Abstract
Background: Atrial Fibrillation (AF) is present in over 6 million Americans. However, AF occurs less commonly in African Americans and Latinos compared to Caucasians. Major adverse cardiovascular events (MACE) is the leading cause of death in these populations.
Hypothesis : We theorize that glomerular filtration rates (GFR) is an independent risk factor for MACE in African Americans and Latinos with non-valvular AF (NVAF).
Methods: The association of reduced GFR with MACE in NVAF patients was investigated by retrospective chart review. 656 patients were included: 339 with GFR <60 and 317 with GFR ≥60. A Chi-square test, two-sample t-test, or Wilcoxon Rank Sum test was used to test for differences between the two groups in terms of demographic variables and other risk factors. The association between GFR groups and myocardial infarction (MI), stroke, and/or death, was tested using binomial logistic regression. To incorporate the element of time and adjust for covariates, a Cox proportional hazards model analysis was applied for each outcome variable.
Results: As compared to GFR ≥60, a GFR <60 in NVAF was an independent risk factor for MI (HR 1.88 (1.17, 3.04); p=0.009); death (HR 1.63 (1.11, 2.41); p=0.014) and MI, stroke or death ((HR 1.37 (1.05, 1.78); p=0.018). GFR <60 was not an independent risk factor for stroke (HR 1.13 (0.77, 1.65); p=0.529)
Conclusion : Renal dysfunction in patients with NVAF is an independent risk factor for MI, death in and composite of MI, stroke and death in African American and Latino populations.
Abbreviations: GFR: Glomerular filtration rate; MACE: Major adverse cardiovascular events; MI: Myocardial Infarction; HR: Hazard ratio; NVAF: Non-valvular atrial fibrillation
Atrial Fibrillation (AF) is the most prevalent sustained cardiac arrhythmia disorder. More than 6 million Americans have AF and the number of cases is expected to rise to double over the next 30 years (1). Multiple studies have demonstrated that African Americans and Latinos have a lower prevalence of AF despite having a higher burden of traditional AF risk factors when compared with Caucasians (2-5). These minority populations are often underrepresented in large scale AF trials such as AFFIRM (6). Whereas AF prevalence in the overall general population averages about 2%, the estimated prevalence of AF among patients with renal impairment has been reported up to 23% depending upon age, degree of renal impairment and method of detection for AF (7-9). Thus, there exists a large group of patients that have AF with reduced glomerular filtration rate (GFR). A unique association between AF and chronic kidney disease (CKD) is that they share similar risk factors and comorbidities. (9-17). Non-valvular atrial fibrillation (NVAF) is an independent risk factor for cardiovascular morbidity and mortality including death (18, 19), myocardial infarction (MI) (20) and stroke. Specific risk factors have been identified which significantly increase the risk of major adverse cardiovascular events (MACE) in general population with NVAF, as delineated by the CHA2DS2VASc score (19, 21). However, the c statistic for such scoring systems are in the 0.6 range (19). Adding renal dysfunction to such scoring scales has also been shown to improve the positive predictive value of this scoring system (22).
It is not clear that white race confers higher AF risk or that African American and Latino race provide some form of arrhythmia protection. Renal dysfunction as defined by a GFR <60 is recognized as an independent risk factor for MACE (23-27). Traditional risk factors for MACE are more commonly seen in patients with reduced GFR and AF. There is minimal published data that establishes CKD as an independent risk factor for MACE in the African American and Latino AF population. We conducted a retrospective study, in a unique hospital population mainly of African Americans and Latinos, to investigate if reduced GFR is an independent risk factor for MACE primarily in a minority NVAF population.