Frequency of use of thrombolytic therapy in acute myocardial infarction in Israel

Does magnesium have a role in the treatment of patients with coronary artery disease?

Hypomagnesemia is common in hospitalized patients, especially in elderly patients with coronary artery disease (CAD) and/or those with chronic heart failure. Hypomagnesemia is associated with increased all cause mortality and mortality from CAD. Magnesium supplementation improves myocardial metabolism, inhibits calcium accumulation and myocardial cell death; it improves vascular tone, peripheral vascular resistance, afterload and cardiac output, reduces cardiac arrhythmias and improves lipid metabolism. Magnesium also reduces vulnerability to oxygen-derived free radicals, improves endothelial function and inhibits platelet function, including platelet aggregation and adhesion, which potentially confers upon magnesium physiologic and natural effects similar to adenosine-diphosphate inhibitors such as clopidogrel. However, data regarding the use of magnesium in patients with acute myocardial infarction (AMI) are conflicting. Although some previous relatively small randomized clinical trials demonstrated a remarkable reduction in mortality when intravenous magnesium was administered to relatively high risk AMI patients, two recently published large-scale randomized clinical trials (the Fourth International Study of Infarct Survival [ISIS 4] and Magnesium in Coronaries [MAGIC]) were unable to demonstrate any advantage of intravenous magnesium over placebo. Nevertheless, the theoretical benefits of magnesium supplementation as a cardio-protective agent in CAD patients, promising results from animal and human studies, its relatively low-cost and ease of handling requiring no special expertise, together with its excellent tolerability, gives magnesium a place in treating CAD patients, especially in those at high risk, such as CAD patients with heart failure, the elderly and hospitalized patients with hypomagnesemia. Furthermore, magnesium therapy is indicated in life-threatening ventricular arrhythmias such as torsades de pointes and intractable ventricular tachycardia.

[Thrombolysis in the elderly with acute myocardial infarction. The PRIAMHO study]

INTRODUCTION

In the elderly with acute myocardial infarction the risks and benefits of thrombolytic therapy are not well defined due mainly to the lack of randomized trials. In the present study we examined the clinical profile of the aged treated with thrombolytic agents and the effects of that therapy on 28 day and 1 year mortality.

PATIENTS AND METHODS

We studied 733 patients aged > 75 years (mean: 79.9) admitted to the Coronary Care Unit (CCU) of 24 Spanish hospitals with a confirmed diagnosis of Q-Wave myocardial infarction (MI). On admission, 293 patients were treated with thrombolytics and 440 patients received standard therapy. The difference between the two groups in the clinical profile of MI, treatments administered in CCU, evolutive course and 28 day and 1 year mortality were assessed.

RESULTS

The independent predictors related to the use of thrombolytic therapy were age (OR: 0.93; 95% CI: 0.89-0.97), history of arterial hypertension (OR: 0.85; 95% CI: 0.71-1.01), delay time to admission (OR: 0.998; 95% CI: 0.997-0.999), anterior location of infarct (OR: 1.21; 95% CI: 1.01-1.24) and Killip Class III-IV (OR: 0.79; 95% CI: 0.64-0.97). During the evolution thrombolysis therapy was associated with lower rates of Killip III-IV (p < 0.00001), complete AV block (p = 0.037), intraventricular conduction defects (p = 0.046) and a higher incidence of stroke (p < 0.01). The 28-day mortality was also significantly lower in the group receiving thrombolytics (27 vs 31. 3%; p = 0.035). However, this difference disappeared when the analysis was adjusted with other variables such as age, administration of aspirin and Killip Class III-IV (OR: 1.29; 95% IC: 0.87-1.92).

CONCLUSIONS

The results of this trial suggest that in the elderly with acute myocardial infarction thrombolysis is associated with a less complicated evolutive course and a lower 28-day mortality. However, these findings could be mediated by other covariables such as age, more frequent use of aspirin and a higher number of patients with Killip Class III-IV excluded from the thrombolytic therapy.

Time-trends in thrombolytics: women are catching up

Reports on gender differences in the management of acute coronary syndromes indicate that women do not receive as much active treatment as men. Other conflicting findings have also been published. To investigate whether previously reported gender differences in the treatment of acute myocardial infarction (AMI) still persist, we included all patients admitted to our coronary care unit (CCU) in 1984-1995, and discharged with a diagnosis of AMI, in a retrospective study. A total of 1991 female admissions was compared with 4067 male admissions. The time-span was divided into two-year periods comprising approximately 1000 patients each. During one period, 1988 to 1989, women received significantly less thrombolytic therapy which, however, could reflect that women admitted with AMI were older than men. Analysis of time-trends showed a significant increase in the use of thrombolytic treatment in women and elderly men. In clinical praxis there has been a gender-gap in acute treatment of AMI, but age-dependent or not, this is now no longer apparent.

Thrombolysis in acute myocardial infarction improves prognosis and prolongs life but will increase the prevalence of heart failure in the geriatric population

This paper will review the hypothesis that early complete thrombolytic therapy in acute myocardial infarction reduces mortality and improves prognosis. ACE inhibitors improve remodelling and anti-platelet drugs or interventional procedures prevent reocclusion of the infarct related coronary artery. Most patients are left with significant myocardial damage and this effect is cumulative with subsequent infarction. The average age of death has increased by 10 years in the last three decades, so that many older patients survive. They have survived acute myocardial infarction and we now have a significant population with important heart failure despite good thrombolytic therapy.

Can we provide reperfusion therapy to all unselected patients admitted with acute myocardial infarction?

OBJECTIVES

This study sought to assess the maximal rate of acute Thrombolysis in Myocardial Infarction (TIMI) grade 3 patency that can be achieved in unselected patients.

BACKGROUND

Early and complete (TIMI grade 3 flow) reperfusion is an important therapeutic goal during acute myocardial infarction. However, thrombolysis, although widely used, is often contraindicated or ineffective. The selective use of primary and rescue percutaneous transluminal coronary angioplasty (PTCA) may increase the number of patients receiving reperfusion therapy.

METHODS

A cohort of 500 consecutive unselected patients with acute myocardial infarction were prospectively treated using a patency-oriented scheme: Thrombolysis-eligible patients received thrombolysis (n = 257) and underwent 90-min angiography to detect persistent occlusion for treatment with rescue PTCA. Emergency PTCA (n = 193) was attempted in patients with contraindications to thrombolysis, cardiogenic shock or uncertain diagnosis and in a subset of patients admitted under "ideal conditions." A small group of patients (n = 38) underwent acute angiography without PTCA. Conventional medical therapy was used in 12 patients with contraindications to both thrombolysis and PTCA.

RESULTS

Ninety-eight percent of patients received reperfusion therapy (thrombolysis, PTCA or acute angiography), and angiographically proven early TIMI grade 3 patency was achieved in 78%. Among patients with TIMI grade 3 patency, thrombolysis alone was the strategy used in 37%, emergency PTCA in 40% and rescue PTCA after failed thrombolysis in 15%; spontaneous patency occurred in 8%.

CONCLUSIONS

Reperfusion therapy can be provided to nearly every patient (98%) with acute myocardial infarction. Rescue and direct PTCA provided effective early reperfusion to patients in whom thrombolysis failed or was excluded.

Acute myocardial infarction without thrombolytic therapy: beneficial effects of magnesium sulfate

Only one third of hospitalized patients with acute myocardial infarction (AMI) receive thrombolytic therapy despite its proven benefits on outcomes. Elderly patients, have a greater risk of death during myocardial infarction; however, thrombolytic therapy appears to be less used in these patients, as compared to the general AMI-patients. In order to evaluate the impact of magnesium supplementation in AMI-patients without thrombolytic therapy, 194 patients participated in a prospective, randomized and placebo-controlled study: 96 patients received a 48-hour intravenous magnesium sulfate and 98 isotonic glucose as placebo. Magnesium infusion reduced the incidence of arrhythmias, congestive heart failure and in-hospital-mortality compared with placebo (27 vs. 40%, p = 0.04; 18 vs. 23%, p = 0.27; 4 vs. 17%, p < 0.01, respectively); in the subgroup of elderly patients (> 70 years), the benefit was also obvious (42 vs. 50%; 18 vs. 25%; 9 vs. 23%, p = 0.09, respectively). These data suggest that intravenous magnesium supplementation might be justified in order to reduce myocardial damage and mortality rate in subsets of high-risk patients such the elderly and/or patients not suitable for thrombolysis. Additional trials appear to be indicated to evaluate the potential benefit of magnesium in well defined specific subsets of AMT-patients.

Changing paradigms in thrombolysis in acute myocardial infarction

Acute myocardial infarction occurs when a ruptured coronary artery plaque causes sudden thrombotic occlusion of a coronary artery and cessation of coronary artery blood flow. This paper reviews the underlying coronary pathology in progressive coronary atherosclerosis, mechanisms of plaque rupture and arterial occlusion and the time relationship between coronary occlusion and myocardial necrosis. Reperfusion can be achieved by chemical thrombolysis with different thrombolytic agents. Early lysis is achieved best by prehospital administration, a transtelephonic monitor, a mobile intensive care unit, active general practitioner treatment or by warning the emergency room of impending arrival of a patient. Thrombolytic therapy may be unsuccessful and not achieve Grade III TIMI flow in less than 4 h (or even 2 h) due to inadequate or intermittent perfusion or reocclusion. Adjuvant therapy includes aspirin and platelet receptor antagonists. Bleeding is a constant danger. Direct percutaneous transluminal coronary angioplasty (PTCA) may be as effective or better than chemical thrombolysis. Reperfusion protects the myocardium and salvages viable tissue. It also improves mechanical remodelling of the ventricle. Long-term follow-up has shown that quantum leaps of fresh coronary occlusion causes step-wise progression in patient disability and that further early, prompt reperfusion can salvage myocardium and prevent this inexorable progress of the disease.

The rationale of magnesium as alternative therapy for patients with acute myocardial infarction without thrombolytic therapy

Only one third of hospitalized patients with acute myocardial infarction receive thrombolytic therapy despite its proven benefits on outcomes. Elderly patients, for example, have a greater risk of death after myocardial infarction, but studies demonstrate that thrombolytic therapy is less likely to be used in older patients. Intravenous magnesium supplementation, both theoretically and experimentally, has been demonstrated to decrease myocardial damage and reduce the mortality rate in subsets of patients, including the elderly and/or patients not suitable for thrombolysis, if it is administered before reperfusion occurs. The aim of this study is to review the rationale for patients with acute myocardial infarction without thrombolytic therapy.

Prospective evaluation of eligibility for thrombolytic therapy in acute myocardial infarction

OBJECTIVES

To determine the proportion of patients presenting with acute myocardial infarction who are eligible for thrombolytic therapy.

DESIGN

Cohort follow up study.

SETTING

The four coronary care units in Auckland, New Zealand.

SUBJECTS

All 3014 patients presenting to the units with suspected myocardial infarction in 1993.

MAIN OUTCOME MEASURES

Eligibility for reperfusion with thrombolytic therapy (presentation within 12 hours of the onset of ischaemic chest pain with ST elevation > or = 2 mm in leads V1-V3, ST elevation > or = 1 mm in any other two contiguous leads, or new left bundle branch block); proportions of (a) patients eligible for reperfusion and (b) patients with contraindications to thrombolysis; death (including causes); definite myocardial infarction.

RESULTS

948 patients had definite myocardial infarction, 124 probable myocardial infarction, and nine ST elevation but no infarction; 1274 patients had unstable angina and 659 chest pain of other causes. Of patients with definite or probable myocardial infarction, 576 (53.3%) were eligible for reperfusion, 39 had definite contraindications to thrombolysis (risk of bleeding). Hence 49.7% of patients (537/1081) were eligible for thrombolysis and 43.5% (470) received this treatment. Hospital mortality among patients eligible for reperfusion was 11.7% (55/470 cases) among those who received thrombolysis and 17.0% (18/106) among those who did not.

CONCLUSIONS

On current criteria about half of patients admitted to coronary care units with definite or probable myocardial infarction are eligible for thrombolytic therapy. Few eligible patients have definite contraindications to thrombolytic therapy. Mortality for all community admissions for myocardial infarction remains high.

Primary angioplasty and thrombolysis for acute myocardial infarction: an evidence summary

Coronary angioplasty is being increasingly used as the primary treatment for patients with acute myocardial infarction, but controversy remains over its potential adoption in preference to thrombolysis as standard care. This report summarizes the published evidence on health outcomes after primary angioplasty compared with thrombolysis or no intervention for patients with acute myocardial infarction. The data tables presented provide the scientific groundwork to assist physicians and other policy-makers in deciding which interventions to provide for broad populations of patients.

Acute myocardial infarction treatments in 58 Italian hospitals: a drug utilization survey

OBJECTIVES

To provide an updated and comprehensive profile of therapeutic practice in the management of acute myocardial infarction (AMI) in a sample of Italian hospitals, and to test the possible role of a network of hospital pharmacists in providing drug utilization data.

DESIGN

Prospective drug utilization survey. Participating pharmacists collected information on patients consecutively admitted to the hospital with a suspected AMI. The form reproduced those adopted in the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto miocardico trials.

SETTING

Fifty-eight general hospitals in Italy belonging to the National Health Service, 6 of which are teaching hospitals. Thirty-four hospitals recruited patients from a coronary care unit, 10 from intensive monitoring beds in cardiology wards, and 14 from an intensive care unit.

PARTICIPANTS

The study population consisted of patients consecutively admitted with a suspected AMI from May 31 through July 5, 1993.

MAIN OUTCOME MEASURES

The management of AMI in terms of the use of drugs and nonpharmacologic treatments is described.

RESULTS

Of the 676 patients recruited for the study, 47.8% received thrombolytic therapy; alteplase was the preferred agent (55.4% of treated patients). The use of thrombolytic therapy varied significantly according to different demographic and clinical parameters such as age, sex, delay from the onset of symptoms to admission, and Killip scale class. During the first day of hospitalization 63.9% of patients received aspirin, 83.3% received nitrates, 24.8% received beta-blockers, and 77.1% received heparin therapy.

CONCLUSIONS

Thrombolytic therapy was prescribed in a higher percentage of patients than is reported in the US, but lower than that reported in large trials. That a low percentage of patients who experienced a long delay between the onset of symptoms and admission as well as elderly patients received thrombolytic therapy reflects the lower expectations of clinicians for these subgroups of patients. A low proportion of patients received aspirin therapy. This study showed that in Italy an institutional network of hospital pharmacists could be interested observers of therapeutic practice, but further training is needed before high-quality data can be collected.

Early intravenous thrombolysis in acute myocardial infarction: the Jerusalem experience

Myocardial damage in acute myocardial infarction is a time-dependent process. We examined the influence of very early thrombolytic therapy, comparing prehospital to hospital administration, in a consecutive group of patients with myocardial infarction on mortality, complications and the preservation of left ventricular function. Seven hundred sixty patients received early thrombolytic therapy: 114 at home (time delay to treatment 1.4 +/- 0.8 h) and 646 in hospital (2.1 +/- 1.0 h). Sixteen patients died in hospital and significant hemorrhage occurred in 15 (including three patients with hemorrhagic stroke). There was no difference between groups in hospital mortality or rate of complications. The duration of ischemia was shorter in patients with prehospital therapy (pain duration: 3.3 +/- 2.1 vs. 4.0 +/- 2.2; P < 0.05, and time to recovery of the ST segment in the electrocardiogram: 4.3 +/- 3.3 vs. 6.6 +/- 6.3; P < 0.002). Peak plasma creatine kinase was earlier in patients with prehospital therapy (11.2 +/- 5.0 vs. 13.0 +/- 5.8; P < 0.002), although there was no difference between groups in the absolute peak plasma level. Left ventricular function was assessed by contrast ventriculography 1 week after admission (616 patients). Ventricular function was better in patients with prehospital therapy: (ejection fraction of 58 +/- 13% vs. 54 +/- 15%; P < 0.05 and a left ventricular dysfunction index of 534 +/- 515 vs. 691 +/- 519 units; P < 0.05). We conclude that prehospital thrombolytic therapy is feasible and safe. Reperfusion is achieved earlier and more myocardium can be salvaged using this strategy without increasing the rate of complications.

Magnesium therapy in acute myocardial infarction when patients are not candidates for thrombolytic therapy

Thrombolytic therapy reduces in-hospital mortality. However, 70% to 80% of patients do not receive thrombolysis and their in-hospital mortality is high. During the last decade some clinical trials demonstrated that magnesium sulfate reduced in-hospital mortality. The aim of this study was to evaluate the effects of magnesium sulfate in patients with acute myocardial infarction (AMI) who were considered unsuitable for thrombolytic therapy. Intravenous magnesium sulfate was evaluated in 194 patients with AMI ineligible for thrombolytic therapy in a randomized, double-blind, placebo-controlled study. Group I consisted of 96 patients who received 48-hour intravenous magnesium. Group II consisted of 98 patients who received isotonic glucose as a placebo. Magnesium reduced the incidence of arrhythmias, congestive heart failure, and conduction disturbances compared with placebo (27% vs 40%, p = 0.04; 18% vs 23%, p = 0.27; 10% vs 15%, p = 0.21, respectively). Left ventricular ejection fraction 72 hours and 1 to 2 months after admission was higher in patients who received magnesium sulfate than in those taking placebo (49% vs 43% and 52% vs 45%; p = 0.01, respectively). In-hospital mortality was significantly reduced in patients receiving magnesium sulfate than in those receiving placebo (4% vs 17%; p < 0.01), and also in the subgroup of elderly patients (> 70 years) (9% vs 23%; p = 0.09). In conclusion, magnesium sulfate should be considered as an alternative therapy to thrombolysis in patients with AMI.

Influence of gender in the therapeutic management of patients with acute myocardial infarction in Israel. The Israeli Thrombolytic Survey Group

A national study was performed in early 1992 in the 25 operating coronary care units in Israel, which enabled the assessment of whether the therapeutic management of patients with acute myocardial infarction was affected by patient gender. During a 2-month period, 1,014 consecutive patients with acute myocardial infarction were hospitalized. Thrombolytic therapy was given to 47% of men (362 of 769), and 43% of women (106 of 245) (p = NS). After adjustment for age, no gender differences in the administration of thrombolytic therapy were noted (odds ratio 0.95; 95% confidence interval 0.73-1.23). Coronary angiography was more frequently performed in men (22%) than in women (16%) (p < 0.05). However, no gender differences in the use of angioplasty or coronary bypass surgery performed during the index hospitalization were found (10% in men, and 8% in women). The main reasons for ineligibility for thrombolytic therapy were: late hospital arrival, absence of qualifying ST-T changes on admission electrocardiogram, and contraindications to thrombolytic therapy. Hospital death was significantly lower in patients receiving thrombolytic therapy (37 of 456; 8%) than in those excluded from thrombolysis (70 of 540;13%) (p < 0.01). This difference was significant for men, but not for women. The 1-year postdischarge mortality was 4% in patients treated compared with 12% in those ineligible for thrombolysis (p < 0.01). This significant difference persisted among men and women.

Primary coronary angioplasty for acute myocardial infarction with contraindication to thrombolysis

Patients with acute myocardial infarction (AMI) and contraindication to thrombolysis have a high mortality and morbidity with conventional medical treatment. Among 226 consecutive patients hospitalized within 6 hours of the onset of Q-wave AMI, 45 (20%) had contraindications to thrombolysis. All were treated by emergent primary angioplasty. Mean age of the 45 patients was 60 +/- 11 years and 8 (18%) were > or = 70 years old; 17 (38%) had multivessel disease and 5 (11%) presented with cardiogenic shock. Successful angioplasty was achieved in 42 of the 45 patients (93%) 52 +/- 27 minutes after admission and 238 +/- 100 minutes after the onset of pain. Overall in-hospital mortality was 9% (4 of 45). Neither major bleeding nor stroke occurred. There was 1 case of early symptomatic reocclusion, treated with emergent repeat angioplasty without reinfarction. Predischarge angiography in 33 patients showed only 1 silent reocclusion (3%). Ejection fraction at discharge was 46 +/- 13%. Repeat catheterization at 6 months in 19 patients showed 4 restenoses (21%) and 4 reocclusions (21%) of the infarct-related artery. There were 3 late deaths (2 noncardiac), which gave survival rates of 87 and 85% at 1 and 3 years, respectively, and event-free survival rates of 71 and 69% including in-hospital deaths. There were no cases of late reinfarction. Consequently, in this series, primary coronary angioplasty proved safe and highly effective in rapidly restoring sustained infarct-vessel patency during AMI, and led to a greater improvement in early and late outcomes than that reported in the literature for medically treated subjects in this high-risk subset for which thrombolytic therapy is contraindicated.