Page 99 - THE EVOLUTION OF EARLY ARTHRITIS AND CARDIOVASCULAR RISK Samina A. Turk

THE RELATION BETWEEN CARDIAC CONDUCTION TIMES
INTRODUCTION
Rheumatoid arthritis (RA) is associated with increased morbidity and mortality, primarily because of cardiovascular (CV) disease(1). More than 50% of all premature deaths in RA are attributable to CV disease, in particular ischemic events such as myocardial infarction (MI) and stroke(2-4). This increased CV risk is already present at the clinical onset of RA(5-7). Traditional CV risk factors are well described in patients with established arthritis and some risk factors are shared, including a higher prevalence of smoking, hypertension, dyslipidemia, and a higher body mass index (BMI) compared with the general population(6;8;9). However, lipid levels are inversely associated with RA disease activity, meaning that higher inflammation levels are associated with lower cholesterol levels. This is paradoxical, because lower cholesterol levels in these patients with active RA disease are associated with an increased CV risk(10).
Further, patients with RA also have a 2-fold increased risk of sudden cardiac death 5 (SCD), mostly due to cardiac arrhythmias(4;8;11). Structural changes due to ischemic
heart disease, congestive heart failure, and systemic inflammation all promote this arrhythmic risk. Prolongation of the QT time corrected for heart rate (QTc) is another
albeit indirect risk factor for arrhythmia in patients with chronic RA (4;8;12;13). Heart rate is also associated with CV events and premature death. Bemelmans and Visseren found that an increase in heart rate of 10 bpm is related to 10%-30% more chance for CV events and premature death(14). Hozawa, et al showed that an increase of 5 bpm in heart rate was associated with a 17% increase in the risk of CV mortality(15). Moreover, drugs used in the treatment of RA such as glucocorticoids and nonsteroidal antiinflammatory drugs may also influence arrhythmic risk(16).
The majority of studies that investigated CV disease in patients with arthritis were performed in patients with established disease(1;17). Because systemic inflammation is already increased years before the clinical onset of arthritis (18) we assessed patients with early arthritis to determine the prevalence of conduction disorders before the start of antiinflammatory treatment and compared this with the general population in which the prevalence of conduction disorders, ranges between 9.1% and 17.3%(19-24). We also studied the effect of inflammation and traditional CV risk factors on conduction times.
MATERIALS AND METHODS
Study population.
The study population comprised a cohort of consecutive patients with early arthritis from the Early Arthritis Cohort at Reade in Amsterdam, the Netherlands. This ongoing cohort includes patients aged over 17 years with at least 2 swollen joints, a symptom duration <2 years, and no prior treatment with disease-modifying antirheumatic drugs (DMARD). Diagnosis of RA was according to the American College of Rheumatology
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