Acute Myocardial Infarction: Difference in the Treatment between Men and Women

Transcription

1 Quality Assurance in Hcahh Can, Vol. 5, No. 3, pp ,1993 Printed in Great Britain /93 $ Pergamon Press Ltd Acute Myocardial Infarction: Difference in the Treatment between Men and Women MEKAEL DELLBORG and KARL SWEDBERG Department of Medicine, (5stra Hospital, University of GGteborg, S Gdteborg, Sweden During the last decade, treatment of myocardial infarction has changed and the prognosis dramatically improved. A sex bias in considering revascularization in men and women with coronary heart disease has been reported. The influence of gender on treatment given to patients with an acute myocardial infarction has not been investigated. From 1989 to 1991 there were 1515 patients with acute myocardial infarction admitted to the coronary care unit at Ostra Hospital; 67% were men. Pharmacological treatment limiting infarct size was given to 60% of all women and to 67% of all men;;? < In addition, coronary angiography during the hospital stay was performed in 0.2% of all women vs 1.9% of all men; p < The prevalence of diabetes, age, symptoms or prehospital delay cannot explain these findings. While a sex bias in referring patients for revascularization has been reported, this report also describes a possible sex bias in the pharmacological treatment of acute myocardial infarction. Key words: Acute myocardial infarction, treatment, gender, coronary angiography, thrombolysis INTRODUCTION During the last decade, treatment of myocardial infarction has changed markedly. The introduction of intravenous /J-blockade, intravenous nitroglycerine and thrombolysis has dramatically improved the prognosis for patients with acute myocardial infarction [1]. Several studies have indicated that women have a higher short-term mortality in acute myocardial infarction as compared to men [2-4]. This difference has been partly explained by differences in age and in the occurrence of diabetes [4,5]. Recently, several reports have focused on the occurrence of a sex bias in considering angiography and revascularization in men and women with coronary heart disease [6,7]. A higher prevalence of diabetes, a higher mean age and a longer delay before seeking medical attention may explain some of the excess mortality observed in women suffering from an acute myocardial infarction. However, the influence of gender on treatment given has not been investigated. PATIENTS AND METHODS Ostra Hospital is a university hospital that serves a community of 250,000 inhabitants. The coronary care unit has eight intensive care beds and 14 step down beds with one-channel electrocardiographic (ECG) monitoring. Since 1984 a computerized data base has been used and all patients admitted to the coronary care unit are entered into this data base. For each patient a one-page data form isfilledout by the attending nurse. The form contains the times of onset of symptoms, admission to hospital and arrival in the coronary care unit. Mode of transportation, pre-hospital events, previous morbidity, risk factors (smoking, hypertension, diabetes) and principal symptoms that caused the patient to be admitted to the coronary care unit are noted. Finally, complications, interventions and discharge diagnosis are noted when the patient is discharged from hospital. Diagnosis of acute myocardial infarction A diagnosis of acute myocardial infarction is made when two out of three of the following criteria are fulfilled: First submitted 10 January 1993; accepted for publication 16 February

2 262 M. Dellborg and K. Swedberg TABLE 1. Clinical characteristics, type and location of infarction N Men (%) Women N (%) P Diabetes mellitus Previous infarction Pre-hospital delay <6 hr Infarct location/type Anterior Inferior Unlocalized Q-wave AMI Prehospital delay, time from onset of symptoms until die patient arrives in the hospital. AMI, acute myocardial infarction., not significant. 1. A history strongly suggestive of acute ischemic heart disease. 2. A rise in cardiac enzymes (at least two values above the normal limit). 3. Typical ECG evolution with ST-changes evolving into T-wave inversions with or without Q-wave evolution. The diagnosis may also be based on autopsy findings. Treatment of myocardial infarction Since 1984 routine treatment with intravenous /J-blockers has been given. The treatment schedule suggests treating all patients without contra-indications with immediate intravenous ^-blockage when a diagnosis of acute myocardial infarction is suspected. Intravenous nitroglycerine has been used routinely since Our policy has been to use nitroglycerine as adjunctive therapy for patients with chest pain that is responding poorly to analgesics and/or ^-blockage and also for patients with concomittant left ventricular failure. For patients given neither /3-blockade nor thrombolytic drugs, our policy is to give at least 24 hr of treatment with intravenous nitroglycerine in the hope of limiting infarct size. Thrombolytic treatment is given to patients with less than 6 hr duration of symptoms and with ST-segment elevation or bundle branch block. Usual contraindications to thromborysis are applied. The treatment protocol for intravenous ^-blockade, intravenous nitroglycerine and thrombolytic drugs has not changed during The treatment regimes are laid out in a treatment protocol used for all patients admitted to the coronary care unit. Statistics Continuous variables were compared between groups using Student's f-test. Proportions were compared using 4x4 table test. A/7-value of <0.05 was considered significant. RESULTS From 1 January 1989 to 31 December 1991 there were 4581 patients admitted to the coronary care unit. Of these, 1515 were given a final diagnosis of acute myocardial infarction; 1022 (67%) were men and 493 women. Background characteristics, localization and type of infarct are given in Table 1. Women were on average 6 years older than men (72 ± 13 vs 66 ± 14 years, p < 0.01) and they had almost 70% higher mortality during the hospital stay (see Table 2). The use of temporary pacemakers, echocardiography and Swan-Ganz catheterization is shown in Table 2. Coronary angiography during the hospital stay was performed significantly more often in men; only rarely was it performed in women. Inotropic drugs (mostly dobutamine and dopamine) were used in 10.1% of all patients and more frequently in women (see Table 3). Pharmacological treatment limiting infarct size was given to 64% of all patients; however, women were given significantly less treatment, i.e. less thrombolytic drugs, intravenous ^-blockade and intravenous nitroglycer-

3 Sex Bias in Acute Myocardial Infarction Treatment 263 TABLE 2. Interventions and complications daring the hospital stay Men N Women N Coronary angiography Temporary pacemaker Swan-Ganz catheterization Echocardiography Mortality , not significant. TABLE Thrombolytic drugs I.V. nitroglycerin I.V. 0-blockade Inotropic drugs I.V., intravenous. 3. Pharmacological treatment Men N -I w Women N (%) P ine (see Table 3). The proportion of patients not given any infarct size-limiting therapy was 40% for women versus 33% for men (p < 0.05). There were 458 patients less than 65 years of age (374 men, 84 women). Among these younger patients, women were given significantly less intravenous nitroglycerine as compared to men (32% versus 45%, p < 0.05) as well as less intravenous ^-blockade (35% versus 47%, p = 0.054). Also, for thrombolytic drugs there was a tendency for women to receive less than men although the difference was not statistically significant (44 versus 47%, ). Among patients less than 65 years of age, coronary angiography during the hospital stay was performed in nine out of 374 men (2.4%) while it was not performed in any women in this age group (). DISCUSSION Recently, it was reported that women who are hospitalized for coronary heart disease undergo fewer diagnostic and therapeutic procedures than men, i.e. are less frequently referred for coronary angiography, coronary angioplasty or by-pass surgery [6-8]. In our study, women were less likely to receive thrombolytic drugs, intravenous nitroglycerine or intravenous ^-blockade, as well as coronary angiography. This may be explained by a sex bias also in selecting treatment during the acute phase of an acute myocardial infarction. Since the institution of these treatments may be influenced by age one might expect a difference in mean age to result in a difference in the proportions of men and women treated with infarct size-limiting drugs. However, we found the most pronounced difference between the sexes in patients less than 65 years of age. Furthermore, there are no reports that women would benefit less from infarct size-limiting therapy [9,10] and thus no scientific support of a gender difference in treatment of acute myocardial infarction as found in the present study. Women have repeatedly been found to have a higher hospital mortality when suffering an acute myocardial infarction [2-4,11]. However, mortality in acute myocardial infarction is strongly age dependent [12] and we, as well as others, have found women to be older than men hospitalized for acute myocardial infarction. While some authors have found the higher mortality of women to be largely dependent upon their higher mean age [2,11], others have concluded that also when adjusting for age and diabetes, female mortality remains higher than male in acute myocardial infarction. In the

4 264 M. Dellborg and K. Swedberg present study, the difference in mean age between men and women will explain a significant part of the difference in mortality. Women have been reported to have a longer pre-hospital delay when suffering chest pain [13]. We confirmed this observation (data not shown), but the proportion of patients admitted within 6 hr of onset of chain pain (i.e. within the time limit for receiving thrombolytic therapy) was similar among men and women. Diabetes is a strong risk factor for coronary heart disease and will also increase the shortterm mortality during hospital stay in patients with acute myocardial infarction. Several authors report a higher incidence of diabetes among women [3,4] while others have found smaller non-significant differences [2]. We found only a small non-significant difference in the prevalence of diabetes between men and women. However, it has been pointed out that diabetes is a stronger risk factor among women as compared to men. Therefore, even small differences in the prevalence of diabetes may produce larger than expected differences in mortality [5]. In the present study, chest pain was by far the most common symptom for admission: occurrence was about 85% in both sexes. In the Multicenter Chest Pain Study, it was found that older patients with acute myocardial infarction were less likely to have radiation of pain to the jaw, neck, left arm and left shoulder, but on the other hand older patients were less likely to have pain reproduced by deep breathing or changes in position, as compared to younger patients [14]. Thus, there seems to be no clear cut difference in older versus younger or in male versus female patients in the clinical presentation of an acute myocardial infarction. The standard 12-lead electrocardiogram has a central role in the early diagnosis of an acute myocardial infarction, and the decision to institute the thrombolytic treatment is based on ECG findings (and clinical symptoms). We have found no reports regarding sex difference in ECG changes during myocardial infarction. Since patients admitted to the coronary care unit are selected partly on ECG findings, any data regarding the magnitude of ischemic ECG changes in men and women would be difficult to interpret. In conclusion, women are less likely to receive infarct size-limiting drug therapy as well as coronary angiography during the hospital stay. The prevalence of diabetes, age, symptoms or prehospital delay cannot explain these findings. While a sex bias in referring patients for coronary angiography and revascularization has been reported previously, this report also described a possible sex bias in the pharmacological treatment of acute myocardial infarction. Acknowledgements: The assistance of the staff at the coronary care unit at Ostra Hospital, in particular Ms Lena Liman and Ms Monica Jacobsson, is gratefully acknowledged. We also acknowledge Martin Riha, PhD who designed uie data base. We also thank Ms Gunnel Johansson for preparing the manuscript. REFERENCES 1. Yusef S, Wittes J and Friedman, L, Overview of results of randomized clinical trials in heart disease. JAMA 260: 2088, Dittrich H, Gilpin E, Nicod P, Cali G, Henning H and Ross J, Acute myocardial infarction in women: influence of gender on mortality and prognostic variables. Am J Cardiol 62: 1, Tofler G, Stone P, Muller J et al., Effects of gender and race on prognosis after myocardial infarction: adverse prognosis for women, particularly black women. J Am Coll Cardiol 9: 473, Greenland P, Reicher-Reiss H, Goldbourt U and Behar S, In-hospital and 1-year mortality in 1,524 women after myocardial infarction. Circulation 83: 484, Barrett-Connor E, Cohn B, Wingard D and Edelstein S, Why is diabetes mcllitus a stronger risk factor for fatal ischemic heart disease in women than in men? JAMA 265: 627, Ayanian J and Epstein A, Differences in the use of procedures between women and men hospitalized for coronary heart disease. N Engl J Med 325: 221, Steingart R, Packer M, Hamm P et al., Sex differences in the management of coronary artery disease. N Engl J Med 325: 226, Tobin, J, Wassertheil-Smoller S, Wexler J et al., Sex bias in considering coronary bypass surgery. Ann Intern Med 107: 19, Clyne C, Antitiirombotic therapy in the primary and secondary prevention of coronary-related death and infarction: focus on gender differences. Cardiology TJ: 99, Becker R, Coronary thrombolysis in women. Cardiology TJ: 110, Robinson K, Conroy R, Mulcahy R and Hickey N, Risk factors and in-hospital course of first episode of myocardial infarction or acute coron-

5 Sex Bias in Acute Myocardial Infarction Treatment 265 ary insufficiency in women. / Am Coll Cardiol 11: 932, Weaver D.LitwinP, Martin Jet al., Effect of age on use of thrombolytic therapy and mortality in acute myocardial infarction. / Am Coll Cardiol 18: 657, Moss A, Wynar B and Goldstein S, Delay in hospitalization during the acute coronary period. Am J Cardiol 24: 659, Solomon C, Lee T, Cook F et al., Comparison of clinical presentation of acute myocardial infarction in patients older than 65 years of age to younger patients: the multicenter chest pain study experience. Am J Cardiol 63: 772,1989.

6