Modifying effect of dual antiplatelet therapy on incidence of stent thrombosis according to implanted drug-eluting stent type

Aim To investigate the putative modifying effect of dual antiplatelet therapy (DAPT) use on the incidence of stent thrombosis at 3 years in patients randomized to Endeavor zotarolimus-eluting stent (E-ZES) or Cypher sirolimus-eluting stent (C-SES). Methods and results Of 8709 patients in PROTECT, 4357 were randomized to E-ZES and 4352 to C-SES. Aspirin was to be given indefinitely, and clopidogrel/ticlopidine for ≥3 months or up to 12 months after implantation. Main outcome measures were definite or probable stent thrombosis at 3 years. Multivariable Cox regression analysis was applied, with stent type, DAPT, and their interaction as the main outcome determinants. Dual antiplatelet therapy adherence remained the same in the E-ZES and C-SES groups (79.6% at 1 year, 32.8% at 2 years, and 21.6% at 3 years). We observed a statistically significant (P = 0.0052) heterogeneity in treatment effect of stent type in relation to DAPT. In the absence of DAPT, stent thrombosis was lower with E-ZES vs. C-SES (adjusted hazard ratio 0.38, 95% confidence interval 0.19, 0.75; P = 0.0056). In the presence of DAPT, no difference was found (1.18; 0.79, 1.77; P = 0.43). Conclusion A strong interaction was observed between drug-eluting stent type and DAPT use, most likely prompted by the vascular healing response induced by the implanted DES system. These results suggest that the incidence of stent thrombosis in DES trials should not be evaluated independently of DAPT use, and the optimal duration of DAPT will likely depend upon stent type (Clinicaltrials.gov number NCT00476957

Event detection using population-based health care databases in randomized clinical trials: a novel research tool in interventional cardiology

Leif Thuesen,1 Lisette Okkels Jensen,2 Hans Henrik Tilsted,3 Michael Mæng,1 Christian Terkelsen,1 Per Thayssen,2 Jan Ravkilde,3 Evald Høj Christiansen,1 Hans Erik Bøtker,1 Morten Madsen,4 Jens F Lassen1 1Department of Cardiology, Aarhus University Hospital, Skejby, Denmark; 2Department of Cardiology, Odense University Hospital, Odense, Denmark; 3Department of Cardiology, Aalborg University Hospital, Aalborg, Denmark; 4Department of Clinical Epidemiology, Aarhus University Hospital, Skejby, Denmark Aim: To describe a new research tool, designed to reflect routine clinical practice and relying on population-based health care databases to detect clinical events in randomized clinical trials. Background: Randomized clinical trials often focus on short-term efficacy and safety in a controlled environment. Trial follow-up may be linked with study-related investigations and differ from routine clinical practice. Because treatment and control in randomized trials differ from daily practice, trial results may have reduced general applicability and may be of limited value in clinical decision-making. Further, it is economically very costly to conduct randomized clinical trials. Methods and results: Population-based health care databases collect data continuously and prospectively, and make it possible to monitor lifelong outcomes of cardiac interventions in large numbers of patients. This strengthens external validity by eliminating the effects of study-related monitoring or diagnostic tests. Further, follow-up data can be obtained at low expense. Importantly, data sources encompassing a complete population are likely to reflect clinical practice. Because population-based health care databases collect data for quality-control and administrative purposes unrelated to scientific investigations, certain biases, such as nonresponse bias, recall bias, and bias from losses to follow-up, can be avoided. Conclusion: Event detection using population-based health care databases is a new research tool in interventional cardiology that may allow large, low-cost, randomized clinical trials to reflect daily clinical practice, covering a broad range of patients and end points with complete lifelong follow-up. Keywords: clinical study, national registries, event detection, PCI, coronary stent

The Western Denmark Cardiac Computed Tomography Registry: a review and validation study

Lene Hüche Nielsen,1 Bjarne Linde Nørgaard,2 Hans Henrik Tilsted,3 Niels Peter Sand,4 Jesper Møller Jensen,2 Morten Bøttcher,5 Axel Diederichsen,6 Jess Lambrechtsen,7 Lone Deibjerg Kristensen,8 Hans Mickley,6 Henrik Munkholm,1 Ole Gøtzsche,2 Lars Lyhne Knudsen,5 Hans Erik Bøtker,2 Lars Pedersen,9 Morten Schmidt,2,9 1Department of Cardiology, Lillbaelt Hospital-Vejle, Vejle, Denmark; 2Department of Cardiology Aarhus University Hospital-Skejby, Aarhus, Denmark; 3Department of Cardiology, Aalborg University Hospital, Aalborg, Denmark; 4Department of Cardiology, Hospital of Southwestern Denmark-Esbjerg, Esbjerg, Denmark; 5Department of Cardiology, Regional Hospital Herning, Herning, Denmark; 6Department of Cardiology, Odense University Hospital, Odense, Denmark; 7Department of Cardiology, Odense University Hospital-Svendborg, Svendborg, Denmark; 8Department of Cardiology, Regional Hospital Silkeborg, Silkeborg, Denmark; 9Department of Clinical Epidemiology, Aarhus University Hosptial, Aarhus, DenmarkBackground: As a subregistry to the Western Denmark Heart Registry (WDHR), the Western Denmark Cardiac Computed Tomography Registry (WDHR-CCTR) is a clinical database established in 2008 to monitor and improve the quality of cardiac computed tomography (CT) in Western Denmark.Objective: We examined the content, data quality, and research potential of the WDHR-CCTR.Methods: We retrieved 2008–2012 data to examine the 1) content; 2) completeness of procedure registration using the Danish National Patient Registry as reference; 3) completeness of variable registration comparing observed vs expected numbers; and 4) positive predictive values as well as negative predictive values of 19 main patient and procedure variables.Results: By December 31, 2012, almost 22,000 cardiac CTs with up to 40 variables for each procedure have been registered. Of these, 87% were coronary CT angiography performed in patients with symptoms indicative of coronary artery disease. Compared with the Danish National Patient Registry, the overall procedure completeness was 72%. However, an additional medical record review of 282 patients registered in the Danish National Patient Registry, but not in the WDHR-CCTR, showed that coronary CT angiographies accounted for only 23% of all nonregistered cardiac CTs, indicating >90% completeness of coronary CT angiographies in the WDHR-CCTR. The completeness of individual variables varied substantially (range: 0%–100%), but was >85% for more than 70% of all variables. Using medical record review of 250 randomly selected patients as reference standard, the positive predictive value for the 19 variables ranged from 89% to 100% (overall 97%), whereas the negative predictive value ranged from 97% to 100% (overall 99%). Stratification by center status showed consistently high positive and negative predictive values for both university (96%/99%) and nonuniversity centers (97%/99%).Conclusion: WDHR-CCTR provides ongoing prospective registration of all cardiac CTs performed in Western Denmark since 2008. Overall, the registry data have a high degree of completeness and validity, making it a valuable tool for clinical epidemiological research. Keywords: coronary computed tomography angiography, database, epidemiology, registrie