All-cause Mortality and the Risk of Stroke With Selective Aspiration Thrombectomy in Patients With ST-Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention - A Nationwide Retrospective Cohort Study

Data source and study population Using the National Health Insurance Research Database of Taiwan, STEMI patients from July 2009 to December 2011 who received aspiration thrombectomy during PPCI were defined as the thrombectomy group, and the remaining patients were defined as the PCI alone group. ICD-9-CM codes were used to identify underlying comorbidities. Data regarding the prescription of in-hospital and outpatient medications and the utilization of medical devices were also extracted from the NHIRD using ICD-9-CM procedure codes and pharmacology and device codes.

Study outcomes The primary endpoints of this study were all-cause mortality and stroke during hospitalization and at 30 days and 1 year of follow-up. Ischemic and hemorrhagic subtypes of stroke were further identified according to ICD-9-CM codes. All patientswere followed for 1 year or until the outcomes were achieved, whichever came first.

Statistical analysis Propensity score weighting was used to reduce potential differences between the two study groups. The incidence rates of all-cause mortality and stroke were estimated as the total number of events during the follow-up period divided by the person-months at risk. For all-cause mortality, a Cox proportional hazard model was used to obtain hazard ratios (HRs). For stroke, Fine and Gray's competing-risk regression was used to obtain sub-hazard ratios (SHRs). The cumulative incidence of stroke versus follow-up time was plotted rather than the event-free rate, because cumulative incidence function can take the competing risk of death into account. For the thrombectomy group, 95% confidence intervals (CIs) of the HRs and SHRs were calculated using the PCI alone group as the referent group.