Cardiovascular risk prediction using physical performance measures in COPD: results from a multicentre observational study.

OBJECTIVES: Although cardiovascular disease (CVD) is a common comorbidity associated with chronic obstructive pulmonary disease (COPD), it is unknown how to improve prediction of cardiovascular (CV) risk in individuals with COPD. Traditional CV risk scores have been tested in different populations but not uniquely in COPD. The potential of alternative markers to improve CV risk prediction in individuals with COPD is unknown. We aimed to determine the predictive value of conventional CVD risk factors in COPD and to determine if additional markers improve prediction beyond conventional factors. DESIGN: Data from the Evaluation of the Role of Inflammation in Chronic Airways disease cohort, which enrolled 729 individuals with Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage II-IV COPD were used. Linked hospital episode statistics and survival data were prospectively collected for a median 4.6 years of follow-up. SETTING: Five UK centres interested in COPD. PARTICIPANTS: Population-based sample including 714 individuals with spirometry-defined COPD, smoked at least 10 pack years and who were clinically stable for >4 weeks. INTERVENTIONS: Baseline measurements included aortic pulse wave velocity (aPWV), carotid intima-media thickness (CIMT), C reactive protein (CRP), fibrinogen, spirometry and Body mass index, airflow Obstruction, Dyspnoea and Exercise capacity (BODE) Index, 6 min walk test (6MWT) and 4 m gait speed (4MGS) test. PRIMARY AND SECONDARY OUTCOME MEASURES: New occurrence (first event) of fatal or non-fatal hospitalised CVD, and all-cause and cause-specific mortality. RESULTS: Out of 714 participants, 192 (27%) had CV hospitalisation and 6 died due to CVD. The overall CV risk model C-statistic was 0.689 (95% CI 0.688 to 0.691). aPWV and CIMT neither had an association with study outcome nor improved model prediction. CRP, fibrinogen, GOLD stage, BODE Index, 4MGS and 6MWT were associated with the outcome, independently of conventional risk factors (p<0.05 for all). However, only 6MWT improved model discrimination (C=0.727, 95% CI 0.726 to 0.728). CONCLUSION: Poor physical performance defined by the 6MWT improves prediction of CV hospitalisation in individuals with COPD. TRIAL REGISTRATION NUMBER: ID 11101.

Age-dependent atrial arrhythmic phenotype secondary to mitochondrial dysfunction in Pgc-1ß deficient murine hearts.

INTRODUCTION: Ageing and several age-related chronic conditions including obesity, insulin resistance and hypertension are associated with mitochondrial dysfunction and represent independent risk factors for atrial fibrillation (AF). MATERIALS AND METHODS: Atrial arrhythmogenesis was investigated in Langendorff-perfused young (3-4 month) and aged (>12 month), wild type (WT) and peroxisome proliferator activated receptor-γ coactivator-1ß deficient (Pgc-1ß-/-) murine hearts modeling age-dependent chronic mitochondrial dysfunction during regular pacing and programmed electrical stimulation (PES). RESULTS AND DISCUSSION: The Pgc-1ß-/- genotype was associated with a pro-arrhythmic phenotype progressing with age. Young and aged Pgc-1ß-/- hearts showed compromised maximum action potential (AP) depolarization rates, (dV/dt)max, prolonged AP latencies reflecting slowed action potential (AP) conduction, similar effective refractory periods and baseline action potential durations (APD90) but shortened APD90 in APs in response to extrasystolic stimuli at short stimulation intervals. Electrical properties of APs triggering arrhythmia were similar in WT and Pgc-1ß-/- hearts. Pgc-1ß-/- hearts showed accelerated age-dependent fibrotic change relative to WT, with young Pgc-1ß-/- hearts displaying similar fibrotic change as aged WT, and aged Pgc-1ß-/- hearts the greatest fibrotic change. Mitochondrial deficits thus result in an arrhythmic substrate, through slowed AP conduction and altered repolarisation characteristics, arising from alterations in electrophysiological properties and accelerated structural change.