Background/Purpose: Patients with rheumatoid arthritis (RA) are at increased risk of cardiovascular morbidity and mortality. This risk persists even when RA disease characteristics are taken into account. Heart rate corrected QT interval (QTc) obtained on standard electrocardiogram (EKG) represents ventricular repolarization. QTc prolongation is related to increased cardiovascular mortality. The primary purpose our study is to determine the impact of QTc prolongation on mortality in patients with RA.

Methods: A population based inception cohort of patients with RA fulfilling 1987 ACR criteria in 1988-2007 was identified, along with an age and sex matched comparison cohort and followed until death, migration or 12-31-2008. Data were collected on EKG variables (heart rate, QRS interval, QT interval, QT interval corrected for heart rate calculated using the Bazett’s formula(QTc), atrial fibrillation, atrial flutter, supraventricular tachycardia, bundle branch block, paced rhythm, and ST-T wave changes), medications known to prolong QT interval, electrolytes, cardiovascular risk factors and disease status (hypertension, DM, lipids, BMI, smoking status, myocardial infarction, cardiovascular death, sudden death, heart failure), RA disease characteristics (erythrocyte sedimentation rate [ESR], rheumatoid factor, large joint swelling, joint erosions, destructive changes on radiographs, extraarticular manifestations of RA). Cox proportional hazards models were used as to examine QTc prolongation as predictor of mortality.

Results: Among 650 RA and 650 non RA patients, QTc prolongation prior to RA incidence/index date was similar in RA (15%) and non RA (18%). During follow-up, the cumulative incidence of QTc prolongation was higher among RA (48% at 20 years after RA incidence) than non-RA (38% at 20 years after index date; p= 0.004). This difference remained significant (RA: 22%, non RA: 17% at 20 years, p = .025) after excluding QTc prolongation in the presence of EKG variables, electrolytes and QT prolonging medications. Elevated ESR at RA diagnosis was associated with developing prolonged QTc (Hazard ratio [HR}: 1.14 per 10 mm/hr increase; 95% confidence interval [CI]: 1.03-1.27). QTc prolongation was not significantly associated with all-cause mortality in RA patients (HR: 1.28; 95% CI: -.91-1.81, p=0.16) or coronary heart disease mortality (HR: 1.10; 95% CI:0.43-2.86, p= 0.83) adjusted for age, sex and calendar year of RA incidence/index.

Conclusion: RA patients have a significantly elevated risk of developing prolonged QTc interval. Prolonged QTc was not associated with all cause and coronary heart disease mortality in RA patients. The clinical implications of these findings and their relationship to sudden cardiac death in RA require further study.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/prolongation-of-qt-interval-in-patients-with-rheumatoid-arthritis-and-its-impact-on-mortality-results-from-a-population-based-study/