB, and ED physicians who do not know the current contraindications to BB use [11]. Based on informal discussions with EP, we hypothesize that BBs are underused in the ED for several reasons: clinicians unfamiliar with evidence showing benefit of early BB use, clinicians unclear of exact contraindications to BB use (particularly regarding nonacute asthma, COPD, and CHF), concern for more frequent adverse outcomes in the elderly, and time constraints in the ED [21]. Further studies are needed to identify and rectify the causes so that patient care can be improved. We plan to institute educational measures to improve quality and standardized AMI order sheets and reevaluate BB use in the ED.

5. Limitations and future questions

The study method of retrospective chart review has inherent flaws. The data may be skewed by inadequate documentation of contraindications to BB use by clinicians, which would not be detected on chart review.

The data extracted from the Pyxis pertained to the use of BB. When medicine is withdrawn from the Pyxis, it is recorded electronically and we assume that this medicine was then given to the patient unless the electronic record indicates that the medicine was returned to the Pyxis. However, we did not have adequate documentation of medicines that were discarded by the nursing staff, and it is plausible that some medicines were withdrawn and not administered. This would have resulted in an even larger nonutilization of BB. Nonetheless, given the nature of the study, it is felt that the errors of incomplete documentation and Pyxis data accuracy are minimal and unavoidable.

External validity could be questioned, as this was a single-center study in a community teaching hospital. However, our data are supported by other studies that have found underuse of BB in the ED [11], [16] and [17].

6. Conclusions

Our study shows that BBs are underused for STEMI in the ED. Although there was no significant difference in BB use by sex, elderly patients were significantly less likely to receive BB than younger patients in the ED. We postulate that there are many factors contributing to poor compliance: clinicians unfamiliar with evidence showing benefit of early BB use, clinicians unclear of exact contraindications to BB use (particularly regarding nonacute asthma, COPD, and CHF), concern for more frequent adverse outcomes in the elderly, and time constraints in the ED. Certainly, if patients are moved rapidly from the ED to either the catheterization laboratory or the cardiac care unit, BB can be administered in other settings than the ED. A formal survey of ED providers may prove useful in determining reasons why EM physicians are not using BB as often as they should. We plan to develop educational programs for ED clinicians aimed at increasing the use of BB in STEMI. In addition, a recent study has demonstrated that standing orders increase compliance with BB use in AMI [22].

References

[1] T.J. Ryan, E.M. Antman, N.H. Brooks, R.M. Califf, L.D. Hillis and L.F. Hiratzka et al., ACC/AHA 1999 guidelines for the management of patients with acute myocardial infarction: executive summary and recommendations: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Management of Acute Myocardial Infarction), Circulation 100 (1999), pp. 1016–1030. Abstract-EMBASE | Abstract-Elsevier BIOBASE | Abstract-MEDLINE

[2] P.R. Maroko, J.K. Kjekshus and B.E. Sobel et al., Factors influencing infarct size following experimental coronary artery occlusions, Circulation 43 (1971), pp. 67–82. Abstract-MEDLINE

[3] β-Blocker Heart Attack Trial Research Group, A randomized trial of propanolol in patients with acute myocardial infarction. I. Mortality results, JAMA 247 (1982), pp. 1707–1714.

[4] The MIAMI Trial Research Group, Metoprolol in acute myocardial infarction (MIAMI). A randomized placebo-controlled international trial, Eur Heart J 6 (1985), pp. 199–226.

[5] First International Study of Infarct Survival Collaborative Group, Randomized trial of intravenous atenolol among 16 027 cases of suspected acute myocardial infarction: ISIS-1, Lancet 2 (1986), pp. 57–66.

[6] S. Yusuf, R. Peto, J. Lewis, R. Collins and P. Sleight, Beta blockade during and after myocardial infarction: an overview of the randomized trials, Prog Cardiovasc Dis 27 (1985), pp. 335–371. Abstract-MEDLINE | Abstract-EMBASE

[7] J. Galcera-Tomas, F.J. Castillo-Soria and M.M. Villegas-Garcia et al., Effects of early use of atenolol or captopril on infarct size and ventricular volume: a double-blind comparison in patients with anterior acute myocardial infarction, Circulation 103 (2001) (6), pp. 813–819. Abstract-MEDLINE

[8] L. Ryden, R. Ariniego and K. Arnman et al., A double-blind trial of metoprolol in acute myocardial infarction. Effects on ventricular tachyarrhythmias, N Engl J Med 308 (1983), pp. 614–618. Abstract-EMBASE | Abstract-MEDLINE

[9] S. Ahnve, L. Erhardt and T. Lundman et al., Effect of metoprolol on QTc intervals after acute myocardial infarction, Acta Med Scand 208 (1980) (3), pp. 223–228. Abstract-MEDLINE | Abstract-EMBASE

[10] H. Evrengul, D. Dursunoglu and M. Kayikcioglu et al., Effects of a beta-blocker on ventricular late potentials in patients with acute anterior myocardial infarction receiving successful thrombolytic therapy, Jpn Heart J 45 (2004) (1), pp. 11–21. Abstract-MEDLINE | Full Text via CrossRef

[11] M.M. O'Bryan and J.S. Banas, Intravenous beta-blockers in acute myocardial infarction: perceived versus actual use by cardiologists and emergency physicians, Am J Emerg Med 16 (1998), pp. 623–626. SummaryPlus | Full Text + Links | PDF (437 K)

[12] W.J. French, Trends in acute myocardial infarction management. Use of the national registry of myocardial infarction in quality improvement, Am J Cardiol 85 (2000), pp. 5B–9B.

[13] R.M. Gunnar, P.D.V. Bourdillon and D.W. Dixon et al., 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), J Am Coll Cardiol 16 (1990), pp. 249–252.

[14] The TIMI Study Group, Comparison of invasive and conservative strategies after treatment with intravenous tissue plasminogen activator in acute myocardial infarction: results of the thrombolysis in myocardial infarction (TIMI) phase II trial, N Engl J Med 320 (1989), pp. 618–627.

[15] S. Yusuf, Early intravenous beta blockade in acute myocardial infarction, Postgrad Med Spec No (1988), pp. 90–95. Abstract-MEDLINE

[16] D. Pancu and D.C. Lee, Beta-blocker use in the emergency department in patients with acute myocardial infarction undergoing primary angioplasty, J Emerg Med 24 (2003), pp. 379–382. SummaryPlus | Full Text + Links | PDF (66 K)

[17] H.M. Krumholz et al., Early β-blocker therapy for acute myocardial infarction in elderly patients, Ann Intern Med 131 (1999), pp. 648–654. Abstract-MEDLINE | Abstract-EMBASE

[18] T.J. McLaughlin, S.B. Soumerai and D.J. Willison et al., Adherence to national guidelines for drug treatment of suspected acute myocardial infarction: evidence for under treatment in women and the elderly, Arch Intern Med 156 (1996) (7), pp. 799–805. Abstract-EMBASE | Abstract-MEDLINE

[19] J.H. Gerwitz, R.J. Goldberg and Z. Chen et al., Beta-blocker therapy in acute myocardial infarction: evidence for underutilization in the elderly, Am J Med 93 (1992) (6), pp. 605–610.

[20] K.E. Ellison and G. Gandhi, Optimising the use of beta-adrenoceptor antagonist in coronary artery disease, Drugs 65 (2005) (6), pp. 787–797. Abstract-MEDLINE | Abstract-EMBASE | Abstract-Elsevier BIOBASE | Full Text via CrossRef

[21] J. Chen, M.J. Radford and Y. Wang et al., Effectiveness of beta-blocker therapy after acute myocardial infarction in elderly patients with chronic obstructive pulmonary disease or asthma, J Am Coll Cardiol 37 (2001) (7), pp. 1950–1956. SummaryPlus | Full Text + Links | PDF (183 K)

[22] E.H. Bradley, J. Herrin, J.A. Mattera and E.S. Holmboe et al., Quality improvement efforts and hospital performance rates of beta-blocker prescription after acute myocardial infarction, Med Care 43 (2005) (3), pp. 282–292. Abstract-MEDLINE | Full Text via CrossRef