Treatment of Acute Myocardial Infarction by Primary Coronary Angioplasty or Intravenous Thrombolysis in the “Real World”
One-Year Results From a Nationwide French Survey
Background—Recent randomized trials comparing primary coronary angioplasty and intravenous thrombolysis at the acute stage of myocardial infarction have shown a limited but definite advantage for primary angioplasty. The aim of this study was to document 1-year outcome in patients receiving either thrombolysis or primary angioplasty for acute myocardial infarction in the “real world.”
Methods and Results—We used a nationwide prospective registry of all patients admitted for acute myocardial infarction in French intensive care units in November 1995. Of the 721 patients who received reperfusion therapy, 152 were treated with primary angioplasty and 569 received intravenous thrombolysis. The two groups were remarkably similar with respect to all baseline descriptors, except that a higher proportion of patients in the angioplasty group had a history of cerebrovascular accident (10% versus 2%, P<0.01). In-hospital outcome was not different in the 2 groups. One-year survival was 85.5% in the angioplasty group and 89.5% in the thrombolysis group (P=0.18). Multivariate analysis showed that older age, anterior location of infarction, female sex, and history of heart failure were related to 1-year mortality. In patients alive on day 5, the use of primary angioplasty and higher Killip class were additional adverse prognostic indicators.
Conclusions—The results of this large registry of real-world practice indicate no survival benefit for patients treated with primary angioplasty compared with those who received thrombolytic therapy.
There is increasing evidence from randomized trials that primary coronary angioplasty yields significantly better results than intravenous thrombolysis for the treatment of acute myocardial infarction.1 2 3 4 As in many randomized prospective studies, however, the patients included in these trials represent only a small proportion of those actually treated with either of these methods, and the centers participating in the trials can be considered particularly experienced and motivated. Therefore, whether the results of such randomized studies can apply to the “real world” of clinical cardiology remains a matter of debate and is of major importance in terms of public health policies: if a substantial clinical benefit from primary coronary angioplasty could be demonstrated on the scale of a whole country, it might be necessary to open an evenly distributed network of catheterization laboratories and have them operated by properly trained personnel, which would represent a tremendous economic burden for society. The Myocardial Infarction Triage and Intervention (MITI) registry5 failed to demonstrate any significant advantage for primary coronary angioplasty in a population of patients admitted to the participating Seattle hospitals from 1988 to 1994. In the MITI registry, however, >25% of the patients who received thrombolysis also had angioplasty on the day of admission (rescue angioplasty), a rate that appears high and may have considerably influenced the outcome of the patients treated with thrombolysis. The present study is a prospective, observational survey designed to assess the current in-hospital management of acute myocardial infarction in intensive care units in France by the end of 19956 and to analyze the results achieved in terms of early and late (1-year) mortality. The aim of the present study was to analyze the outcome of all patients who had received early reperfusion therapy by either intravenous thrombolysis or coronary angioplasty.
Patient selection and data collection have been described previously.6 Briefly, all patients with acute myocardial infarction (<48 hours from symptom onset) admitted during the month of November 1995 to 373 of the 501 intensive care units accustomed to treating patients for acute myocardial infarction were included. From the 373 units that participated in the initial survey, 312 (84%) agreed to participate in a 1-year follow-up study of the patients initially included. All patients admitted within 6 hours of the onset of chest pain and treated with either intravenous thrombolysis or primary coronary angioplasty (PTCA), defined as PTCA performed within 24 hours of hospital admission without previous or concomitant use of thrombolytic therapy, were included in the present study.
Baseline characteristics and medical data, including treatments prescribed during the first 5 days after hospital admission, were collected by 1 investigator in each center.
The patients’ cardiovascular history, their risk factors (smoking status, history of hypertension or treated hypertension, cholesterol level >2.5 g/L or treated hyperlipidemia, family history, diabetes mellitus), their clinical course over the first 5 days after admission, including maximal Killip class, and the initial diagnostic and therapeutic management were recorded for each patient. Furthermore, left ventricular ejection fraction (LVEF) assessed at any time during the first 5 days was recorded. The value for LVEF that was used for the present analyses was determined by the following priority ranking of the method used: (1) LV contrast angiography, (2) radionuclide angiography, (3) echocardiography using Simpson’s method, (4) echocardiography using the Berning wall motion index,7 and (5) echocardiography with visual estimation of LVEF. For the present analyses, LVEF was categorized into 4 groups: 1, >50%; 2, from 36% to 50%; 3, from 21% to 35%; and 4, ≤20%.
Follow-up data were obtained by telephone or direct interviews of the patients and/or their referring physicians. They specifically assessed the use of revascularization procedures (coronary angioplasty or coronary bypass surgery) and mortality during the year after the index hospitalization.
Continuous variables are described as mean±SD. Time from onset of symptoms to hospital admission is expressed as median and quartiles. Comparisons between groups were made by use of unpaired t tests for continuous variables and χ2 tests for discrete variables. One-year probability of survival was calculated according to the Kaplan-Meier method. Cox regression analysis was used to assess the independent prognostic value of baseline parameters. Variables with a value of P<0.20 on univariate analyses were included in the multivariate models. Two sets of analyses were performed: (1) a model including clinical ECG variables at entry and initial modality of treatment with primary PTCA or intravenous thrombolysis, tested on all patients initially admitted, and (2) a model applied only to the patients who were alive on day 5, including baseline clinical and ECG parameters, modality of initial treatment, worst Killip class, and LVEF determined during the first 5 days, as well as medications administered during the first 5 days. For all tests, a value of P<0.05 was considered significant.
At the 312 centers that agreed to participate in the follow-up study, 2152 patients had been admitted for acute myocardial infarction during the month of November 1995. Of these, 735 were admitted within 6 hours of the onset of chest pain and were treated with either primary coronary angioplasty or intravenous thrombolysis; 1-year follow-up data were available for 721 of these patients (98%). Compared with patients who did not receive reperfusion therapy (Table 1⇓), patients treated with either thrombolysis or primary PTCA were younger and more often women; among risk factors, hypertension and diabetes mellitus were more prevalent in patients who had no reperfusion therapy, whereas more patients undergoing reperfusion therapy were current smokers or had known hyperlipidemia. More patients in the reperfusion therapy group had Q-wave and/or anterior-wall myocardial infarction. In contrast, patients who had no reperfusion therapy more often had a history of previous myocardial infarction, heart failure, or cerebrovascular accident.
Intravenous thrombolysis was administered to 569 patients, and 152 had primary coronary angioplasty. The baseline characteristics of the patients according to the initial therapeutic option are detailed in Table 2⇓. There was no significant difference between the 2 groups with regard to demographic data, risk factors, medical history, or type or location of myocardial infarction. More patients in the primary angioplasty group, however, had a history of cerebrovascular accident. The median time from symptom onset to hospital admission was similar in the 2 groups.
Management of Patients, Events During the First 5 Days, and 30-Day Mortality
The complications over the first 5 days and the medications prescribed at any time during this period are listed in Table 3⇓. Five-day mortality was 5.6% in the lysis group and 6.6% in the primary PTCA group (P=NS). The proportions of patients with Killip class >1 at any time within the first 5 days were similar in the 2 groups.
The use of β-blockers, ACE inhibitors, diuretics, and digitalis was similar in the 2 groups, and calcium antagonists and lipid-lowering medications were prescribed more often in patients undergoing primary angioplasty. Fifty-three patients in the thrombolysis group (9%) had rescue angioplasty, defined as angioplasty performed within 24 hours of hospital admission. Nonaspirin antiplatelet therapy was used in 6% of patients with intravenous thrombolysis (4% in those without rescue angioplasty and 23% in patients with rescue angioplasty) and 33% of patients with primary angioplasty, reflecting the use of ticlopidine in patients with stent implantation.
At 30 days, mortality was 7.6% in the thrombolysis group, compared with 9.2% in the primary PTCA group (P=NS).
The overall probability of survival at 1 year was 89.5% in the thrombolysis group and 85.5% in the primary PTCA group (P=0.18) (Figure⇓). In the primary PTCA group, 1-year survival was similar in those who had received nonaspirin antiplatelet therapy (patients treated with stents) (84%) and in those who did not receive such medications (conventional angioplasty) (86%); in addition, the 1-year probability of survival was identical for patients who had been treated in centers that had performed ≤3 versus ≥4 primary PTCA procedures during the study period (85% versus 86%, respectively).
At 1 year, 55 patients of the primary PTCA group (36%) and 292 of the thrombolysis group (51%) had had ≥1 myocardial revascularization procedure (including rescue angioplasty for patients in the thrombolysis group) (P<0.005). By univariate analyses, age, female sex, history of myocardial infarction, history of heart failure, anterior location of myocardial infarction, and presence of peripheral vascular disease were associated with increased mortality, whereas current smoking was associated with improved survival. By multivariate adjustment, only age, history of heart failure, anterior location of infarction, and female sex were significant adverse prognostic factors; the use of primary PTCA was not a significant predictor of outcome (Table 4⇓). In the patients who were alive on day 5, there were 4 independent predictors of 1-year outcome: age, Killip class during the first 5 days, history of heart failure, and use of primary PTCA; when medications administered during the first 5 days were added to the model, the use of β-blocking agents was associated with improved survival (relative risk, 0.31; 95% CI, 0.14 to 0.70) (Table 5⇓).
Randomized trials and registries describing current practices and outcomes bring different types of information. Randomized trials of interventions are necessary to document the efficacy of a given type of therapy or intervention in an optimal setting. There is always, however, a major selection bias in selecting the patients, and only a small minority of the patients presenting with a given condition are included in such trials. This brings legitimate concern as to the applicability of the results of these trials on a larger scale. Recently, it has been shown that patients who met the selection criteria for inclusion into a randomized trial of PTCA versus coronary surgery fared better than those actually randomized, which casts doubt on the applicability of such randomized trials in clinical practice.8 In contrast, registries can document whether new therapeutic modalities used in the real world are correlated with improved clinical outcomes. They also have, however, evident methodological biases, and in particular they raise the concern of the comparability of different groups of patients receiving different kinds of treatment.
Because of the limitations of both types of studies, however, it appears essential to consider them complementary for clinical decision making. When both give concordant results, their clinical applicability can be regarded as extremely likely. When the results are conflicting, further evaluation is necessary before we can definitely recommend any specific management policy.
Compared with the patients included in the randomized trials of primary angioplasty versus surgery, our population is older, which can explain in part the higher in-hospital mortality observed in our patients treated with primary angioplasty. In contrast, they appear to be similar to those reported in a German registry of direct coronary angioplasty at the acute stage of myocardial infarction.9 In the thrombolysis group, 30-day mortality was in the range of that observed in the clinical trials studying the efficacy of thrombolytic therapy at the acute stage of myocardial infarction.10 11 12 13 14 15 16 17 18 19
Although the present study is subject to the same methodological limitations as any registry, the groups receiving either thrombolysis or primary PTCA are strikingly similar with regard to all available baseline descriptors. The only difference was the higher prevalence of cerebrovascular accidents in patients treated with primary angioplasty, a finding that most probably reflects the contraindication for the use of thrombolysis in such patients. Despite this, it cannot be excluded that patients undergoing primary PTCA might have had clinical signs of severity that escaped the usual clinical descriptors taken into account in the present study; for instance, there was a small, not significant, excess of patients in Killip class IV (7.9% versus 5.4%) among the patients who had primary PTCA. Furthermore, it was not possible from our data to determine how many of the patients treated with primary angioplasty had authentic contraindications to thrombolysis. In addition, although we included only patients who were admitted within 6 hours of the onset of chest pain, PTCA was actually performed later in many patients, at a time when little benefit might be expected from the procedure with regard to preservation of LV function.20 Whatever the case, however, multivariate adjustments failed to show any advantage for primary PTCA in terms of 1-year survival, and the use of primary PTCA was even significantly correlated with a poorer outcome in patients alive on day 5.
These results are in keeping with those of the MITI registry,5 which found no benefit for primary angioplasty up to 3 years after the initial episode of myocardial infarction. As in our population, the 2 groups in the MITI registry were well balanced, but the rate of rescue angioplasty in patients receiving thrombolytic treatment was 26%, compared with only 9% in our study. The MITI registry included patients treated between 1988 and 1994, and angioplasty technique has undoubtedly improved since then. In our population of patients treated by the end of 1995, the angioplasty technique was quite similar to that currently used, and the use of coronary stenting as estimated from the prescription of nonaspirin antiplatelet therapy was substantial, representing ≈30% of the patients treated with primary angioplasty. It is possible, however, that a policy of systematic stenting during primary PTCA might have improved the results in the PTCA group,21 although the German registry of direct angioplasty failed to document the superiority of coronary stenting in this setting.9 Despite these differences, the similarities in the findings in the 2 registries are striking. One-year survival was slightly lower than that observed in the MITI registry (89% for thrombolysis and 85% for primary PTCA) but was consistent with the fact that our population was slightly older. Beyond the initial hospital stage, there was no difference in the use of revascularization procedures over 1 year. Although revascularization procedures were used less often in the MITI registry, past the initial hospital admission, there was also no difference at 3 years between patients initially treated with thrombolysis or PTCA. More recently, a report from the Second National Registry of Myocardial Infarction (NRMI-2) on patients enrolled in the United States in 1994 and 1995 also showed that, in the routine clinical setting, thrombolysis using recombinant tissue plasminogen activator (rtPA) yielded in-hospital results that were similar to those of primary angioplasty (in-hospital mortality, 5.4% after rtPA versus 5.2% after primary angioplasty) when patients in cardiogenic shock were excluded.22
The predictors of 1-year outcome in our population of comparatively young patients who received reperfusion therapy at the acute stage of myocardial infarction were expected and were very similar to those evidenced in the MITI registry: older age, female sex, anterior location of myocardial infarction, and previous history of heart failure. In patients alive on day 5, after multivariate adjustment, the use of primary angioplasty was an adverse prognostic factor, whereas the early use of β-blocking agents was associated with improved survival.
The reasons for the discrepancies between randomized studies and registries are unclear; motivation for participating in a randomized trial as well as center experience, which has been shown to influence the results of direct angioplasty at the acute stage of myocardial infarction,23 might constitute a partial explanation, although we failed to document a difference in outcome between centers that had performed ≤3 angioplasty cases and those that had performed ≥4 cases during the 1-month recruitment period of our study.
On the whole, the results of the present survey are concordant with those of the few other registries comparing primary angioplasty and intravenous thrombolysis at the acute stage of myocardial infarction, and they fail to document any additional benefit associated with the use of the former mode of therapy. Therefore, any attempt at developing a health policy promoting the routine use of coronary angioplasty at the acute stage of myocardial infarction should probably be regarded as premature. In contrast, it appears that too many patients admitted to an intensive care unit for acute myocardial infarction, among whom a number, such as elderly patients, are at increased risk, are still treated conservatively (ie, without thrombolysis or angioplasty) when they would probably benefit from reperfusion therapy. Lastly, there is no justification from the present study to delay hospital admission for the sole purpose of bringing a patient to an institution capable of performing primary coronary angioplasty, and care should also be taken not to delay the initiation of thrombolytic treatment in institutions that offer both treatment options.24
This study was supported by a grant from Laboratoires Roussel, France. The authors wish to acknowledge the support of all cardiologists from the participating institutions, a list of which has been published previously.6
- Received December 2, 1998.
- Revision received March 9, 1999.
- Accepted March 9, 1999.
- Copyright © 1999 by American Heart Association
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Gruppo Italiano per lo Studio della Sopravvivenza nell’Infarto Miocardico. GISSI-2: a factorial randomised trial of alteplase versus streptokinase and heparin versus no heparin among 12,490 patients with acute myocardial infarction. Lancet. 1990; 336: 65–71.
ISIS 3 (Third International Study of Infarct Survival collaborative group). A randomised comparison of streptokinase vs tissue plasminogen activator vs anistreplase and aspirin plus heparin vs aspirin alone among 41,299 cases of suspected acute myocardial infarction. Lancet. 1992;339:753–770.
Fibrinolytic Therapy Trialists’ (FTT) collaborative group. Indications for fibrinolytic therapy in suspected acute myocardial infarction: collaborative overview of early mortality and major morbidity results from all randomised trials of more than 1000 patients. Lancet. 1994;343:311–322.
ISIS-4 (Fourth International Study of Infarct Survival) collaborative group. ISIS-4: a randomised factorial trial assessing early oral captopril, oral mononitrate, and intravenous magnesium sulphate in 58,050 patients with suspected acute myocardial infarction. Lancet. 1995;345:669–685.
Tebbe U, Michels R, Adgey J, Boland J, Caspi A, Charbonnier B, Windeler J, Barth H, Groves R, Hopkins GR, Fennel W, Betriu A, Ruda M, Mlczoch J, for the Comparison Trial of Saruplase and Streptokinase Investigators. Randomized, double-blind study comparing saruplase with streptokinase therapy in acute myocardial infarction: the COMPASS equivalence trial. J Am Coll Cardiol. 1998;31:487–493.
Brodie BR, Stuckey TD, Wall TC, Kissling G, Hansen CJ, Munsy DB, Weintraub RA, Kelly TA. Importance of time to reperfusion for 30-day and late survival and recovery of left ventricular function after primary angioplasty for acute myocardial infarction. J Am Coll Cardiol. 1998;32:1312–1319.
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