Electrical impulse production and propagation abnormalities in nonagerian hearts. Insights from the Ikaria study

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Purpose: Electrocardiography (ECG) is a wide spread convenient and low cost tool with diagnostic and prognostic significance. As few studies have examined the incidence of ECG abnormalities in subjects over 90 years of age, we have examined the incidence of electrical impulse production and propagation abnormalities in a population of nonagenarians enrolled in the Ikaria study. Methods: We included 110 subjects aged 60 to 74 years (1st group of age), 114 aged 75 to 89 years (2nd group) and 61 over 90 years old (3rd group). Several demographic and clinical characteristic were recorder in all individuals. ECG was recorded from a 12-lead surface digital recorded. ECG diagnosis and characterization of abnormalities were performed by two independent, blinded to the study physicians. Results: The mean age of the participants in the 1st, 2nd and 3rd age groups was 72±8, 77±9 and 92±8 years respectively. Between the three age groups there was no difference in the presence of male sex (p=0.99), in body mass index (, p=0.47) in the presence of cardiovascular disease (p=0.78), arterial hypertension (p=0.23) and diabetes mellitus (p=0.37). Subjects in the 3rd group had increased heart rate (73±16bpm vs. 66±11bpm vs. 62±10 bpm, p<0.001), lower prevalence of sinus rhythm (54% vs. 74% vs. 94%, p<0.001) and increased prevalence of a paced rhythm (6.6% vs. 3.6% vs. 0.0%, p=0.04), atrial fibrillation (23.0% vs. 15.2% vs. 5.5%, p=0.04), atrial flutter (3.3% vs. 0.0% vs. 0.0%, p=0.026), multifocal atrial rhythms (MARs) with or without tachycardia (14.8% vs. 4.4% vs. 0.9%, p=0.01) as compared to subjects in 1st and 2nd and groups of age. Between 1st, 2nd and 3rd groups there was no difference in the prevalence of right bundle branch block (5.5% vs. 6.2% vs. 9.8%, p=0.53), left bundle branch block (0.0% vs. 1.8% vs. 1.6%, p=0.38), left anterior fascicular block (10% vs. 16% vs. 23%, p=0.07), bifascicular block (3.6% vs. 5.4% vs. 8.2%, p=0.44) and trifascicular block (0.0% vs. 1.7% vs. 1.6%, p=0.38). Interestingly, a J shape pattern was observed in the prevalence of first degree atrioventricular block (15% vs. 30% vs. 18%, p=0.01) and second degree atrioventricular block (0.0% vs. 3.6% vs. 1.6%, p=0.13) for 1st, 2nd and 3rd groups of age respectively. Conclusion: The incidence of common arrhythmias (such as atrial fibrillation) and heart rate increase with aging whereas sinus rhythm is suppressed. Interestingly, in this sample of oldest old subjects the incidence of MARs, which are rarely encountered in the general population, was approximately 15%. The prognostic impact of the latter finding remains to be clarified.