HOME SUBSCRIPTIONS CURRENT ISSUE PAST ISSUES CARDIOSOURCE SEARCH HELP FEEDBACK		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Figures Only Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Zahn, R. Search for Related Content PubMed PubMed Citation Articles by Zahn, R.

CLINICAL STUDIES

Acute myocardial infarction occurring in versus out of the hospital: patient characteristics and clinical outcome

Ralf Zahn, MD^*, Rudolf Schiele, MD^a, Karlheinz Seidl, MD^a, Thomas Kapp, MD^*, Hans Georg Glunz, MD, Edwin Jagodzinski, MD, Thomas Voigtländer, MD, Martin Gottwik, MD^||, Gunther Berg, MD^¶, Helmut Thomas, MD^#, Jochen Senges, MD^a for the Maximal Individual TheRapy in Acute Myocardial Infarction (MITRA) Study Group

^a Herzzentrum Ludwigshafen, Bad Dürkheim, Germany
^* Vincentius Krankenhaus Speyer, Bad Dürkheim, Germany
Westpfalz-Klinikum Kaiserslautern, Bad Dürkheim, Germany
Marienkrankenhaus Ludwigshafen, Bad Dürkheim, Germany
Johannes Gutenberg Universität Mainz, Bad Dürkheim, Germany
^|| Klinikum Nürnberg, Bad Dürkheim, Germany
^¶ Universitätsklinikum Homburg/Saar, Bad Dürkheim, Germany
^# Evangelisches Krankenhaus, Bad Dürkheim, Germany

Manuscript received October 8, 1999; revised manuscript received December 16, 1999, accepted February 9, 2000.

Reprint requests and correspondence: Dr. Ralf Zahn, Herzzentrum Ludwigshafen, Department of Cardiology, Bremserstrasse 79, D-67063 Ludwigshafen, Germany
erzahn{at}aol.com

	Abstract

Top Abstract Methods Results Discussion References

 
OBJECTIVES

We describe the baseline characteristics and clinical course of patients who had an acute myocardial infarction (AMI) during their hospital stay.

BACKGROUND

In comparison with patients who had an AMI outside of the hospital (prehospital AMI), the data on patients who had an AMI in the hospital are poorly described.

METHODS

Patients with an in-hospital AMI were prospectively registered in the Southwest German Maximal Individual TheRapy in Acute myocardial infarction (MITRA) study and compared with patients with prehospital AMI.

RESULTS

Of 5,888 patients with AMI, 403 patients (6.8%) had an in-hospital AMI. These patients were older, more often male and sicker as compared with the patients with a prehospital AMI. They also showed a higher prevalence of concomitant diseases, such as arterial hypertension, diabetes mellitus, renal insufficiency and contraindications for thrombolysis. There was no significant difference regarding the use of reperfusion therapy, either thrombolysis (in-hospital AMI 44.2% vs. prehospital AMI 49.1%; odds ratio [OR] 0.86, 95% confidence interval [CI] 0.70 to 1.05) or primary angioplasty (9.9% vs. 8.2%; OR 1.23, 95% CI 0.88 to 1.73), or a combination of both, between the two groups. The interval from symptom onset to the start of treatment in patients receiving reperfusion therapy was 55 min for patients with an in-hospital AMI versus 180 min for patients with a prehospital AMI (p = 0.001). In-hospital death occurred in 110 (27.3%) of 403 patients with an in-hospital versus 762 (13.9%) of 5,485 patients with a prehospital AMI (OR 2.33, 95% CI 1.85 to 2.94). This was confirmed by logistic regression analysis after adjusting for other confounding variables (OR 1.67, 95% CI 1.23 to 2.24).

CONCLUSIONS

In-hospital AMI occurred in 6.8% of patients. Time to intervention was shorter; however, the use of reperfusion therapy for in-hospital AMI was not different from that for prehospital AMI. In particular, primary angioplasty seems to be underused in these patients. This, as well as the selection of patients, may result in the high hospital mortality rate of 27.3%.

Abbreviations and Acronyms   AMI = acute myocardial infarction   CI = confidence interval   ECG = electrocardiogram   MITRA = Maximal Individual TheRapy in Acute myocardial infarction study   MONICA = Multinational MONitoring of Trends and Determinants in CArdiovascular Disease   OR = odds ratio

A search in Medline from 1980 to 1999 resulted in only two reports on in-hospital infarctions (9,10). The study by Zmyslinski et al. (9) was published before the era of reperfusion therapy, and the study by L’Abbate et al. (10) focused on preinfarction features. Each report provided data on only 50 patients with in-hospital Q wave AMI. Therefore, we used the data of the Southwest German Maximal Individual TheRapy in Acute myocardial infarction (MITRA) study (11) to analyze the proportion and clinical course of patients with in-hospital versus prehospital AMI.

	Methods

Top Abstract Methods Results Discussion References

 
The MITRA study was a prospective, multicenter, observational study of the current treatment of AMI in Germany (11). Fifty-four hospitals in Southwest Germany participated in the study, including university hospitals, tertiary-care centers and smaller hospitals. All patients presenting within the first 96 h of the onset of pain were registered prospectively, as soon as the diagnosis of AMI had been made. Recruitment of patients started in June 1994 and ended in January 1997.

Acute myocardial infarction was diagnosed on the basis of the two following criteria: 1) persistent angina pectoris for 20 min 2) ST segment elevation of 1 mm in at least two standard leads or 2 mm in at least two contiguous precordial leads; or the presence of left bundle branch block. It was later confirmed by the elevation of cardiac enzymes of more than twice the normal upper range.

Definitions.   Postinfarction angina was diagnosed in the presence of new angina pectoris within two weeks after myocardial infarction. Reinfarction was defined as recurrent chest pain lasting >20 min with either new ST segment elevation, emergency angiographic confirmation of a reoccluded vessel or recurrent elevation of cardiac enzymes. Minor stroke was defined as a transient cerebral ischemia; major stroke as a persistent cerebral ischemia. A combined clinical end point was defined by the occurrence of death, reinfarction or stroke. Patients were prospectively classified as being eligible for thrombolysis after exclusion of patients with either a nondiagnostic first electrocardiogram (ECG) or contraindications for thrombolysis (e.g., recent surgery or trauma <14 days, recent cerebral infarction <3 months or active bleeding).

For this analysis, patients who had an AMI during their hospital stay (in-hospital infarction) were compared with patients who had an AMI outside of the hospital and showed a prehospital delay of 12 h (prehospital infarction). Patients who had an AMI during or within 24 h after coronary angiography, percutaneous transluminal coronary angioplasty or stent implantation were regarded as having in-hospital infarctions. Patients initially registered as having a prehospital infarction and who subsequently had an in-hospital reinfarction were not included as the in-hospital infarction group. Admission diagnosis was not evaluated, according to the study protocol, in patients with an in-hospital AMI. Of the 54 participating hospitals, four performed a chart review to define the admission diagnosis. Admission diagnosis was available in 88 (21.8%) of 403 patients with an in-hospital AMI.

Statistics.   Data collection
Data on the prehospital period and the early in-hospital period (first 48 h) were collected within the first two to three days in the intensive care unit. Clinical events occurring thereafter were registered on a separate record form on hospital discharge. Each participating center had committed, by written consent, to include each patient with an AMI during the study period. The patients gave written, informed consent for processing their anonymous data. All data sheets were sent to the central data processing center (Department of Cardiology, Heart Center Ludwigshafen) for uniform monitoring and registration.

Data analysis
Absolute numbers and percentages were computed to describe the patient group. Median values and 25% and 75% percentiles were computed. Categoric values were compared by chi-square analysis or the Cochran-Mantel-Haenszel test, and the odds ratio (OR) and 95% confidence interval (CI) were computed. Continuous variables were compared by the two-tailed Wilcoxon rank-sum test. Multiple logistic regression was used to analyze factors influencing hospital mortality and the combined end point. The variables examined included age, gender, location of infarction, previous infarction, presence of heart failure on hospital admission, systolic blood pressure, heart rate, bundle branch block, concomitant diseases, concomitant medications, thrombolytic eligibility and the occurrence of an infarction in or out of the hospital. P values <0.05 were considered significant. All p values are two-tailed. The tests were performed using the SAS statistical package, version 6.12 (Cary, North Carolina).

	Results

Top Abstract Methods Results Discussion References

 
Selection of patients from the MITRA trial is shown in Figure 1. Of 5,888 patients with AMI, 403 (6.8%) had an in-hospital AMI and 5,485 (93.2%) had a prehospital AMI. The baseline characteristics of the patients are shown in Table 1. Patients who had an in-hospital AMI were older, more often male and sicker as compared with patients with a pre-hospital AMI. The first ECG was less often diagnostic in patients with an in-hospital AMI (64.2% vs. 72.6%; OR 0.68, 95% CI 0.55 to 0.84). These patients also showed a higher prevalence of concomitant diseases, such as arterial hypertension, diabetes mellitus and renal insufficiency. In addition, they more often had contraindications for thrombolysis, such as a history of ulceration, active bleeding, a recent cerebral infarction or a recent trauma or surgery.

View larger version (23K): [in this window] [in a new window]   Figure 1 Selection of patients from the MITRA trial.

View larger version (22K): [in this window] [in a new window]   Figure 2 Admission diagnosis in 88/403 (21.8%) of patients with in-hospital myocardial infarction.

	Discussion

Top Abstract Methods Results Discussion References

 
Acute myocardial infarction occurring in patients who have already been admitted to the hospital (in-hospital infarction) is an entity that is poorly described in medical data. A search in Medline from 1980 to 1999 revealed only two articles dealing with this subject (9,10). Both were retrospective and described the results of 50 patients with an in-hospital AMI. However, this subgroup of patients might be of important clinical interest, because they give us the chance to know what could be achieved with current therapy in patients with AMI, if all patients with AMI reached the hospital alive.

Prevalence and characteristics of patients with an in-hospital AMI.   The prevalence of in-hospital infarction was 6.8% (403 of 5,888) of the patients with AMI in the prospective MITRA trial. In-hospital infarctions occurred with a median delay of 2.5 days after admission to the hospital. Zmyslinski et al. (9) reported a 9.8% rate (50 of 510) of patients with in-hospital infarctions, and L’Abbate et al. (10) reported a 2% to 3% incidence for patients with in-hospital Q wave in-hospital AMI. The low incidence reported by L’Abbate et al. (10) is likely attributed to the population for which it was given. This 2% to 3% incidence for Q wave in-hospital AMIs has been reported for patients with documented ischemia at rest during the same hospital period. In our study, patients with in-hospital infarctions were older and sicker as compared with patients with prehospital infarctions. They also more often had a history of diabetes mellitus and arterial hypertension, as well as a higher prevalence of renal insufficiency and contraindications for thrombolysis. These findings are in concordance with the patient description made by Zmyslinski et al. (9).

Admission diagnosis.   Evaluation of the admission diagnosis in patients with an in-hospital AMI was not part of the initial protocol of the MITRA registry. To get an impression of the categories of patients with in-hospital infarctions, four hospitals agreed to perform a chart review of their patients with an in-hospital AMI to look for the admission diagnosis. As expected, the majority of patients with an in-hospital AMI were admitted to the hospital with stable or unstable angina pectoris (72.8%). Only a minority of patients with an in-hospital AMI had their infarction after operation (8%).

Clinical course.   The hospital mortality rate was 27.3% (110 of 403) for patients with an in-hospital AMI versus 13.9% (762 of 5,485) for patients with a prehospital AMI (OR 2.33, 95% CI 1.85 to 2.94). This difference remained significant after performing a logistic regression analysis adjusting for other confounding variables (OR 1.54, 95% CI 1.28 to 1.86). The same was shown for the combined end point of death, reinfarction or stroke. This death rate of 27.3% is close to the 29% death rate reported by L’Abbate et al. in 1986 (10), but is much lower than the 66% death rate reported by Zmyslinski et al. in 1981 (9). Although the number of patients in both studies was small, the difference between the 1981 data and the 1986 data may reflect better treatment (reperfusion therapy and adjunctive therapy) in these patients.

Patients with an in-hospital AMI were less often treated with beta-blockers (44% vs. 53.7%; OR 0.68, 95% CI 0.56 to 0.84), as well as with heparin, nitroglycerin and aspirin. This may be mainly explained by different patient characteristics. However, the proportion of patients receiving no reperfusion therapy (primary angioplasty, thrombolysis or a combination of thrombolysis and angioplasty) was not different between the two groups (in-hospital AMI 43.4% vs. prehospital AMI 41.7%; OR 1.07, 95% CI 0.88 to 1.32). Patients with an in-hospital AMI more often had contraindications for thrombolysis. Therefore, the proportion of patients regarded as thrombolytic eligible was significantly lower in the in-hospital AMI group (59.3% vs. 74.3%; OR 0.51, 95% CI 0.41 to 0.62). However, even in patients eligible for thrombolysis, 30% were not treated with reperfusion therapy, with no difference between prehospital and in-hospital infarctions. This rate is close to the 24% rate in thrombolytic-eligible patients reported in the National Registry of Myocardial Infarction-2 study (12), which also did not use reperfusion therapy. Barron et al. (12), as well as Wagner et al., on behalf of the Myocardial Infarction Registry Investigators (13), found that age >70 years, female gender, presence of left bundle branch block, prehospital delays >6 h and various preexisting cardiovascular conditions were independent predictors that even thrombolytic-eligible patients would not receive reperfusion therapy. In patients with contraindications for thrombolysis, primary angioplasty should be the ideal reperfusion therapy (14–18). Our data show that primary angioplasty seems not to be used properly in this subgroup of patients with AMI, and hospitals without the facilities to perform primary angioplasty should transfer such patients, which is safe and effective (19–23).

The interval from the onset of symptoms to the start of the treatment in patients treated with reperfusion therapy was 55 min (median) for patients with an in-hospital AMI versus 180 min (median) for patients with a prehospital AMI (p = 0.001). This shows that patients with an in-hospital AMI are quickly recognized, and time to reperfusion therapy is quite short.

Hospitals with and without angioplasty facilities.   At hospitals with the facilities to perform angioplasty, there was a higher proportion of patients with in-hospital infarctions of all patients with AMI, as compared with hospitals without such facilities (7.9% [136 of 1,717] vs. 6.4% [267 of 4,171]) (OR 1.26, 95% CI 1.02 to 1.56). This could result from a combination of selection of patients, because many patients with unstable or stable coronary syndromes will be sent to hospitals with the facilities to perform angioplasty, and the possible consequences of such interventions, such as AMI due to dissections or stent thrombosis after coronary balloon angioplasty. However, the proportion of patients with an in-hospital AMI not treated with reperfusion therapy was slightly but not significantly lower at hospitals with angioplasty facilities (38.2%) as compared with hospitals without such facilities (46.1%; OR 0.73, 95% CI 0.48 to 1.10), even in lytic-eligible patients (33% vs. 31%; OR 1.10, 95% CI 0.63 to 1.91), although primary angioplasty has been used more frequently (25.7% vs. 1.9%; OR 18.2, 95% CI 6.92 to 47.65). Nevertheless, hospital mortality for patients with an in-hospital AMI was similar at both types of hospitals (26.5% vs. 27.7%; OR 0.94, 95% CI 0.59 to 1.50), as well as for the combined end point (33.1% vs. 34.5%; OR 0.94, 95% CI 0.61 to 1.46). However, the high mortality rate of patients with an in-hospital AMI, in combination with the relative low use of reperfusion therapy, even at hospitals with the facilities to perform angioplasty, should encourage each hospital to review their cases and to try to improve the management of these patients.

In-hospital infarction as a clinical model of the population view of case fatality in patients with AMI.   The observed case fatality rate of 27.3% for patients with an in-hospital AMI is much lower than the 50% case fatality rate for the population reported by the Multinational MONitoring of Trends and Determinants in CArdiovascular Disease (MONICA) project (1), but it is also higher than the 13.9% case fatality rate for patients with a prehospital AMI reaching the hospital alive in our study. As L’Abbate et al. (10) showed, this relatively low mortality rate for patients with an in-hospital AMI can be attributed to the proportion of patients who had a cardiac arrest and were successfully resuscitated. However, we found no difference in the number of resuscitated patients between in-hospital AMI and prehospital AMI (8.3% vs. 6.3%; OR 1.30, 95% CI 0.84 to 2.01). However, the in-hospital AMI subgroup may not be representative of the population developing AMI. A majority of patients with an in-hospital AMI might be admitted with preexisting clinical evidence of ischemic heart disease or may be suffering from other clinically relevant diseases, which made hospital admission necessary. Another possible explanation for the still high mortality might be that electrical instability may be responsible for a smaller than expected proportion of sudden deaths outside the hospital, as well as a higher rate than expected due to left ventricular failure or shock.

Study limitations.   Admission diagnosis was evaluated retrospectively in only 88 (21.8%) of 403 patients with an in-hospital AMI. Therefore, the reported percentages are giving only an impression of the categories of patients with an in-hospital AMI. We also did not collect information on the proportion of patients with postprocedural (coronary balloon angioplasty, stents) in-hospital AMI. In contrast to the MONICA project, we collected only information of clinically diagnosed AMIs, not of all patients who died suddenly during their hospital stay and were not treated at the intensive care unit.

Conclusions.   In-hospital infarction, which comprises up to 7% of all AMIs, is a poorly analyzed entity. Most patients with an in-hospital infarction (72.8%) are admitted because of stable or unstable angina pectoris. Mortality and morbidity are high in patients with an in-hospital AMI, even after adjusting for other confounding variables. Contraindications for thrombolysis are more prevalent in these patients; however, primary angioplasty, which should be the method of choice in these circumstances, is currently underused.

	Footnotes

 
This study was supported in part by Zeneca, Bristol Myers-Squibb, Ministerium für Gesundheit, Arbeit, Soziales des Landes Rheinland-Pfalz, Landesversicherungsanstalt Rheinland-Pfalz, Barmer und Betriebskrankenkassen Rheinland-Pfalz.

	References

Top Abstract Methods Results Discussion References

 

1. WHO MONICA ProjectChambless L, Keil U, Dobson A, Mähönen M, et al. Population versus clinical view of case fatality from coronary heart disease: results from the WHO MONICA Project 1985–1990. Circulation. 1997;96:3849–3859[Abstract/Free Full Text]
2. United Kingdom Heart Attack Study Collaborative GroupNorris RM. Fatality outside hospital from acute coronary events in three British health districts: 1994–1995. BMJ. 1998;316:1065–1070[Abstract/Free Full Text]
3. Task Force of the European Society of Cardiology and the European Resuscitation Council. The pre-hospital management of acute heart attacks. Eur Heart J. 1998;19:1140–1164[Free Full Text]
4. Tarhan S, Moffit EA, Taylor WF, Guiliani ER. Myocardial infarction after general anesthesia. JAMA. 1972;220:1451–1454[CrossRef][Medline]
5. Mauney FM, Ebert PA, Sabiston DC. Postoperative myocardial infarction: a study of predisposing factors, diagnosis and mortality in a high risk group of surgical patients. Ann Surg. 1970;172:497–503[Medline]
6. Dack S. Postoperative myocardial infarction. Am J Cardiol. 1963;12:423–430[Medline]
7. Schühlen H, Kastrati A, Dirschinger J, et al. Intracoronary stenting and risk for major adverse cardiac events during the first month. Circulation. 1998;98:104–111[Abstract/Free Full Text]
8. Lincoff AM, Topol EJ, Chapekis AT, et al. Intracoronary stenting compared with conventional therapy for abrupt vessel closure complicating coronary angioplasty: a matched case-control study. J Am Coll Cardiol. 1993;21:866–875[Abstract]
9. Zmyslinski RW, Lackland DT, Keil JE, Higgins JE. Increased fatality and difficult diagnosis of in-hospital acute myocardial infarction: comparison to lower mortality and more easily recognized pre-hospital infarction. Am Heart J. 1981;101:586–592[Medline]
10. L’Abbate A, Carpeggiani C, Testa R, Michelassi C, Biagini A, Severine S. In-hospital myocardial infarction: pre-infarction features and their correlation with short-term prognosis. Eur Heart J. 1986;7:53–61
11. MITRA Study GroupSchuster S, Koch A, Burczyk U, et al. Therapy of acute myocardial infarction: impact of clinical trials on clinical practice—the MITRA pilot phase. Z Kardiol. 1997;86:273–283[CrossRef][Medline]
12. Barron HV, Bowlby LJ, Breen T, et al. Use of reperfusion therapy for acute myocardial infarction in the United States: data from the National Registry of Myocardial Infarction-2. Circulation. 1998;97:1150–1156[Abstract/Free Full Text]
13. Wagner S, Schneider S, Schiele R, et al. Acute myocardial infarction in Germany between 1996 and 1998: therapy and intrahospital course—results of the Myocardial Infarction Registry (MIR) in Germany. Z Kardiol. 1999;88:857–867[CrossRef][Medline]
14. Primary Angioplasty in Myocardial Infarction (PAMI) InvestigatorsStone GW, Grines CL, Browne KF, et al. Outcome of different reperfusion strategies in patients with former contraindications to thrombolytic therapy: a comparison of primary angioplasty and tissue plasminogen activator. Cathet Cardiovasc Diagn. 1996;39:333–339[CrossRef][Medline]
15. Waldecker B, Waas W, Heizmann H, et al. PTCA for acute myocardial infarction in patients not eligible for iv thrombolysis: in-hospital results. Fibrinolysis. 1995;9(Suppl 1):126–128
16. Himbert D, Juliard J, Steg G, et al. Primary angioplasty for acute myocardial infarction with contraindication to thrombolysis. Am J Cardiol. 1993;71:377–381[CrossRef][Medline]
17. McCullough PA, O’Neill WW, Graham M, et al. A prospective randomized trial of triage angiography in acute coronary syndromes ineligible for thrombolytic therapy: results of the Medicine versus Angiography in Thrombolytic Exclusion (MATE) trial. J Am Coll Cardiol. 1998;32:596–605[Abstract/Free Full Text]
18. Maximal Individual Therapy in Acute Myocardial Infarction (MITRA) Study GroupZahn R, Schuster S, Schiele R, et al. Comparison of primary angioplasty with conservative therapy in patients with acute myocardial infarction and contraindications for thrombolytic therapy. Cathet Cardiovasc Intervent. 1999;46:127–133[CrossRef][Medline]
19. Liem AL, van’t Hof AWJ, Hoorntje CA, de Boer MJ, Suryapranata H, Zijlstra F. Influence of treatment delay on infarct size and clinical outcome in patients with acute myocardial infarction treated with primary angioplasty. J Am Coll Cardiol. 1998;32:629–633[Abstract/Free Full Text]
20. Zijlstra F, van’t Hof AWJ, Liem AL, Hoorntje CA, Suryapranata H, de Boer MJ. Transferring patients for primary angioplasty: a retrospective analysis of 104 selected high risk patients with acute myocardial infarction. Heart. 1997;78:333–336[Abstract/Free Full Text]
21. van’t Hof AWJ, Liem A, Suryapranata H, Hoorntje JCA, de Boer MJ, Ziljstra F. Clinical presentation and outcome of patients with early, intermediate and late reperfusion therapy by primary angioplasty for acute myocardial infarction. Eur Heart J. 1998;19:118–123[Abstract/Free Full Text]
22. Bellinger RL, Califf RM, Mark DB, et al. Helicopter transport of patients during acute myocardial infarction. Am J Cardiol. 1988;61:718–722[CrossRef][Medline]
23. Gore JM, Corrao JM, Goldberg RJ, et al. Feasibility and safety of emergency interhospital transport of patients during early hours of acute myocardial infarction. Arch Intern Med. 1989;149:353–355[Abstract]

This article has been cited by other articles:

				C. Maynard, E. Lowy, J. Rumsfeld, A. E. Sales, H. Sun, B. Kopjar, B. Fleming, R. L. Jesse, R. Rusch, and S. D. Fihn The prevalence and outcomes of in-hospital acute myocardial infarction in the department of veterans affairs health system. Arch Intern Med, July 10, 2006; 166(13): 1410 - 1416. [Abstract] [Full Text] [PDF]

This Article Abstract Figures Only Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Zahn, R. Search for Related Content PubMed PubMed Citation Articles by Zahn, R.