Capillary Blood Docosahexaenoic Acid Levels Predict Electrocardiographic Markers in a Sample Population of Premenopausal Women

Abstract

Introduction: The relationship between blood N-3 polyunsaturated fatty acid (PUFA) levels and cardiovascular health is known, but direct evidence that N-3 PUFA levels influence electrocardiographic (ECG) parameters is non-existent. In the study described herein, we investigated the relationship between anthropometric biomarkers and capillary blood PUFAs with ECG outputs in a sample population of healthy pre-menopausal women. Method: Twenty-three consenting females were recruited, with the study power analysis sufficiently demonstrated. Food intake, anthropometric and cardiovascular parameters were obtained. Capillary blood was collected for fatty acid chromatographic analysis. Results: Body mass index, haematocrit, heart rate (HR), mean arterial pressure (MAP) and ECG readings all fell within healthy ranges. Principal component analysis-mediated correlations were carried out controlling for combined Components 1 (age, body fat % and waist-to-hip ratio) and 2 (height, HR and MAP) as control variables. Docosahexaenoic acid (DHA) unequivocally decreased the QRS area under the curve (AUC-QRS) regardless of the impact of control variables, with each unit increase in DHA corresponding to a 2.3-unit decrease in AUC-QRS. Mediation analysis revealed a significant overall effect of DHA on AUC-QRS, with the impact of DHA on R wave amplitude accounting for 77% of the total observed effect. Discussion: Our new findings revealed an inverse relationship between AUC-QRS with capillary blood DHA, suggesting that the association between ventricular mass and its QRS depolarising voltage is mediated by DHA. Our findings bridge a knowledge gap on the relationship between ventricular mass and ventricular efficiency. Further research will confirm whether the relationship identified in our study also exists in diseased patients.

Keywords: N-3 polyunsaturated fatty acid; QRS; blood fatty acid; docosahexaenoic acid; mediation analysis.

Figure 1

Increasing values of capillary blood docosahexaenoic acid (C22:6n-3, DHA) are associated with a significant reduction in ventricular depolarisation (AUC-QRS), after accounting for variation in other common anthropometric biomarkers. The regression slope and 95% CIs (shaded interval) are based on an additive multiple linear regression model with DHA and the first two axes from a PCA of six common biomarkers as predictor variables, including Factor 1 (age, body fat % and WHR) and Factor 2 (height, HR and MPA). Only DHA showed a significant relationship with AUC-QRS; further statistical model details are provided in Table 5. Figure 1 was created with the visreg package for R [46].

Figure 2

Graphical representation of the mediation model for the effect of DHA on AUC-QRS. C1 and C2: confounder variables, factor 1 and factor 2; (X) predictor: DHA; (Y) outcome: AUC-QRS; (M) mediator: R wave amplitude. Numbers on arrows between model components are the standardised beta values (effects). Dashed lines show non-significant paths; continuous lines show significant paths. Grey lines show control variable effects; black lines show main model effects.