Background It has recently been reported that atrial fibrillation [AF] is associated with an increased risk of myocardial infarction [MI]. However, the mechanism underlying this association is currently unknown. Further study of the relationship of AF with type of MI [ST elevation MI (STEMI) vs. non-ST elevation MI [NSTEMI] might shed light on the potential mechanisms. Methods and Results We examined the association between AF and incident MI in 14,462 participants [mean age 54 years, 56% women, 26% African Americans] from the Atherosclerosis Risk in Communities study who were free of coronary heart disease at baseline [1987–1989] with follow-up through December 31, 2010. AF cases were identified from study visits electrocardiogram and by review of hospital discharge records. Incident MI and its types were ascertained by an independent adjudication committee. Over a median follow up of 21.6 years, 1374 MI events occurred [829 NSTEMI, 249 STEMI, 296 unclassifiable]. In a multivariable adjusted model, AF [n=1545] as a time-varying variable was associated with a 63% increased risk of MI [HR (95% CI):1.63(1.32–2.02)]. However, AF was associated with NSTEMI [HR (95% CI): 1.80(1.39–2.31)] but not STEMI [HR (95% CI): 0.49(0.18–1.34)]; p-value for hazard ratios comparison=0.004. Combining the unclassifiable MI group with either STEMI or NSTEMI did not change this conclusion. The association between AF and MI, total and NSTEMI, was stronger in women than in men [interaction p-value<0.01 for both]. Conclusions AF is associated with an increased risk of incident MI, especially in women. However, this association is limited to NSTEMI.
BACKGROUND:Limited information exists on the lifetime risk of atrial fibrillation (AF) in African Americans and by socioeconomic status. METHODS:We studied 15 343 participants without AF at baseline from the ARIC (Atherosclerosis Risk in Communities) cohort recruited in 1987 to 1989 from 4 communities in the United States when they were 45 to 64 years of age. Participants have been followed through 2014. Incidence rates of AF were calculated dividing the number of new cases by personyears of follow-up. Lifetime risk of AF was estimated by a modified Kaplan-Meier method considering death as a competing risk. Participants' family income and education were obtained at baseline. RESULTS:We identified 2760 AF cases during a mean follow-up of 21 years. Lifetime risk of AF was 36% (95% confidence interval, 32%-38%) in white men, 30% (95% confidence interval, 26%-32%) in white women, 21% (95% confidence interval, 13%-24%) in African American men, and 22% (95% confidence interval, 16%-25%) in African American women. Regardless of race and sex, incidence rates of AF decreased from the lowest to the highest categories of income and education. In contrast, lifetime risk of AF increased in individuals with higher income and education in most sex-race groups. Cumulative incidence of AF was lower in those with higher income and education compared with their low socioeconomic status counterparts through earlier life but was reversed after age 80.
Although advanced inter-atrial block (aIAB) is an established electrocardiographic phenotype, its prevalence, incidence, and prognostic significance in the general population are unclear. We examined the prevalence, incidence, and prognostic significance of aIAB in 14,625 (mean age=54±5.8 years; 26% black; 55% female) participants from the Atherosclerosis Risk In Communities (ARIC) study. aIAB was detected from digital electrocardiograms recorded during 4 study visits (1987–1989, 1990–1992, 1993–1995, and 1996–1998). Risk factors for the development of aIAB were examined using multivariable Poisson regression models with robust variance estimates. Cox regression was used to compute hazard ratios (HR) and 95% confidence intervals (CI) for the association between aIAB, as a time-dependent variable, and atrial fibrillation (AF). AF was ascertained from study electrocardiogram data, hospital discharge records, and death certificates thorough 2010. A total of 69 (0.5%) participants had aIAB at baseline and 193 (1.3%) developed aIAB during follow-up. The incidence rate for aIAB was 2.27 (95%CI=1.97, 2.61) per 1000 person-years. Risk factors for aIAB development included age, male sex, white race, antihypertensive medication use, low-density lipoprotein cholesterol, body mass index, and systolic blood pressure. In a Cox regression analysis adjusted for socio-demographics, cardiovascular risk factors, and potential confounders, aIAB was associated with an increased risk for AF (HR=3.09, 95%CI=2.51, 3.79). In conclusion, aIAB is not uncommon in the general population. Risk factors for developing aIAB are similar to those for AF and the presence of aIAB is associated with an increased risk for AF.
Aims Mental stress-induced myocardial ischemia (MSIMI) in patients with coronary artery disease (CAD) is associated with adverse cardiovascular outcomes. We aim to assess hemodynamic, neuro-hormonal, endothelial, vasomotor and vascular predictors of MSIMI. Methods and Results We subjected 660 patients with stable CAD to 99mTc sestamibi myocardial perfusion imaging at rest, with mental (speech task) and with conventional (exercise/pharmacological) stress. Endothelium-dependent flow-mediated dilation (FMD), microvascular reactivity [reactive hyperemia index (RHI)] and arterial stiffness [pulse wave velocity (PWV)] were measured at rest and 30-min after mental stress. The digital microvascular vasomotor response during mental stress was assessed using peripheral arterial tonometry (PAT). A total of 106(16.1%) patients had MSIMI. Mental stress was accompanied by significant increases in rate-pressure-product (heart rate x systolic blood pressure; RPP), epinephrine levels and PWV, and significant decreases in FMD and PAT ratio denoting microvascular constriction. In comparison to those with no MSIMI, patients with MSIMI had higher hemodynamic and digital vasoconstrictive responses (p<0.05 for both), but did not differ in epinephrine, endothelial or macrovascular responses. Only presence of ischemia during conventional stress (OR of 7.1, 95%CI of 4.2, 11.9), high hemodynamic response (OR for RPP response ≥ vs < ROC cutoff of 1.8, 95%CI of 1.1, 2.8), and high digital vasoconstriction (OR for PAT ratio < vs ≥ ROC cutoff of 2.1, 95%CI of 1.3, 3.3) were independent predictors of MSIMI. Conclusion Ischemia during conventional stress testing and hemodynamic and vasoconstrictive responses to mental stress can help predict subjects with CAD at greater risk of developing MSIMI.
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