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Articles by A. S Go
Total Records ( 7 ) for A. S Go
  T. T Tsai , P. M Ho , S Xu , J. D Powers , N. M Carroll , S. M Shetterly , T. M Maddox , J. S Rumsfeld , K Margolis , A. S Go and D. J. Magid
  Background—

Studies suggest that extended clopidogrel use after drug-eluting stent (DES) implantation may decrease the risk of myocardial infarction (MI) and death. Little is known about the competing risk of bleeding from clopidogrel in "real world" clinical practice.

Methods and Results—

We studied 7689 patients undergoing drug-eluting stent implantation enrolled in the HMO Research Network-Stent Registry between 2004 and 2007. Patients were analyzed in 6-month intervals for the occurrence of major bleeding, MI, and death. Clopidogrel use was determined by pharmacy dispensing data. Regression models assessed the association between clopidogrel use and outcomes. Overall, 3603 patients (49.1%) received clopidogrel for >6 months. During a mean follow-up of 418 days (SD, ±168 days), 217 (2.9%) patients died, 279 (3.7%) had a MI, and 271 (3.6%) had major bleeding. After adjustment, patients on clopidogrel therapy were associated with increased major bleeding in all time intervals (0 to 6 months: relative risk (RR)=2.70, 95% CI=1.41 to 5.19; 7 to 12 months: RR=1.71, 95% CI=1.05 to 2.79; 13 to 18 months: RR=2.34, 95% CI=1.26 to 4.34), compared with patients off clopidogrel. Clopidogrel use was also associated with decreased risk of MI for all time intervals (0 to 6 months: RR=0.52, 95% CI=0.36 to 0.77; 7 to 12 months: RR=0.46, 95% CI=0.30 to 0.70; 13 to 18 months: RR=0.53, 95% CI=0.29 to 0.99) and decreased death in the 7 to 12 month interval (RR=0.50, 95% CI=0.30 to 0.83).

Conclusions—

Clopidogrel use was associated with increased major bleeding and decreased MI persisting to 18 months. Bleeding risks on clopidogrel therapy deserve consideration in the ongoing debate regarding optimal clopidogrel duration after PCI.

  E. D Peterson , J. A Spertus , D. J Cohen , M. A Hlatky , A. S Go , B. G Vickrey , J. L Saver and P. C. Hinton
 

Background— The field of outcomes research seeks to define optimal treatment in practice and to promote the rapid full adoption of efficacious therapies into routine clinical care. The American Heart Association (AHA) formed the AHA Pharmaceutical Roundtable (PRT) Outcomes Research Centers Network to accelerate attainment of these goals. Participating centers were intended to carry out state-of-the-art outcomes research in cardiovascular disease and stroke, to train the next generation of investigators, and to support the formation of a collaborative research network.

Program— After a competitive application process, 4 AHA PRT Outcomes Research Centers were selected: Duke Clinical Research Institute; Saint Luke’s Mid America Heart Institute; Stanford University–Kaiser Permanente of Northern California; and University of California, Los Angeles. Each center proposed between 1 and 3 projects organized around a single theme in cardiovascular disease or stroke. Additionally, each center will select and train up to 6 postdoctoral fellows over the next 4 years, and will participate in cross-collaborative activities among the centers.

Conclusions— The AHA PRT Outcomes Research Centers Network is designed to further strengthen the field of cardiovascular disease and stroke outcomes research by fostering innovative research, supporting high quality training, and encouraging center-to-center collaborations.

  P. M Ho , T. T Tsai , T. M Maddox , J. D Powers , N. M Carroll , C Jackevicius , A. S Go , K. L Margolis , T. A DeFor , J. S Rumsfeld and D. J. Magid
 

Background— Adjuvant clopidogrel therapy is essential after drug-eluting stent (DES) implantation. The frequency with which patients delay filling a clopidogrel prescription after DES implantation and the association of this delay with adverse outcomes is unknown.

Methods and Results— This was a retrospective cohort study of patients discharged after DES implantation from 3 large integrated health care systems. Filling a clopidogrel prescription was based on pharmacy dispensing data. The primary end point was all-cause mortality or myocardial infarction (MI). Of 7402 patients discharged after DES implantation, 16% (n=1210) did not fill a clopidogrel prescription on day of discharge and the median time delay was 3 days (interquartile range, 1 to 23 days). Compared with patients filling clopidogrel on day of discharge, patients with any delay in filling clopidogrel had higher death/MI rates during follow-up (14.2% versus 7.9%; P<0.001). In multivariable analysis, patients with any delay had increased risk of death/MI (hazard ratio, 1.53; 95% confidence interval, 1.25 to 1.87). Patients with any delay remained at increased risk of adverse outcomes when the delay cutoff was changed to >1, >3, or >5 days after discharge. Factors associated with delay included older age, prior MI, diabetes, renal failure, prior revascularization, cardiogenic shock, in-hospital bleeding, and clopidogrel use within 24 hours of admission.

Conclusions— One in 6 patients delay filling their index clopidogrel prescription after hospital discharge after DES implantation. This delay was associated with increased risk of adverse outcomes and highlights the importance of the transition period from hospital discharge to outpatient setting as a potential opportunity to improve care delivery and patient outcomes.

  P. M Ho , T. T Tsai , T. Y Wang , S. M Shetterly , C. L Clarke , A. S Go , A Sedrakyan , J. S Rumsfeld , E. D Peterson and D. J. Magid
 

Background— A prior study from the Veterans Health Administration found a clustering of cardiovascular events after clopidogrel cessation. We sought to confirm and expand these findings.

Methods and Results— This was a retrospective cohort study of 2017 patients with acute coronary syndrome discharged on clopidogrel from an integrated health care delivery system. Rates of all-cause mortality or acute myocardial infarction (MI) within 1 year after stopping clopidogrel were assessed among patients who did not have an event before stopping clopidogrel. Death/MI occurred in 4.3% (n=71) of patients. The rates of death/MI were 3.07, 1.62, 0.70, and 0.95 per 10 000 patient-days for the time intervals of 0 to 90, 91 to 180, 181 to 270, and 271 to 360 days after stopping clopidogrel. In multivariable analysis, the 0- to 90-day interval after stopping clopidogrel was associated with higher risk of death/MI (incidence rate ratio, 2.74; 95% confidence interval, 1.69 to 4.44) compared with 91- to 360-day interval. There was a similar trend of increased events after stopping clopidogrel for various subgroups (women versus men, medical therapy versus percutaneous coronary intervention, stent type, and ≥6 months or <6 months of clopidogrel treatment). Among patients taking clopidogrel but stopping ACE inhibitor medications, the event rates were similar in the 0- to 90-day versus the 91- to 360-day interval (2.67 versus 2.91 per 10 000 patient-days; P=0.91).

Conclusions— We observed a clustering of adverse events in the 0 to 90 days after stopping clopidogrel. This clustering of events was not present among patients stopping ACE inhibitors. These findings are consistent with a possible rebound platelet hyper-reactivity after stopping clopidogrel and additional platelet studies are needed to confirm this effect.

  M. C Fang , A. S Go , Y Chang , L. H Borowsky , N. K Pomernacki , N Udaltsova and D. E. Singer
  Background—

Although warfarin is widely recommended to prevent atrial fibrillation-related thromboembolism, many eligible patients do not take warfarin. The objective of this study was to describe factors associated with warfarin discontinuation in patients newly starting warfarin for atrial fibrillation.

Methods and Results—

We identified 4188 subjects newly starting warfarin in the Anticoagulation and Risk Factors in Atrial Fibrillation Study and tracked longitudinal warfarin use through pharmacy and laboratory databases. Data on patient characteristics, international normalized ratio (INR) tests, and incident hospitalizations for hemorrhage were obtained from clinical and laboratory databases. Multivariable Cox regression analysis was used to identify independent predictors of prolonged warfarin discontinuation, defined as ≥180 consecutive days off warfarin. Within 1 year after warfarin initiation, 26.3% of subjects discontinued therapy despite few hospitalizations for hemorrhage (2.3% of patients). The risk of discontinuation was higher in patients aged <65 years (adjusted hazard ratio [HR], 1.33 [95% CI, 1.03 to 1.72] compared to those aged ≥85 years), patients with poorer anticoagulation control (HR, 1.46 [95% CI, 1.42 to 1.49] for every 10% decrease in time in therapeutic INR range), and patients with lower stroke risk (HR, 2.54 [95% CI, 1.86 to 3.47] for CHADS2 stroke risk index of 0 compared to 4 to 6).

Conclusions—

More than 1 in 4 patients newly starting warfarin for atrial fibrillation discontinued therapy in the first year despite a low overall hemorrhage rate. Individuals deriving potentially less benefit from warfarin, including those with younger age, fewer stroke risk factors, and poorer INR control, were less likely to remain on warfarin. Maximizing the benefits of anticoagulation for atrial fibrillation depends on determining which patients are most appropriately initiated and maintained on therapy.

  K Sydow , S. P Fortmann , J. M Fair , A Varady , M. A Hlatky , A. S Go , C Iribarren , P. S Tsao and for the ADVANCE Investigators
 

Background: Endothelium-derived nitric oxide plays a crucial role in the regulation of vascular tone and the development of cardiovascular disease. The endogenous nitric oxide synthase inhibitor asymmetric dimethylarginine (ADMA) has emerged as a novel cardiovascular risk factor. ADMA appears to be an independent predictor for cardiovascular and overall mortality. However, the majority of studies investigating the clinical role of ADMA were performed in European study populations with few individuals of other ethnicities.

Methods: We performed a cross-sectional study of 980 healthy, older (age 60–72 years) individuals of different ethnicities living in the San Francisco Bay area and analyzed ADMA plasma concentrations and their relationship to other cardiovascular risk factors. Plasma ADMA concentrations were measured using a recently developed, highly sensitive ELISA.

Results: In our entire sample, we were able to define a reference interval for ADMA plasma concentrations of 0.47 (90% CI 0.46–0.48) µmol/L to 0.85 (0.84–0.89) µmol/L. The mean ADMA concentration was 0.63 (SD 0.11) µmol/L (median 0.61 µmol/L). Mean ADMA concentrations were significantly lower in African Americans (0.60 µmol/L; P < 0.01) and mixed non-Hispanics (0.60 µmol/L; P < 0.05) compared with whites (0.63 µmol/L). ADMA was positively correlated with cystatin-C in both men ( = 0.29) and women ( = 0.37), and median plasma ADMA concentrations increased across cystatin-C quintiles.

Conclusions: ADMA varies nearly 2-fold across a healthy sample of older men and women, correlates with age, body mass index, and renal function, and is different across ethnic groups. Additional studies in a wider age range and including larger ethnic subgroups would be useful.

  J. P Lash , A. S Go , L. J Appel , J He , A Ojo , M Rahman , R. R Townsend , D Xie , D Cifelli , J Cohan , J. C Fink , M. J Fischer , C Gadegbeku , L. L Hamm , J. W Kusek , J. R Landis , A Narva , N Robinson , V Teal , H. I Feldman and the Chronic Renal Insufficiency Cohort (CRIC) Study Group
 

Background and objectives: The Chronic Renal Insufficiency Cohort (CRIC) Study was established to examine risk factors for the progression of chronic kidney disease (CKD) and cardiovascular disease (CVD) in patients with CKD. We examined baseline demographic and clinical characteristics.

Design, setting, participants, & measurements: Seven clinical centers recruited adults who were aged 21 to 74 yr and had CKD using age-based estimated GFR (eGFR) inclusion criteria. At baseline, blood and urine specimens were collected and information regarding health behaviors, diet, quality of life, and functional status was obtained. GFR was measured using radiolabeled iothalamate in one third of participants.

Results: A total of 3612 participants were enrolled with mean age ± SD of 58.2 ± 11.0 yr; 46% were women, and 47% had diabetes. Overall, 45% were non-Hispanic white, 46% were non-Hispanic black, and 5% were Hispanic. Eighty-six percent reported hypertension, 22% coronary disease, and 10% heart failure. Mean body mass index was 32.1 ± 7.9 kg/m2, and 47% had a BP >130/80 mmHg. Mean eGFR was 43.4 ± 13.5 ml/min per 1.73 m2, and median (interquartile range) protein excretion was 0.17 g/24 h (0.07 to 0.81 g/24 h). Lower eGFR was associated with older age, lower socioeconomic and educational level, cigarette smoking, self-reported CVD, peripheral arterial disease, and elevated BP.

Conclusions: Lower level of eGFR was associated with a greater burden of CVD as well as lower socioeconomic and educational status. Long-term follow-up of participants will provide critical insights into the epidemiology of CKD and its relationship to adverse outcomes.

 
 
 
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