Prevalence and correlations of multifocal atrial rhythms in oldest old people. Insights from the Ikaria study

Abstract

Purpose: Multifocal atrial rhythms (MARs), namely multifocal atrial tachycardia and chaotic atrial rhythm, are rare arrhythmias mostly seen in hospitalized patients with several comorbidities to who they imply high in-hospital mortality. We have examined the prevalence of MARs and the associated characteristics in outpatient elderly subjects from Ikaria study. Methods: In this cohort study we included 175 subjects aged 85±7 years (range 75-103). Demographic and clinical characteristics were recorded in all participants. All individuals underwent a thorough echocardiographic examination. ECG was recorded from a 12-lead surface digital recorder and diagnosis was performed by two independent and blinded to the study physicians. The diagnosis of MARs was based on the identification of at least three different P waves contours on the surface ECG, with irregular P-P intervals, and an isoelectric baseline between the P waves. Results: Sinus rhythm was present in 73% of the subjects, atrial fibrillation in 14%, MAR in 7%, paced rhythm in 4% and atrial flutter in 1%. Subjects with MARs as compared to those without were older (92±4 years vs. 85±7, p=0.001) while there was no difference in body mass index (BMI) (26.67±4.71 kgm/m2 vs. 26.94±3.77, p=0.82), creatinine clearance (41.39±13.48 ml/min vs. 50.46±17.08, p=0.14), male gender (33% vs. 51%, p=0.22), serum K+ levels (4.6±0.5 mEq/L vs. 4.6±0.6, p=0.93), smoking habits (8.3% vs. 13.9%, p=0.58), EF (56±5% vs. 57±6%, p=0.74), left atrial volume (48±17 ml vs. 60±26, p=0.16), physical activity status (58% vs. 62%, p=0.87), use of b-blockers (17% vs. 13%, p=0.72), digitalis use (10% vs. 8%, p=0.78) and in the presence of arterial hypertension (AH) (83% vs. 84%, p=0.96), diabetes mellitus (DM) (25% vs. 30%, p=0.72), history of cardiovascular disease (CVD) (18% vs. 20%, p=0.86) and chronic obstructive pulmonary disease (COPD) (38% vs. 16%, p=0.11), Binary logistic regression analysis after adjustment for confounders such as gender, EF, left atrial volume, COPD and creatinine clearance revealed age as the only significant predictor of MARs (OR=1.22, 95% CI: 1.01 to 1.47, p=0.04). For each year increase in age, the prevalence of MARs was raised in average by 22%, independently of other known confounders. Conclusion: In this cohort of oldest old individuals we have documented a high prevalence of MARs which was associated exclusively with increased age. These findings imply the possibility that MARs constitute a common arrhythmia in very old subjects, which prognostic impact needs further investigation in prospective studies.