Translation of clinical trials into clinical practice.

The results of well-conducted clinical trials should be translated into practice but there is good evidence that this is not happening. There are a number of reasons for this - ignorance of doctors and patients, uncertainty as to the applicability of trials to individual patients, indolence and inefficiency on the part of practitioners, and financial considerations. More attention needs to be paid to correct all these factors.

Diltiazem in acute myocardial infarction treated with thrombolytic agents: a randomised placebo-controlled trial. Incomplete Infarction Trial of European Research Collaborators Evaluating Prognosis post-Thrombolysis (INTERCEPT)

BACKGROUND: Diltiazem reduces non-fatal reinfarction and refractory ischaemia after non-Q-wave myocardial infarction, an acute coronary syndrome similar to the incomplete infarction that occurs after successful reperfusion. We postulated that this agent would reduce cardiac events in patients after acute myocardial infarction treated initially with thrombolytic agents-a clinical application previously unexplored with heart-rate-lowering calcium antagonists. METHODS: A prospective, randomised, double-blind, sequential trial was done in 874 patients with acute myocardial infarction, but without congestive heart failure, who first received thrombolytic agents. Patients received either 300 mg oral diltiazem once daily, or placebo, initiated within 36-96 h of infarct onset, and given for up to 6 months. The trial primary endpoint was the cumulative first event rate of cardiac death, non-fatal reinfarction, or refractory ischaemia. Additional prespecified endpoints included several composites of non-fatal cardiac events (non-fatal reinfarction combined with refractory ischaemia, all recurrent ischaemia, or the need for myocardial revascularisation). The diagnosis of ischaemia, whether refractory or recurrent, and the need for myocardial revascularisation, was always based on objective electrocardiographical evidence of ischaemia, either at rest or on exertion. RESULTS: For the trial primary endpoint, 131 events occurred in the 444 placebo patients and 97 events in the 430 diltiazem patients (hazard ratio 0.79; 95% CI, 0.61-1.02; p=0.07). For non-fatal cardiac events, diltiazem treatment was associated with a relative decrease (0.76; 0.58-1.00) in the combined event rate of non-fatal reinfarction and refractory ischaemia. There was a similar decrease in the composite non-fatal endpoints of non-fatal reinfarction combined with all recurrent ischaemia (0.80; 0.64-1.00) and non-fatal reinfarction combined with the need for myocardial revascularisation (0.67; 0.46-0.96). The need for myocardial revascularisation alone was significantly reduced by 42% (0.61; 0.39-0.96). No major safety issues were encountered. CONCLUSIONS: Diltiazem did not reduce the cumulative occurrence of cardiac death, non-fatal reinfarction, or refractory ischaemia during a 6-month follow-up, but did reduce all composite endpoints of non-fatal cardiac events, especially the need for myocardial revascularisation.

Depressed heart rate variability identifies postinfarction patients who might benefit from prophylactic treatment with amiodarone: a substudy of EMIAT (The European Myocardial Infarct Amiodarone Trial).

OBJECTIVES: This substudy tested a prospective hypothesis that European Myocardial Infarct Amiodarone Trial (EMIAT) patients with depressed heart rate variability (HRV) benefit from amiodarone treatment. BACKGROUND: The EMIAT randomized 1,486 survivors of acute myocardial infarction (MI) aged < or =75 years with left ventricular ejection fraction (LVEF) < or =40% to amiodarone or placebo. Despite a reduction of arrhythmic mortality on amiodarone, all-cause mortality was not changed. METHODS: Heart rate variability was assessed from prerandomization 24-h Holter tapes in 1,216 patients (606 on amiodarone). Two definitions of depressed HRV were used: standard deviation of normal to normal intervals (SDNN) < or =50 ms and HRV index < or =20 units. The survival of patients with depressed HRV was compared in the placebo and amiodarone arms. A retrospective analysis investigated the prospective dichotomy limits. All tests were repeated in five subpopulations: patients with first MI, patients on beta-adrenergic blocking agents, patients with LVEF < or =30%, patients with Holter arrhythmia and patients with baseline heart rate > or =75 beats/min. RESULTS: Centralized Holter processing produced artificially high SDNN but accurate HRV index values. Heart rate variability index was < or =20 U in 363 (29.9%) patients (183 on amiodarone) with all-cause mortality 22.8% on placebo and 17.5% on amiodarone (23.2% reduction, p = 0.24) and cardiac arrhythmic mortality 12.8% on placebo and 4.4% on amiodarone (66% reduction, p = 0.0054). Among patients with prospectively defined depressed HRV, the largest reduction of all-cause mortality was in patients with first MI (placebo 17.9%, amiodarone 10.3%, 42.5% reduction, p = 0.079) and in patients with heart rate < or =75 beats/min (placebo 29.0%, amiodarone 19.3%, 33.7% reduction, p = 0.075). Among patients with first MI and depressed HRV, amiodarone treatment was an independent predictor of survival in a multivariate Cox analysis. The retrospective analysis found a larger reduction of mortality on amiodarone in 313 (25.7%) patients with HRV index < or =19 U: 23.9% on placebo and 17.1% on amiodarone (28.4% reduction, p = 0.15). This was more expressed in patients with first MI: 49.4% mortality reduction on amiodarone (p = 0.046), on beta-blockers: 69.0% reduction (p = 0.047) and with heart rate > or =75 beats/min: 37.9% reduction (p = 0.054). CONCLUSION: Measurement of HRV in a large set of centrally processed Holter recordings is feasible with robust methods of assessment. Patients with LVEF < or =40% and depressed HRV benefit from prophylactic antiarrhythmic treatment with amiodarone. However, this finding needs confirmation in an independent data set before clinical practice is changed.

Effect of mivazerol on perioperative cardiac complications during non-cardiac surgery in patients with coronary heart disease: the European Mivazerol Trial (EMIT).

BACKGROUND: Mivazerol is a drug with alpha2-agonist properties that reduces post-ganglionic noradrenaline availability and spinal efferent sympathetic output. METHODS: A double-blind randomized placebo-controlled trial was conducted in 61 European centers during a 2.5-yr period on 2,854 patients: 1,897 with coronary heart disease and 957 patients without overt coronary heart disease but classified as at high risk for it. The present analysis was restricted to those patients with previous known coronary heart disease of whom 48% had vascular surgery, 32% non-vascular thoracic or abdominal surgery, and 20% orthopedic surgery. Mivazerol or placebo were given intravenously from the induction of anesthesia for up to 72 h. RESULTS: In the 1,897 patients with established coronary heart disease, mivazerol did not reduce the primary endpoint--the combination of myocardial infarction or death--or all-cause deaths significantly. A preplanned subgroup analysis of 904 patients with known coronary heart disease undergoing vascular surgery showed that there were fewer primary endpoints in those receiving mivazerol (risk ratio [RR], 0.67; 95% CL, 0.45-0.98; P = 0.037) and fewer cardiac deaths (6 of 454 vs. 18 of 450: RR, 0.33; 95% confidence limits, 0.13-0.82; P = 0.017). The all-cause death rate was also decreased (RR, 0.41; 95% CL, 0.18-0.91; P = 0.024), although there was no significant reduction in myocardial infarction. CONCLUSION: The alpha2-adrenergic agonist, mivazerol, did not alter the rates of myocardial infarction or cardiac death in patients with known coronary heart disease undergoing noncardiac surgery. However, it may have protected patients undergoing vascular surgery from further coronary events, and a specific study of such patients is now indicated.

Amiodarone interaction with beta-blockers: analysis of the merged EMIAT (European Myocardial Infarct Amiodarone Trial) and CAMIAT (Canadian Amiodarone Myocardial Infarction Trial) databases. The EMIAT and CAMIAT Investigators.

BACKGROUND: Investigations with in vitro and animal models suggest an interaction between amiodarone and beta-blockers. The objective of this work was to explore if an interaction with beta-blocker treatment plays a role in the decrease of cardiac arrhythmic deaths with amiodarone in patients recovered from an acute myocardial infarction. METHODS AND RESULTS: A pooled database from 2 similar randomized clinical trials, the European Amiodarone Myocardial Infarction Trial (EMIAT) and the Canadian Amiodarone Myocardial Infarction Trial (CAMIAT), was used. Four groups of post-myocardial infarction patients were defined: beta-blockers and amiodarone used, beta-blockers used alone, amiodarone used alone, and neither used. All analyses were done on an intention-to-treat basis. Unadjusted and adjusted relative risks for all-cause mortality, cardiac death, arrhythmic cardiac death, nonarrhythmic cardiac death, arrhythmic death, or resuscitated cardiac arrest were lower for patients receiving beta-blockers and amiodarone than for those without beta-blockers, with or without amiodarone. The interaction was statistically significant for cardiac death and arrhythmic death or resuscitated cardiac arrest (P=0.05 and 0.03, respectively). Findings were consistent across subgroups. CONCLUSIONS: These findings are based on a post hoc analysis. However, they confirm prior results from in vitro and animal experiments suggesting an interaction between beta-blockers and amiodarone. In practice, not only is the adjunct of amiodarone to beta-blockers not hazardous, but beta-blocker therapy should be continued if possible in patients in whom amiodarone is indicated.

The agonising negative trend in monitoring of clinical trials.

Randomised clinical trials are undertaken in the hope of showing positive benefits of a new treatment, but on occasion quite the opposite trend can occur, If the interim data suggest possible negative (harmful) effects of a new treatment. The handling of such emerging negative trends is among the most complicated and ethically challenging scenarios in monitoring clinical trials through repeated interim analyses. Statistical methods are helpful to detect the point of no likely beneficial effect, and the point that separates neutral results from harmful results. However, in practice the decision whether (and exactly when) to stop such a trial involves a complex of other issues that depends on the context of the disease, the treatment being assessed, and the current practice of medicine. Owing to this complexity, an Independent Data and Safety Monitoring Board (DSMB) is best suited to deal with such a situation. Prediction of whether a negative trend will emerge in any trial is not possible. Negative trends were not anticipated in the cardiovascular trials and the trials of lung-cancer prevention described here. In the light of these experiences, all trials and their DSMBs should consider ahead of time the possibility of unexpectedly harmful results, and should document appropriately the statistical guidelines and the decision-making process required to cope with such undesirable events.

Identification of post acute myocardial infarction patients with potential benefit from prophylactic treatment with amiodarone. A substudy of EMIAT (the European Myocardial Infarct Amiodarone Trial).

AIMS: To perform a retrospective analysis of subgroups of patients enrolled into the European Myocardial Infarct Amiodarone Trial (EMIAT) in order to identify patients who might benefit from prophylactic amiodarone treatment and patients in whom amiodarone might be harmful. METHODS: Baseline characteristics of the 1486 patients enrolled in EMIAT were used to investigate the all-cause mortality effect of amiodarone (intention-to-treat) in patients with a left ventricular ejection fraction 30-40% and < 30%, in patients with and without arrhythmia signs on Holter recordings, in patients with high and low baseline resting heart rate, in patients on and off beta-blocker treatment, and in a combination of these groups. RESULTS: A univariate analysis suggested that all-cause mortality is reduced on amiodarone in patients with an ejection fraction < 30%, with arrhythmia on the initial Holter, on beta-blocker treatment, and with an increased initial heart rate. A trend towards an increase of all-cause mortality was noted in patients with an ejection fraction 30-40%, without arrhythmia on Holter, off beta-blockers, and with a low baseline heart rate. A multivariate analysis suggested that the univariate observations are mutually additive. CONCLUSIONS: The study might serve as a basis for future prospective trials where amiodarone could be tested in patients with a recent myocardial infarction, having a reduced left ventricular ejection fraction, a high initial heart rate, and taking beta-blockers.

Randomised trial of effect of amiodarone on mortality in patients with left-ventricular dysfunction after recent myocardial infarction: EMIAT. European Myocardial Infarct Amiodarone Trial Investigators.

BACKGROUND: Ventricular arrhythmias are a major cause of death after myocardial infarction, especially in patients with poor left-ventricular function. Previous attempts to identify and suppress arrhythmias with various antiarrhythmic drugs failed to reduce or actually increase mortality. Amiodarone is a powerful antiarrhythmic drug with several potentially beneficial actions, and has shown benefit in several small-scale studies. We postulated that this drug might reduce mortality in patients at high risk of death after myocardial infarction because of impaired ventricular function, irrespective of whether they had ventricular arrhythmias. METHODS: The European Myocardial Infarct Amiodarone Trial (EMIAT) was a randomised double-blind placebo-controlled trial to assess whether amiodarone reduced all-cause mortality (primary endpoint) and cardiac mortality and arrhythmic death (secondary endpoints) in survivors of myocardial infarction with a left-ventricular ejection fraction (LVEF) of 40% or less. Intention-to-treat and on-treatment analyses were done. FINDINGS: EMIAT enrolled 1486 patients (743 in the amiodarone group, 743 in the placebo group). Median follow-up was 21 months. All-cause mortality (103 deaths in the amiodarone group, 102 in the placebo group) and cardiac mortality did not differ between the two groups. However, in the amiodarone group, there was a 35% risk reduction (95% CI 0-58, p = 0.05) in arrhythmic deaths. INTERPRETATION: Our findings do not support the systematic prophylactic use of amiodarone in all patients with depressed left-ventricular function after myocardial infarction. However, the lack of proarrhythmia and the reduction in arrhythmic death support the use of amiodarone in patients for whom antiarrhythmic therapy is indicated.

A comparison of aspirin and anticoagulation following thrombolysis for myocardial infarction (the AFTER study): a multicentre unblinded randomised clinical trial.

OBJECTIVE: To compare aspirin with anticoagulation with regard to risk of cardiac death and reinfarction in patients who received anistreplase thrombolysis for myocardial infarction. DESIGN: A multicentre unblinded randomised clinical trial. SETTING: 38 hospitals in six countries. SUBJECTS: 1036 patients who had been treated with anistreplase for myocardial infarction were randomly assigned to either aspirin (150 mg daily) or anticoagulation (intravenous heparin followed by warfarin or other oral anticoagulant). The trial was stopped earlier than originally intended because of the slowing rate of recruitment. MAIN OUTCOME MEASURE: Cardiac death or recurrent myocardial infarction at 30 days. RESULTS: After 30 days cardiac death or reinfarction, occurred in 11.0% (57/517) of the patients treated with anticoagulation and 11.2% (58/519) of the patients treated with aspirin (odds ratio 1.02, 95% confidence interval 0.69 to 1.50, P = 0.92). Corresponding findings at three months were 13.2% (68/517) and 12.1% (63/519) (0.91, 0.63 to 1.32, P = 0.67). Patients receiving anticoagulation were more likely than patients receiving aspirin to have had severe bleeding or a stroke by three months (3.9% v 1.7% (0.44, 0.20 to 0.97, P = 0.04)). CONCLUSION: No evidence of a difference in the incidence of cardiac events was found between the two treatment groups, though the trial is too small to claim treatment equivalence confidently. A higher incidence of severe bleeding events and strokes was detected in the group receiving anticoagulation, suggesting that aspirin may be the drug of choice for most patients in this context.

Time as a factor in thrombolytic therapy.

Animal studies first demonstrated the importance of early reperfusion in limiting the size of eventual infarction. This has been confirmed by human studies in which the early patency of the infarct-related artery is correlated with prognosis. Large randomised clinical trials suggested a graded effect, with a particularly great benefit if therapy was administered during the first hour after the onset of symptoms, and a progressive diminution in the effect thereafter, up to 12 h, and perhaps beyond. These studies did not, however, randomise patients to earlier or later treatment so the comparisons of different time intervals were not entirely valid. Five mortality trials have now randomised patients to early or later treatment and have demonstrated a significant benefit if more than 1 h is gained thereby. These trials were individually not large enough to establish the degree of gain from earlier treatment, but pooling their results suggests that gaining about 1 h will reduce mortality by about 17%.

Treatment for survivors of acute myocardial infarction: what have we learned from large intervention trials?

The current treatment of survivors of acute myocardial infarction is now largely based on sound scientific principles, supported by the results of large and well-designed clinical trials. These have demonstrated that aspirin, anticoagulants, beta-blockers, angiotensin converting enzyme inhibitors, and lipid-lowering agents reduce mortality and reinfarction in selected groups of patients. It remains uncertain whether these different treatments are additive and whether there are beneficial or undesirable interactions. In addition to informing us about the effectiveness or otherwise of these and other drugs, we have learned much about the conduct, analysis, and limitations of clinical trials in this context. The selection of patients for the various treatments is a matter of opinion because the results of the trials are open to a variety of interpretations. In assessing trials, one must be sure that they have been conducted on the intention to treat principle and that surrogate and composite end points have not been inappropriately used. In applying the results of trials to one's own practice, one must take into account the problems of extrapolation and subgroup analysis.