Prediction of incident atrial fibrillation with GDF-15 and echocardiographic left atrial volumes: data from the Akershus cardiac examination 1950 study

Background

Left atrial structural remodeling is associated with the risk of incident atrial fibrillation, but there is uncertainty as to what echocardiographic left atrial indices that best predict incident atrial fibrillation. GDF-15 is a marker of oxidative stress and inflammation that is closely associated with the risk of stroke, bleeding and mortality in patients with atrial fibrillation. There is, however, limited data regarding its relation with left atrial remodeling and incident atrial fibrillation in the general population.

Purpose

To investigate the association between GDF-15 and left atrial volumes, and their prognostic properties for incident atrial fibrillation in a general population cohort.

Methods

The Akershus Cardiac Examination 1950 Study is a population-based cohort of individuals born in 1950. Comprehensive baseline examinations were performed for 3706 study participants in 2012–2015. Left atrial maximum and minimum volumes were measured, indexed to body surface area yielding LAVimax and LAVimin. Left atrial emptying fraction (LAEF) was calculated as ((LAVimax - LAVimin)/LAVimax)x100%. Individuals with known atrial fibrillation at baseline (n=166) were excluded, leaving 3540 included in this analysis. National health registries provided clinical outcome data regarding atrial fibrillation and death from any cause. Incident atrial fibrillation cases were validated by health records. Atrial flutter was included in the outcome definition. The CHARGE-AF risk score for atrial fibrillation was quantified. Prediction of incident atrial fibrillation was assessed by Cox proportional hazards regression models and visualised by Kaplan-Meier plots.

Results

Mean age at baseline was 63.9±0.7 years and 1763 (49.8%) were female. GDF-15 correlated weakly with LAVimax (r=−0.07, p<0.001) and LAVimin (r=−0.05 p=0.007), but not with LAEF (r=−0.01, p=0.61). During a median follow-up of 6.4 years, incident atrial fibrillation occurred in 135 (3.8%) individuals. Subjects who developed atrial fibrillation had larger LAVimax (30.1±8.3 vs. 26.2±6.9 mL/m2; p<0.001), larger LAVimin (17.1±7.1 vs. 14.1±4.7 mL/m2; p<0.001), and lower LAEF (44.3±10.7 vs. 46.3±9.0%; p=0.019). Concentrations of GDF-15 were not significantly different in those who experienced atrial fibrillation (median 850 [670–1107] vs. 790 [630–1020] ng/L; p=0.06). Left atrial volumes and LAEF, but not GDF-15, were associated with incident atrial fibrillation (Table 1 and Figure 1).

Conclusions

In this population-based cohort study, LAVimax, LAVimin, and LAEF predicted incident atrial fibrillation independently of the CHARGE-AF risk score. GDF-15 was not significantly associated with left atrial structural remodeling or with increased risk of incident atrial fibrillation.

Funding Acknowledgement

Type of funding sources: Public hospital(s). Main funding source(s): Vestre Viken HF, Hospital TrustAkershus University Hospital

Markers of subclinical cardiac disease associate with thresholds for pre-diabetes and diabetes in the general population: data from the ACE 1950 Study

Background

Diabetes mellitus (DM) is associated with increased risk of left ventricular (LV) remodeling and incident heart failure. However, the associations between dysglycemia and subclinical cardiac disease in middle-aged subjects recruited from the general population are not established.

Purpose

To assess the associations of dysglycemia and diagnostic DM thresholds with indices of subclinical cardiac injury and dysfunction in the general population.

Methods

We included participants born in 1950 from the Akershus Cardiac Examination 1950 Study with available biomarker measurements (n=3,688). We used regression models and restricted cubic splines (knots selected from lowest Akaike Information Criterion) to assess the association between glycated hemoglobin A1c (HbA1c) and cardiac troponin T (cTnT), N-terminal pro-B-type natriuretic peptide (NT-proBNP), C-reactive protein (CRP), and echocardiographic parameters. We classified participants with self-reported diagnosis of DM or HbA1c ≥6.5% (48 mmol/L) as DM, participants with HbA1c 5.7–6.5% as pre-DM, and participants with HbA1c <5.7% (39 mmol/mol) as no-DM.

Results

Mean age was 63.9±0.7 years, mean body mass index (BMI) 27.2±4.4 kg/m2, and 1,795 participants (49%) were women. DM was classified in 380 participants (10%), pre-DM in 1,630 participants (44%) and no-DM in 1,678 participants (46%). Increasing HbA1c concentrations were associated with younger age, male sex, obesity, hypercholesterolemia, hypertension, and established coronary artery disease in adjusted analyses. In models adjusted for age, sex, BMI, smoking, hypertension, atrial fibrillation, coronary artery disease and renal function, greater HbA1c was associated with increasing logcTnT and logCRP concentrations, decreasing logNT-proBNP concentrations and worse global longitudinal strain and E/e' (p<0.001 for all). LV mass index was not associated with HbA1c in adjusted models (p=0.23). All five associations were non-linear in the total study population (p<0.001 for non-linearity for all) with robust, linear associations in the pre-DM range of HbA1c, also in adjusted models, and attenuated associations in the no-DM and DM range (Figure 1).

Conclusion

We found robust, linear associations between HbA1c and indices of subclinical cardiac injury and dysfunction among participants classified as pre-DM, while associations were more attenuated among participants with DM. Preventive measures for cardiovascular disease should be considered also in patients with dysglycemia and HbA1c below the established cutoff for DM.

Figure 1. P-values for overall trend

Funding Acknowledgement

Type of funding source: Public hospital(s). Main funding source(s): Akserhus University Hospital