Normand, Sharon‐Lise T.

Background: Randomized clinical trials are often criticized for not reflecting real-world practice. To understand the effect of site and patient selection on trial generalizability, we examined US patient and hospital participation within the Dual Antiplatelet Therapy (DAPT) Study, a broadly inclusive trial of PCI patients, using a linked analysis with the CathPCI Registry®. Methods: Within the CathPCI Registry, we identified patients undergoing PCI between September 1, 2009 and July 1, 2011 - the period of DAPT Study enrollment. We compared US patients enrolled in DAPT to CathPCI Registry patients meeting DAPT inclusion criteria. Characteristics of US DAPT sites were also compared to those of hospitals not participating in DAPT. Standardized differences (%) for all variables were estimated, with those greater than 10% considered significant. Results: Among 1,139,932 NCDR patients undergoing PCI, 748374 (65.7%) met the enrollment criteria for DAPT, and 23495 (2.1%) were enrolled. Enrolled patients were younger and had lower rates of prior stroke, CHF and peripheral vascular disease, but were similar with respect to race and gender compared with eligible patients (Table). Of the 1276 hospitals within the NCDR, 309 (24.2%) participated in DAPT. Hospital characteristics differed markedly, with DAPT-participating hospitals being larger (mean beds 468 vs. 311), more often located in urban settings (61.2% vs. 42.6%), more often affiliated with training programs (53.7% vs. 34.1%), and with higher annual PCI volumes (mean annual hospital volume 858 vs. 378 PCIs) compared with non-DAPT hospitals. Conclusions: While liberal inclusion criteria may allow randomized trials to better simulate “real-world” clinical practice, the process of site selection may encourage participation of higher volume, urban hospital settings. These findings are relevant to clinical trial interpretation and implementation of evidence-based practice throughout the healthcare system.

Background In US clinical practice, many patients who undergo placement of an implantable cardioverter‐defibrillator ( ICD ) for primary prevention of sudden cardiac death receive dual‐chamber devices. The superiority of dual‐chamber over single‐chamber devices in reducing the risk of inappropriate ICD shocks in clinical practice has not been established. The objective of this study was to compare risk of adverse outcomes, including inappropriate shocks, between single‐ and dual‐chamber ICD s for primary prevention. Methods and Results We identified patients receiving a single‐ or dual‐chamber ICD for primary prevention who did not have an indication for pacing from 15 hospitals within 7 integrated health delivery systems in the Longitudinal Study of Implantable Cardioverter‐Defibrillators from 2006 to 2009. The primary outcome was time to first inappropriate shock. ICD shocks were adjudicated for appropriateness. Other outcomes included all‐cause hospitalization, heart failure hospitalization, and death. Patient, clinician, and hospital‐level factors were accounted for using propensity score weighting methods. Among 1042 patients without pacing indications, 54.0% (n=563) received a single‐chamber device and 46.0% (n=479) received a dual‐chamber device. In a propensity‐weighted analysis, device type was not significantly associated with inappropriate shock (hazard ratio, 0.91; 95% confidence interval, 0.59–1.38 [ P =0.65]), all‐cause hospitalization (hazard ratio, 1.03; 95% confidence interval, 0.87–1.21 [ P =0.76]), heart failure hospitalization (hazard ratio, 0.93; 95% confidence interval, 0.72–1.21 [ P =0.59]), or death (hazard ratio, 1.19; 95% confidence interval, 0.93–1.53 [ P =0.17]). Conclusions Among patients who received an ICD for primary prevention without indications for pacing, dual‐chamber devices were not associated with lower risk of inappropriate shock or differences in hospitalization or death compared with single‐chamber devices. This study does not justify the use of dual‐chamber devices to minimize inappropriate shocks.

Background Physical activity data are collected automatically by implantable cardioverter‐defibrillators ( ICD s). Though these data potentially provide a quantifiable and easily accessible measure of functional status, its relationship with survival has not been well studied. Methods and Results Patients enrolled in the Boston Scientific LATITUDE remote monitoring system from 2008 to 2012 with ICD s were eligible. Remote monitoring data were used to calculate mean daily activity at baseline (30 to 60 days after implantation), and longitudinally. Cox regression was used to examine the association between survival and increments of 30 minutes/day in both (1) mean baseline activity and (2) time‐varying activity, with both adjusted for demographic and device characteristics. A total of 98 437 patients were followed for a median of 2.2 years (mean age of 67.7±13.1 years; 71.7% male). Mean baseline daily activity was 107.5±66.2 minutes/day. The proportion of patients surviving after 4 years was significantly higher among those in the most versus least active quintile of mean baseline activity (90.5% vs. 50.0%; log‐rank P value, <0.001). Lower mean baseline activity (i.e., incremental difference of 30‐minutes/day) was independently associated with a higher risk of death (adjusted hazard ratio [ AHR ], 1.44; 95% confidence interval [ CI ], 1.427 to 1.462). Time‐varying activity was similarly associated with a higher risk of death ( AHR , 1.48; 95% CI , 1.451 to 1.508), indicating that a patient having 30 minutes per day less activity in a given month has a 48% increased hazard for death when compared to a similar patient in the same month. Conclusions Patient activity measured by ICD s strongly correlates with survival following ICD implantation.