Ethnic Distribution of ECG Predictors of Atrial Fibrillation and Its Impact on Understanding the Ethnic Distribution of Ischemic Stroke in the Atherosclerosis Risk in Communities (ARIC) Study

Abstract

Background and Purpose-The paradox of the reported low prevalence of atrial fibrillation (AF) in blacks compared with whites despite higher stroke rates in the former could be related to limitations in the current methods used to diagnose AF in population-based studies. Hence, this study aimed to use the ethnic distribution of ECG predictors of AF as measures of AF propensity in different ethnic groups. Methods-The distribution of baseline measures of P-wave terminal force, P-wave duration, P-wave area, and PR duration (referred to as AF predictors) were compared by ethnicity in 15 429 participants (27% black) from the Atherosclerosis Risk in Communities (ARIC) study by unpaired t test, 2 , and logistic-regression analysis, as appropriate. Cox proportional-hazards analysis was used to separately examine the association of AF predictors with incident AF and ischemic stroke. Results-Whereas AF was significantly less common in blacks compared with whites (0.24% vs 0.95%, PϽ0.0001), similar to what has been reported in previous studies, blacks had significantly higher and more abnormal values of AF predictors (PϽ0.0001 for all comparisons). Black ethnicity was significantly associated with abnormal AF predictors compared with whites; odds ratios for different AF predictors ranged from 2.1 to 3.1. AF predictors were significantly and independently associated with AF and ischemic stroke with no significant interaction between ethnicity and AF predictors, findings that further justify using AF predictors as an earlier indicator of future risk of AF and stroke. Conclusions-There is a disconnect between the ethnic distribution of AF predictors and the ethnic distribution of AF, probably because the former, unlike the latter, do not suffer from low sensitivity. These results raise the possibility that blacks might actually have a higher prevalence of AF that might have been missed by previous studies owing to limited methodology, a difference that could partially explain the greater stroke risk in blacks.

Rates of Atrial Fibrillation in Black Versus White Patients With Pacemakers

“…These findings are consistent with the results of several prior studies that found lower rates of AF in black compared with white patients 3, 4, 5, 6, 7, 8, 9, 10, 11. These studies involved analysis of administrative claims data in all patients presenting for acute care,3 prospective ascertainment of AF based on periodic ECG screening and hospitalization records,4, 5, 6, 7, 8 or examination of electronic medical records to identify clinical diagnoses of AF or ECGs showing AF 9, 10.…”

“…A hypothesis that may explain this discordance is that abnormal atrial substrate predisposing to thromboembolism may manifest differently in black and white persons. Although black persons less often manifest AF, they have a significantly higher prevalence of other electrocardiographic signs of left atrial abnormality 4. This suggests that some of the observed racial disparities in stroke rates may be explained by cases of left atrial thromboembolism that currently go unrecognized because they occur in the absence of AF 27.…”

“…Conversely, studies consistently report that black patients have lower rates of atrial fibrillation (AF)—one of the strongest risk factors for stroke2—than white patients 3, 4, 5, 6, 7, 8, 9, 10, 11. It is unclear whether the lower reported rate of AF in black persons represents a truly lower burden of AF or more frequent underdiagnosis of this often paroxysmal dysrhythmia in black persons 12, 13.…”

Associations of Lipoprotein(a) Levels With Incident Atrial Fibrillation and Ischemic Stroke: The ARIC (Atherosclerosis Risk in Communities) Study

“…At each ARIC study visit, a 10‐second 12‐lead ECG was obtained and transmitted to the ARIC ECG Reading Center for coding, interpretation, and storage. All abnormal ECGs were subsequently adjudicated by a trained cardiologist, and both atrial flutter and AF were coded as AF 27. Hospitalizations were detected with annual follow‐up telephone calls and review of local hospital discharges.…”

Association Between Genetic Variation in the <i>SCN10A</i> Gene and Cardiac Conduction Abnormalities in Patients With Hypertrophic Cardiomyopathy

“…13) Longitudinal data from the Framingham Heart Study (FHS) and the Atherosclerosis Risk in Communities Study 14) demonstrate that PR interval prolongation is a predictor of increased AF risk. 15) In addition, PR interval prolongation has been shown in FHS to be an independent predictor of AF in a multifactorial risk model.…”