Michael Nguyen

Evaluation of long-term clinical and health service outcomes following coronary artery revascularisation in Western Australia (WACARP): a population-based cohort study protocol

Introduction Coronary artery bypass grafting (CABG) and percutaneous coronary interventions (PCI) are procedures commonly performed on patients with significant obstructive coronary artery disease to relieve symptoms of ischaemia, improve survival or both. Although the efficacy of both procedures at the individual level has been established, the impact of advances in coronary artery revascularisation procedures (CARP) on long-term outcomes and cost-effectiveness at the population level are yet to be assessed. Our aim is to evaluate a minimum of 6-year outcomes and costs for the total population of patients who had CARP in Western Australia (WA) in 2000–2005. Methods and analysis This retrospective population cohort study will link clinical and administrative health data for a previously defined cohort including all patients in WA who had a CARP in the period 2000–2005. The cohort consists of 19 014 patients who had 21 175 procedures (15 429 PCI and 5746 CABG). We are now collecting a minimum of 6 years follow-up of morbidity and mortality data for the cohort using the WA Data Linkage System, clinical registries and hospital records, with 12 years follow-up for cases in the year 2000. Comparison of long-term outcomes for different CARP will be reported (PCI vs CABG; bare metal stents vs drug-eluting stents vs CABG). Cost-effectiveness analysis of CARP from the perspective of the healthcare sector will be performed using individual level cost data and average costs from Australian Refined Diagnosis Related Groups. Ethics and dissemination This study has received ethics approval from the University of Western Australia, the Western Australian Department of Health and all participating hospitals. Being a large population cohort study, approval included a waiver of informed consent. All findings will be presented at local, national and international healthcare/academic conferences and published in peer-reviewed journals.

Effect of Coronary Target Lesion Revascularization on Late Cardiac Events After Insertion of Sirolimus-Eluting or Bare Metal Stents

Restenosis is associated with acute myocardial infarction (MI) either at presentation or related to complications of target lesion revascularization (TLR). The cumulative late effect of TLR after drug-eluting or bare metal stent placement on cardiac death or MI is uncertain. Of the 1,057 patients with one native coronary lesion randomized to a sirolimus-eluting stent or bare metal stent in the Sirolimus-Eluting Stent in De Novo Native Coronary Lesions (SIRIUS) trial, the 983 who survived free of MI for the first 30 days were evaluated for the primary outcome of cardiac death or MI for 5 years. Patients with events occurring at or after TLR were assigned to TLR group. Cox proportional hazards regression analysis with TLR as a time-dependent variable and adjustment for baseline clinical and demographic covariates was used to assess the independent effect of TLR on the primary outcome. TLR occurred in 160 patients (16.3%) and was an independent predictor of the primary end point (hazard ratio 2.8, 95% confidence interval 1.7 to 4.5). This association was significant for sirolimus-eluting stents and bare metal stents. TLR was also associated with an increased risk of subsequent stent thrombosis and nontarget vessel revascularization. Intracoronary brachytherapy in the TLR group was associated with an increased risk of cardiac death or MI. In conclusion, restenosis requiring TLR was associated with an increased risk of cardiac death or MI occurring at TLR and during the subsequent 5 years.

Impact of the introduction of drug eluting stents on clinical outcomes in patients undergoing percutaneous and surgical coronary artery revascularisation procedures in Western Australia

BackgroundIncreasing rates of percutaneous coronary intervention (PCI) and decreasing rates of coronary artery bypass graft (CABG) surgery followed the introduction of drug eluting stents in Western Australia in 2002. We assessed the impact of these changes on one-year outcomes for the total population of patients undergoing coronary artery revascularisation procedures (CARP) in Western Australia between 2000-2004.MethodsClinical and linked administrative data (inpatient admissions and death) were merged for all patients who had their first CARP with stent or CABG in Western Australia between 2000-2004. The clinical data were collected from all hospitals in Western Australia where CARP procedures are performed. We calculated the unadjusted (Kaplan-Meier) and adjusted (Cox) risks for one-year death (all-cause), death (all-cause) or admission for myocardial infarction (MI), target vessel revascularisation (TVR) and the composite outcome of death/MI/TVR (major adverse cardiac events, MACE).ResultsOver the study period, there were 14,118 index CARPs. The use of drug eluting stents increased from 0% to 95.8% of PCI procedures, and PCI procedures increased from 61.1% to 74.4% of all CARPS. There were no temporal changes in adjusted one-year mortality or death/MI. Overall, adjusted one-year MACE fell from 11.3% in 2000 to 8.5% in 2004 (p<0.0001) due to a significant reduction in TVR in the PCI group.ConclusionThe introduction of drug eluting stents and resulting changes in coronary revascularisation strategies were not associated with changes in the one-year risk of major clinical endpoints (death or death/MI), but were associated with a significant reduction in the risk of MACE, driven entirely by a reduction in TVR after PCI. This real world study supports the effectiveness of drug eluting stents in reducing repeat procedures in the total CARP population without increasing the risk of death or MI.