Association of diabetes and glycemic control with left atrial function: The Atherosclerosis Risk in Communities (ARIC) study

BACKGROUND AND AIMS

Although glycemic status is associated with impaired cardiac structure and function, less is known on left atrial (LA) function across the glycemic spectrum. We evaluated the association of diabetes and glycemic control with LA function in a community-based cohort of older adults.

METHODS AND RESULTS

This cross-sectional analysis included 5075 participants from the Atherosclerosis Risk in Communities Study (mean age 75.5 years, 58 % women, and 20 % Black adults) with echocardiographic strain data for LA reservoir, conduit, and contractile function. Multivariable linear regression was used to assess associations of diabetes status and glycemic control with LA function. In participants without diabetes, we used ordinal linear regression to evaluate associations of fasting glucose and HbA1c with LA function. Compared to individuals with a normal fasting glucose, prevalent diabetes was associated with 0.68 % lower LA conduit function (95 % confidence interval (CI): 1.11 to -0.25) and prediabetes a 0.47 % reduction (95 % CI: 0.85 to -0.09) in fully adjusted analyses. Persons with diabetes and high HbA1c (HgbA1c ≥ 7 % vs <7 %) had 1.05 % lower LA conduit function (95 % CI: 1.63, -0.48). Among individuals without diagnosed diabetes, higher fasting glucose, but not HbA1c, was significantly associated with worse LA conduit function. No significant associations were observed for LA reservoir and contractile function.

CONCLUSIONS

A history of diabetes, prediabetes, and higher fasting glucose levels in persons without diabetes were associated with worse LA conduit function. Corroborative research is needed in prospective cohorts as well as studies that explore underlying mechanisms.

Abstract P669: Inflammatory Markers and Calcification of Coronary Arteries, Aorta and Cardiac Valves in Older Adults: Findings From the Atherosclerosis Risk in Communities (ARIC) Study

Background: Inflammation plays an important role in the pathophysiology of atherosclerosis. However, inflammatory biomarkers have been found to have a weak association with coronary artery calcium (CAC), a representative measure of subclinical atherosclerosis. Moreover, the existing evidence does not sufficiently explore extra coronary calcium (ECC) in this context.

Aim: To characterize the association of two inflammatory markers, high-sensitivity C-reactive protein (hs-CRP) and galectin-3, with CAC and ECC in a community-based cohort.

Methods: Cardiac CT was performed among 1,934 ARIC participants (age 53-74 years) without coronary heart disease at visit 7 (2018-19). We examined the associations of hs-CRP and galectin-3 measured in middle age at visit 4 (1996-98) by quartile with the presence of CAC and ECC (Agatston score >0 vs. 0) using multivariable logistic regression.

Results: Higher hs-CRP was associated with calcifications in the ascending aorta, aortic valve ring, mitral valve and right coronary artery in the unadjusted model (Table). These associations were mostly attenuated after adjusting for potential confounders, but the associations with ascending aorta and right coronary artery calcifications remained significant (adjusted odds ratio (aOR) = 1.45 [95% CI = 1.02-2.07]) and (1.55 [1.12-2.16]) for the highest vs. lowest quartiles, respectively). Galectin-3 was also independently associated with right coronary artery calcification after adjusting for potential confounders (aOR 1.48 [1.02 - 2.01]) for the highest vs. lowest quartiles). These associations were generally consistent in demographic subgroups.

Conclusions: Both hs-CRP and galectin-3 were associated with calcification of some but not all vascular beds tested, suggesting potentially unique atherosclerotic pathophysiology across different vascular beds. Robust associations of inflammatory markers with right coronary artery calcification deserve further investigation.

News coverage about aspirin as a countervailing force against low-dose aspirin campaign promotion

Organized health promotion efforts sometimes compete with news media, social media, and other sources when providing recommendations for healthy behavior. In recent years, patients have faced a complicated information environment regarding aspirin use as a prevention tool for heart health. We explored the possibility that campaign promotion of low-dose aspirin use might have been undermined by news coverage in the USA detailing controversies regarding aspirin use. Using time series data on low-dose aspirin sales in Minnesota, USA, we assessed whether news coverage of aspirin or audience engagement with the Ask About Aspirin campaign website predicted subsequent changes in low-dose aspirin sales, over and above any secular trend. News coverage predicted actual low-dose aspirin purchases whereas exposure to a state-level campaign did not. While a campaign effort to encourage people at risk to discuss low-dose aspirin use with their health care providers did not generate substantive changes in low-dose aspirin tablet sales in the areas of Minnesota monitored for this study, past news coverage about aspirin use, including news about negative side effects, may have suppressed low-dose aspirin sales during this same period. The extent of news coverage about aspirin and heart health had a negative effect on tablet sales recorded in greater Minnesota approximately a month later in an ARIMA time series model, coefficient = -.014, t = -2.33, p = .02. Presented evidence of news coverage effect suggests health campaign assessment should consider trends in the public information environment as potential countervailing forces.

Promoting Aspirin Use for Cardiovascular Disease Prevention Among an Adult Internet-Using Population: A Pilot Study

Cardiovascular disease prevention strategies include aspirin use as a preventive measure. The internet can be used to raise public awareness, promote healthy lifestyles, and improve disease management. This pilot study describes the feasibility of an educational website to recruit and follow adult internet users to examine whether they talked to their physician about aspirin and initiated aspirin use. As part of a statewide intervention promoting an aspirin regimen to prevent heart attacks and strokes in Minnesota, visitors to the website were encouraged to complete an aspirin candidacy tool. Between October, 2015 and February, 2016, men 45–79 and women 55–79 who identified as aspirin candidates were invited to participate in a 6-month study involving four, 5 min online surveys to examine physician discussions about aspirin, aspirin use, and mobile technology use. During the 5-month recruitment period, 234 adults enrolled in the study. Of the 174 who completed the baseline survey and at least one follow-up survey, 74 (43.5%) did not use aspirin at baseline. During follow-up, 12 (16.2%) talked to their doctor about aspirin and 31 (41.8%) initiated aspirin use. Internet, social media, and mobile technology use were high among this population. An educational website may have provided a cue to action for aspirin discussions with physicians and aspirin initiation. More research is needed to evaluate the utility of on-line tools to increase appropriate aspirin use among internet-using populations.

A Novel Method for Assessing Cardiac Output With the Use of Oxygen Circulation Time

BACKGROUND

We investigated whether a simple breath hold would yield dynamic oxygen (O₂) saturation change and whether the derived circulation time would be useful in assessing cardiac function.

METHODS AND RESULTS

Patients undergoing right heart catheterization for clinical indications (n = 48), including heart failure (HF; n = 24), were prospectively recruited. Each subject was instructed to hold their breath for 20-40 seconds. Lung to finger circulation time (LFCT), defined as the time from the point of rebreathing to nadir O₂ desaturation, was correlated with cardiac output. Among 48 subjects recruited, 37 manifested ≥3% O₂ desaturation allowing for an LFCT measurement. Mean LFCT was 38.5 ± 17.5 seconds (range 18.9-94.7 s). LFCT in patients with a clinical diagnosis of HF was significantly longer than those without (45.9 ± 19.9 s vs 31.5 ± 11.5 s; P = .01). Overall, the LFCT was inversely correlated with cardiac output (Fick: r = -0.56; P < .001 [n = 37]; thermodilution: r = -0.6; P = .001 [n = 27]).

CONCLUSIONS

LFCT is prolonged in low cardiac output. LFCT is a novel method that may be useful to noninvasively assess cardiac function in HF.

Extrachromosomal DNA of pea (Pisum sativum) root-tip cells replicates by strand displacement

In cultured pea roots there is extrachromosomal DNA associated with cells that differentiate from the G(2) phase of the cell cycle that is absent from those that differentiate from the G(1) phase. We examined this extrachromosomal DNA by electron microscopy and found that it consisted of three types: (i) double-stranded linear molecules with single-stranded branches (74%), (ii) double-stranded molecules without branches (26%), and (iii) free single-stranded molecules. The double-stranded molecules with or without branches were similar in length, having a modal length of 10-15 mum. The free single-stranded molecules were shorter and had a mean length of 3.8 mum. The length of the branches attached to the duplex molecules was only slightly less than that of the free form. The duplex molecules with branches were interpreted as configurations reflecting an ongoing strand-displacement process that results in free single-stranded molecules. Finally, measurements on duplex molecules with multiple branches suggested that the extrachromosomal DNA may exist in the form of tandemly repeated sequences.

Replication termini in the rDNA of synchronized pea root cells (Pisum sativum )

In synchronized root cells of Pisum sativum (cv. Alaska) the joining of nascent replicons is delayed until cells reach the S-G(2) boundary or early G(2) phase. To determine if the delayed ligation of nascent chains occurs at specific termination sites, we mapped the location of arrested forks in the ribosomal DNA (rDNA) repeats from cells in late S and G(2) phases. Two-dimensional (neutral-alkaline) agarose electrophoresis and Southern blot hybridization with specific rDNA sequences show that only cells located at the S-G(2) boundary and early G(2) phase produce alkali-released rDNA fragments of discrete size. The released fragments are from a particular restriction fragment, demonstrating that the replication forks stop non-randomly within the rDNA repeats. Indirect end-labeling with probes homologous to one or the other end of the fork-containing restriction fragment shows that there are two termination regions, T(1) and T(2), where forks stop. T(1) is located in the non-transcribed spacer and T(2) is at the junction between the non-transcribed spacer and the 18S gene. The two termini are separated by 1.3 kb. Replication forks stop at identical sites in both the 8.6- and 9.0-kb rDNA repeat size classes indicating that these sites are sequence determined.

Replication of the rRNA and legumin genes in synchronized root cells of pea (Pisum sativum): evidence for transient EcoR I sites in replicating rRNA genes

The temporal pattern of replication of the rRNA and legumin genes differs in synchronized pea root cells. The relative number of rRNA genes replicated hourly during the first five hours of S phase ranges between 5 and 10 percent. In late S phase, during hours six through nine, the number of rRNA genes replicated increases reaching a maximum of about 25 percent at the ninth hour. Unlike the rRNA genes, the legumin genes have a wave-like pattern of replication peaking in early S phase at the third hour and again in late S phase at the eighth hour.Replicating rDNA, isolated by benzoylated naphthoylated DEAE-column chromatography, has EcoR I restriction sites that are absent in non-replicating rDNA sequences. The cleavage of these sites is independent of the time of rDNA replication. The transient nature of the EcoR I sites suggests that they exist in a hemimethylated state in parental DNA.The two Hind III repeat-size classes of rDNA of var. Alaska peas are replicated simultaneously as cells progress through S phase. Thus, even if the 9.0 kb and 8.6 kb repeat classes are located on different chromosomes, their temporal order of replication is the same.