David F. Kong

Perioperative Bridging Anticoagulation in Patients With Atrial Fibrillation

BACKGROUND It is uncertain whether bridging anticoagulation is necessary for patients with atrial fibrillation who need an interruption in warfarin treatment for an elective operation or other elective invasive procedure. We hypothesized that forgoing bridging anticoagulation would be noninferior to bridging with low-molecular-weight heparin for the prevention of perioperative arterial thromboembolism and would be superior to bridging with respect to major bleeding. METHODS We performed a randomized, double-blind, placebo-controlled trial in which, after perioperative interruption of warfarin therapy, patients were randomly assigned to receive bridging anticoagulation therapy with low-molecular-weight heparin (100 IU of dalteparin per kilogram of body weight) or matching placebo administered subcutaneously twice daily, from 3 days before the procedure until 24 hours before the procedure and then for 5 to 10 days after the procedure. Warfarin treatment was stopped 5 days before the procedure and was resumed within 24 hours after the procedure. Follow-up of patients continued for 30 days after the procedure. The primary outcomes were arterial thromboembolism (stroke, systemic embolism, or transient ischemic attack) and major bleeding. RESULTS In total, 1884 patients were enrolled, with 950 assigned to receive no bridging therapy and 934 assigned to receive bridging therapy. The incidence of arterial thromboembolism was 0.4% in the no-bridging group and 0.3% in the bridging group (risk difference, 0.1 percentage points; 95% confidence interval [CI], -0.6 to 0.8; P=0.01 for noninferiority). The incidence of major bleeding was 1.3% in the no-bridging group and 3.2% in the bridging group (relative risk, 0.41; 95% CI, 0.20 to 0.78; P=0.005 for superiority). CONCLUSIONS In patients with atrial fibrillation who had warfarin treatment interrupted for an elective operation or other elective invasive procedure, forgoing bridging anticoagulation was noninferior to perioperative bridging with low-molecular-weight heparin for the prevention of arterial thromboembolism and decreased the risk of major bleeding. (Funded by the National Heart, Lung, and Blood Institute of the National Institutes of Health; BRIDGE ClinicalTrials.gov number, NCT00786474.).

Clinical Outcomes of Therapeutic Agents That Block the Platelet Glycoprotein IIb/IIIa Integrin in Ischemic Heart Disease

BACKGROUND Several platelet glycoprotein (GP) IIb/IIIa receptor antagonists have been evaluated in clinical trials. We conducted a systematic overview (meta-analysis) to assess the effect of these compounds on death, myocardial infarction (MI), and revascularization. METHODS AND RESULTS ORs were calculated for 16 randomized, controlled trials of GP IIb/IIIa inhibitors. An empirical Bayesian random-effects model combined the outcomes of 32 135 patients. There was a significant mortality reduction by GP IIb/IIIa inhibitors at 48 to 96 hours, with an OR of 0.70 (95% CI, 0. 51 to 0.96; P<0.03), equivalent to a reduction of 1 death per 1000 patients treated. Mortality benefits at 30 days (OR, 0.87; 95% CI, 0. 74 to 1.02; P=0.08) and 6 months (OR, 0.97; 95% CI, 0.86 to 1.10; P=0.67) were not statistically significant. For the combined end point of death or MI, there was a highly significant (P<0.001) benefit for GP IIb/IIIa inhibitors at each time point. The 30-day OR was 0.76 (95% CI, 0.66 to 0.87), or 20 fewer events per 1000 patients treated. For the composite end point of death, MI, or revascularization, there was also a highly significant (P<0.001) benefit for GP IIb/IIIa inhibitors. At 30 days, the OR was 0.77 (95% CI, 0.68 to 0.86), or 30 fewer events per 1000 patients treated. The risk differences for death, death or MI, and composite outcomes were similar at 6 months, indicating a sustained absolute improvement. Similar benefit was seen when trials were subgrouped by therapeutic indication (percutaneous intervention versus acute coronary syndromes). CONCLUSIONS Application of this new therapeutic class to clinical practice promises substantial benefit for both indications.

Coronary Artery Pattern and Outcome of Arterial Switch Operation for Transposition of the Great Arteries A Meta-Analysis

Background—Prior studies of coronary pattern and outcome after arterial switch operation (ASO) for transposition of the great arteries (TGA) have been hindered by limited statistical power. This meta-analysis assesses the effect of coronary anatomy on post-ASO mortality, both overall and adjusted for time. Methods and Results—A literature search revealed 9 independent series that reported post-ASO mortality by coronary pattern in a total of 1942 patients. Odds ratios comparing all-cause mortality in patients with usual versus variant coronary patterns were calculated and combined by use of an empirical Bayesian model. Single coronary patterns, both of which loop around the great vessels, were associated with significant mortality (OR 2.9, 95% CI 1.3 to 6.8), whereas looping patterns that arose from 2 separate ostia were not (OR 1.2, 95% CI 0.8 to 1.9). This latter group includes patients with the most common variant, circumflex from right coronary artery. Patients with an intramural coronary artery had the greatest mortality (OR 6.5, 95% CI 2.9 to 14.2). Overall, patients with any variant coronary pattern had nearly twice the mortality seen in those with the usual pattern (OR 1.7, 95% CI 1.3 to 2.4). Single ostium patterns and intramural coronary arteries remained associated with significant added mortality after adjustment for time-trend effects. Conclusions—Over the past 2 decades, patients with common coronary variants have undergone ASO without added mortality compared with those with the usual coronary pattern. Those with intramural or single coronary arteries have significant added mortality that has persisted over time.

Comparative Efficacy of Dronedarone and Amiodarone for the Maintenance of Sinus Rhythm in Patients With Atrial Fibrillation

OBJECTIVES We sought to compare the efficacy and safety of dronedarone versus amiodarone for the prevention of recurrent atrial fibrillation (AF). BACKGROUND Dronedarone is a noniodinated amiodarone congener developed to maintain sinus rhythm. Few data are available to directly compare the efficacy and safety of dronedarone versus amiodarone. METHODS We conducted a systematic overview of all randomized controlled trials in which the authors evaluated dronedarone or amiodarone for the prevention of AF. The effect of amiodarone versus dronedarone was summarized by the use of indirect comparison meta-analysis and normal logistic meta-regression models. RESULTS We identified 4 placebo-controlled trials of dronedarone, 4 placebo-controlled trials of amiodarone, and 1 trial of dronedarone versus amiodarone. By using random-effects modeling, we found that there was a significant estimated reduction in recurrent AF with amiodarone versus placebo (odds ratio [OR]: 0.12; 95% confidence interval [CI]: 0.08 to 0.19) but not dronedarone versus placebo (OR: 0.79; 95% CI: 0.33 to 1.87). A normal logistic regression model incorporating all trial evidence found amiodarone superior to dronedarone (OR: 0.49; 95% CI: 0.37 to 0.63; p < 0.001) for the prevention of recurrent AF. In contrast, these models also found a trend toward greater all-cause mortality (OR: 1.61; 95% CI: 0.97 to 2.68; p = 0.066) and greater overall adverse events requiring drug discontinuation with amiodarone versus dronedarone (OR: 1.81; 95% CI: 1.33 to 2.46; p < 0.001). CONCLUSIONS Dronedarone is less effective than amiodarone for the maintenance of sinus rhythm, but has fewer adverse effects. For every 1,000 patients treated with dronedarone instead of amiodarone, we estimate approximately 228 more recurrences of AF in exchange for 9.6 fewer deaths and 62 fewer adverse events requiring discontinuation of drug.

Statistical Methods for Comparison to Placebo in Active-Control Trials

There has been a proliferation of active-control clinical trials comparing experimental therapies with standard ones (active control). In such cases, one often wants to know how the experimental therapy would have performed if it had been compared directly to placebo. This comparison requires 1. The observed effectiveness of experimental treatment compared to the active-control, and 2. The estimated effectiveness of the active-control therapy versus placebo (often obtained from a meta-analysis). If these two estimates apply to a common subpopulation, then two additional measures can be derived: 3. The estimated effectiveness of the experimental therapy relative to placebo, and 4. The estimated fraction of effect preserved by the experimental therapy. All four of these estimates can be described by point estimates, confidence intervals, and associated p-values. Our calculations have shown that if we use the conventional methods to compute the fraction of effect preserved based on the addition of confidence intervals, we dramatically increase the sample size required for studies of the experimental treatment versus standard therapy. As newer therapies become the standard therapies, we can expect that we will have a sequence of comparisons required to estimate the effect of the newest therapy relative to placebo, and this can be estimated using a generalization of the methodology just described. This comparison addresses the issue of “drift” (the risk that a series of active-control trials might push the general therapy in the wrong direction by accepting therapies that are worse than previously approved therapy). The problem of combining evidence from studies with several different treatment arms is also generalization of the methodology described previously. The solution to the problem requires that we assume that all of the odds ratios between the various treatments remain constant (1). We illustrate the method with an example from data on thrombolytics.

Clinical Effectiveness of Coronary Stents in Elderly Persons: Results From 262,700 Medicare Patients in the American College of Cardiology―National Cardiovascular Data Registry

OBJECTIVES The aim of this study was to compare outcomes in older individuals receiving drug-eluting stents (DES) and bare-metal stents (BMS). BACKGROUND Comparative effectiveness of DES relative to BMS remains unclear. METHODS Outcomes were evaluated in 262,700 patients from 650 National Cardiovascular Data Registry sites during 2004 to 2006 with procedural registry data linked to Medicare claims for follow-up. Outcomes including death, myocardial infarction (MI), revascularization, major bleeding, stroke, death or MI, death or MI or revascularization, and death or MI or stroke were compared with estimated cumulative incidence rates with inverse probability weighted estimators and Cox proportional hazards ratios. RESULTS The DES were implanted in 217,675 patients and BMS were implanted in 45,025. At 30 months, DES patients had lower unadjusted rates of death (12.9% vs. 17.9%), MI (7.3 of 100 patients vs. 10.0 of 100 patients), and revascularization (23.0 of 100 patients vs. 24.5 of 100 patients) with no difference in stroke or bleeding. After adjustment, DES patients had lower rates of death (13.5% vs. 16.5%, hazard ratio [HR]: 0.75, 95% confidence interval [CI]: 0.72 to 0.79, p < 0.001) and MI (7.5 of 100 patients vs. 8.9 of 100 patients, HR: 0.77, 95% CI: 0.72 to 0.81, p < 0.001), with minimal difference in revascularization (23.5 of 100 patients vs. 23.4 of 100 patients; HR: 0.91, 95% CI: 0.87 to 0.96), stroke (3.1 of 100 patients vs. 2.7 of 100 patients, HR: 0.97, 95% CI: 0.88 to 1.07), or bleeding (3.4 of 100 patients vs. 3.6 of 100 patients, HR: 0.91, 95% CI: 0.84 to 1.00). The DES survival benefit was observed in all subgroups analyzed and persisted throughout 30 months of follow-up. CONCLUSIONS In this largest ever real-world study, patients receiving DES had significantly better clinical outcomes than their BMS counterparts, without an associated increase in bleeding or stroke, throughout 30 months of follow-up and across all pre-specified subgroups.

Long-Term Mortality of Patients Undergoing Cardiac Catheterization for ST-Elevation and Non―ST-Elevation Myocardial Infarction

Background— There are limited contemporary data comparing long-term outcomes after cardiac catheterization for ST-segment elevation myocardial infarction (STEMI) and non-STEMI (NSTEMI). Methods and Results— We studied patients undergoing cardiac catheterization for STEMI (n=2413) and NSTEMI (n=1974) between 1999 and 2005 with at least 1 significant coronary lesion ≥75%. We compared adjusted mortality rates over restricted time intervals and the differential impact of early revascularization on mortality stratified by ST-elevation status. Between 1999 and 2007, 1274 patients died, with a median follow-up of 4 years. A piece-wise analysis showed a higher adjusted mortality risk for STEMI during the first 2 months (adjusted hazard ratio, 1.85; 95% confidence interval, 1.45 to 2.38) and a lower adjusted mortality risk for STEMI after 2 months (adjusted hazard ratio, 0.68; 95% confidence interval, 0.59 to 0.83). Compared with late or no revascularization, early revascularization was associated with a lower adjusted risk of mortality for both STEMI (adjusted hazard ratio, 0.73; 95% confidence interval, 0.58 to 0.90) and NSTEMI (adjusted hazard ratio, 0.76; 95% confidence interval, 0.65 to 0.89) (P for interaction=0.22). Conclusions— Among a contemporary cohort of acute MI patients with significant coronary disease during cardiac catheterization, STEMI was associated with a higher risk of short-term mortality, but NSTEMI was associated with a higher risk of long-term mortality. Early revascularization was associated with a similar improvement in long-term outcomes for both STEMI and NSTEMI. These data suggest that in clinical investigations of early revascularization among patients with NSTEMI, extended follow-up may be necessary to demonstrate treatment benefit.

A Registry-Based Randomized Trial Comparing Radial and Femoral Approaches in Women Undergoing Percutaneous Coronary Intervention : The SAFE-PCI for Women (Study of Access Site for Enhancement of PCI for Women) Trial

OBJECTIVES This study sought to determine the effect of radial access on outcomes in women undergoing percutaneous coronary intervention (PCI) using a registry-based randomized trial. BACKGROUND Women are at increased risk of bleeding and vascular complications after PCI. The role of radial access in women is unclear. METHODS Women undergoing cardiac catheterization or PCI were randomized to radial or femoral arterial access. Data from the CathPCI Registry and trial-specific data were merged into a final study database. The primary efficacy endpoint was Bleeding Academic Research Consortium type 2, 3, or 5 bleeding or vascular complications requiring intervention. The primary feasibility endpoint was access site crossover. The primary analysis cohort was the subgroup undergoing PCI; sensitivity analyses were conducted in the total randomized population. RESULTS The trial was stopped early for a lower than expected event rate. A total of 1,787 women (691 undergoing PCI) were randomized at 60 sites. There was no significant difference in the primary efficacy endpoint between radial or femoral access among women undergoing PCI (radial 1.2% vs. 2.9% femoral, odds ratio [OR]: 0.39; 95% confidence interval [CI]: 0.12 to 1.27); among women undergoing cardiac catheterization or PCI, radial access significantly reduced bleeding and vascular complications (0.6% vs. 1.7%; OR: 0.32; 95% CI: 0.12 to 0.90). Access site crossover was significantly higher among women assigned to radial access (PCI cohort: 6.1% vs. 1.7%; OR: 3.65; 95% CI: 1.45 to 9.17); total randomized cohort: (6.7% vs. 1.9%; OR: 3.70; 95% CI: 2.14 to 6.40). More women preferred radial access. CONCLUSIONS In this pragmatic trial, which was terminated early, the radial approach did not significantly reduce bleeding or vascular complications in women undergoing PCI. Access site crossover occurred more often in women assigned to radial access. (SAFE-PCI for Women; NCT01406236).

Clinical Outcomes of Bivalirudin for Ischemic Heart Disease

BACKGROUND Current treatment strategies for percutaneous coronary revascularization and acute coronary syndromes incorporate thrombin inhibition with either unfractionated or fractionated heparin. The peptide bivalirudin (Hirulog) is a direct thrombin inhibitor whose pharmacological properties differ from those of heparin. We conducted a systematic overview (meta-analysis) to assess the effect of bivalirudin on 4 end points: death, myocardial infarction, major hemorrhage, and the composite of death or infarction. METHODS AND RESULTS Six trials (5674 patients) represent the randomized, controlled bivalirudin experience, including 4603 patients undergoing elective percutaneous coronary revascularization and 1071 patients with acute coronary syndromes. ORs for the 4 clinical end points were calculated for each trial. Four trials (4973 patients) that compared bivalirudin with heparin were combined with the use of a random-effects model. In these trials, bivalirudin was associated with a significant reduction in the composite of death or infarction (OR 0.73, 95% CI 0.57 to 0.95; P=0.02) at 30 to 50 days, or 14 fewer events per 1000 patients so treated. There also was a significant reduction in major hemorrhage for the same trials (OR 0.41, 95% CI 0. 32 to 0.52; P<0.001, or 58 fewer events per 1000 patients so treated). A similar analysis combined 2 dose-ranging trials (701 patients) that compared therapeutic (activated partial thromboplastin time more than twice the control time) with subtherapeutic bivalirudin anticoagulation (activated partial thromboplastin time less than twice the control time). CONCLUSIONS Bivalirudin is at least as effective as heparin, with clearly superior safety. Thus, it provides an unprecedented net clinical benefit over heparin in patients with ischemic heart disease.

Meta-Analysis of Survival With Platelet Glycoprotein IIb/IIIa Antagonists for Percutaneous Coronary Interventions

We performed a cumulative meta-analysis of available studies to evaluate the effect of intravenous platelet glycoprotein (GP) IIb/IIIa antagonists on survival at 30 days and 6 months after percutaneous coronary intervention (PCI). Compounds that block the GP IIb/IIIa receptor substantially reduce myocardial infarctions (MIs) and repeat revascularization. We included 12 trials, which enrolled 20,186 patients in all, in the analysis. Overall, 30-day mortality was significantly reduced with GP IIb/IIIa inhibition (odds ratio 0.73, 95% confidence interval 0.55 to 0.96, p = 0.024). Although 10 of the 12 trials showed a beneficial effect of GP IIb/IIIa inhibitor treatment on mortality, no individual trial detected a statistically significant mortality benefit. The 30-day mortality benefit became significant at the p <0.05 level with addition of the ADMIRAL trial and was further enhanced by the CADILLAC trial. No significant heterogeneity was detected in the collection of trials. At 6 months, the odds ratio was 0.84 (95% confidence interval 0.69 to 1.03, p = 0.087). This survival benefit amounts to preventing approximately 1 of every 3 deaths that occur within 30 days after PCI, saving 2.8 lives/1,000 patients treated (number needed to treat, 357). Thus, patients who undergo PCI can expect significantly lower 30-day mortality, in addition to known reductions in nonfatal MI and repeat procedures, with GP IIb/IIa inhibition. There also is increasing evidence that mortality reductions are preserved at 6 months.