Chronotropic effects and mechanisms of long-chain omega-3 polyunsaturated fatty acids on heartbeat: the latest insights

Unraveling the discrepancies between REDUCE-IT and STRENGTH trials with omega-3 fatty acids: new analytical approaches

Two large-scale, randomized, double-blind, placebo-controlled trials-REDUCE-IT and STRENGTH-have garnered significant attention in cardiovascular medicine. Both trials aimed to evaluate the effects of prolonged administration of nutritional lipids, specifically omega-3 fatty acids, on major adverse cardiovascular events (MACEs) in high-risk patients undergoing statin therapy. REDUCE-IT used eicosapentaenoic acid (EPA) ethyl ester with mineral oil as a control, while STRENGTH utilized a carboxylic acid formulation of both EPA and docosahexaenoic acid (DHA) with corn oil as a control. Notably, REDUCE-IT demonstrated a reduction in MACE risk with EPA, whereas STRENGTH showed no such benefit with the combination of EPA and DHA. Despite extensive and insightful discussions following the publication of these trials, the underlying reasons for this discrepancy remain elusive. We posit that further investigation into resting heart rate (RHR), heart rate variability (HRV), and ethnic subgroup data-collected but not fully explored-is critical to unraveling the divergent outcomes of the REDUCE-IT and STRENGTH trials. These additional analyses could provide pivotal insights into the mechanisms driving the differential effects of omega-3 fatty acids in high-risk cardiovascular patients. Given that previous discussions have not fully addressed these potential variables, exploring them may illuminate unexplored pathways and offer a deeper understanding of the mechanistic and clinical roles of omega-3 s in cardiovascular health. We hypothesize that by delving into these under-analyzed factors, we can not only clarify the discrepancies between the trials but also advance our broader understanding of cardiovascular nutrition and medicine.

A meta-analysis and systematic review of randomized clinical trials on the effect of coffee consumption on heart rate

CONTEXT

Resting heart rate (HR) is increasingly recognized as an indicator of disease and overall morbidity and mortality. Whether chronic coffee consumption affects resting HR is an important consideration for individual consumers as well as from a public health perspective.

OBJECTIVE

A meta-analysis of randomized controlled trials (RCTs) was conducted to examine the effectiveness of coffee consumption on resting HR.

DATA SOURCES

Original RCTs assessing the effect of coffee consumption on resting HR and published prior to March 2023 were identified by searching online databases, including PubMed, Web of Science, and Cochrane Library databases.

DATA EXTRACTION AND ANALYSIS

Data searches and extraction and risk-of-bias assessments were performed according to the Cochrane guidelines, and the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines for systematic reviews were followed. Data on study characteristics, type, and amount of coffee and net change and measurement resting HR were extracted. A random-effects or a fixed-effects model was used to estimate the pooled effect sizes. Homogeneity was determined with the Cochran Q test, and publication bias was assessed through Begg's test, Egger's test, and funnel plots.

RESULTS

A total of 6 RCTs with 11 intervention trials or arms involving 485 individuals were included. The participants were generally healthy, although some had hypertension, hypercholesterolemia, or were overweight. The trial duration ranged from 2 weeks to 24 weeks. The overall pooled analysis showed that coffee consumption resulted in a negligible increase in resting HR of 0.40 beats per minute (95% CI: -0.78 to 1.57; P = 0.506), which was statistically insignificant. Subgroup analysis of all specified categories was consistent with the overall analysis. No heterogeneity was observed among included trials (I2 = 0.0%, P = 0.756).

CONCLUSION

The results of the present meta-analysis study demonstrate that daily coffee consumption of 3 to 6 cups for a period of 2 to 24 weeks has no statistically significant effect on resting HR.

DHA Supplementation During Pregnancy Enhances Maternal Vagally Mediated Cardiac Autonomic Control in Humans

BACKGROUND

DHA is an essential omega-3 (ω-3; n-3) fatty acid that has well-established benefits for the fetus. DHA also has the potential to influence the health of the mother, but this area is understudied.

OBJECTIVES

The objective of this secondary analysis was to determine if DHA was related to maternal heart rate (HR) and heart rate variability (HRV) metrics in a large cohort of pregnant women.

METHODS

In the parent trial (1R01HD086001) eligible participants (≥18 y old, English speaking, carrying a singleton pregnancy, 12-20 wk of gestation) were randomly assigned to consume 200 mg/d or 800 mg/d DHA for the duration of their pregnancy (n = 300). Weight, blood pressure, and magnetocardiograms (MCGs) were collected at 32 wk and 36 wk of gestation (n = 221). Measures of HR and HRV in time-, frequency-, and nonlinear-domains were determined from the isolated maternal MCG. Treatment group and timepoint were examined as predictors in association with HR and HRV metrics using random-intercept mixed-effects ANOVA unadjusted and adjusted models accounting for weight and dietary DHA intake.

RESULTS

Women receiving the higher dose of DHA (800 mg/d) during pregnancy had lower HR, lower sympathetic index, higher vagally mediated HRV indices, and greater HRV complexity when compared with the women who received the lower dose (200 mg/d; all P < 0.05). All the dose relations remained significant even after controlling for the effect of time, maternal weight, and dietary DHA intake.

CONCLUSIONS

DHA supplementation increases vagal tone in pregnant women. Longitudinal studies examining the potential link between DHA, enhanced vagal tone, and reported reduction in early preterm birth are warranted.

Dysautonomia in Children with Post-Acute Sequelae of Coronavirus 2019 Disease and/or Vaccination

Long-term health problems such as fatigue, palpitations, syncope, and dizziness are well-known in patients after COVID-19 (post-acute sequelae of coronavirus (PASC)). More recently, comparable problems have been noticed after the SARS-CoV-2 vaccination (post-VAC). The pathophysiology of these problems is not well-understood. Methods: In 38 children and young adults, we tested if these health problems were related to dysautonomia in an active standing test (Group 1: 19 patients after COVID-19; Group 2: 12 patients with a breakthrough infection despite a vaccination; and Group 3: 7 patients after a vaccination without COVID-19). The data were compared with a control group of 47 healthy age-matched patients, as recently published. Results: All patients had a normal left ventricular function as measured by echocardiography. Significantly elevated diastolic blood pressure in all patient groups indicated a regulatory cardiovascular problem. Compared with the healthy control group, the patient groups showed significantly elevated heart rates whilst lying and standing, with significantly higher heart rate increases. The stress index was significantly enhanced in all patient groups whilst lying and standing. Significantly decreased pNN20 values, mostly whilst standing, indicated a lower vagus activity in all patient groups. The respiratory rates were significantly elevated in Groups 1 and 2. Conclusion: The uniform increase in the heart rates and stress indices, together with low pNN20 values, indicated dysautonomia in children with health problems after COVID-19 disease and/or vaccination. A total of 8 patients fulfilled the criteria of postural orthostatic tachycardia syndrome and 9 patients of an inappropriate sinus tachycardia, who were successfully treated with omega-3 fatty acid supplementation and pharmacotherapy.

Effect of Probiotics Supplementation on Heart Rate: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

Background and Aims

Probiotics consumption lowers the risk of cardiovascular disease, but whether it affects heart rate (HR) remains controversial. Therefore, our study aimed to assess the chronotropic effects of probiotics on heartbeat via a meta-analysis of randomized clinical trials.

Methods

Relevant studies were identified by searching PubMed, Cochrane library, and Clinical Trials databases up to October 2021. Either a fixed-effects or a random-effects model was used to calculate the pooled effect sizes and 95% confidence intervals (CIs).

Results

This meta-analysis included 13 studies involving 16 interventional trial arms and 931 participants according to inclusion criteria. The overall pooled estimate showed that probiotics supplementation had a slight, but no significant reduction of 0.28 bpm (95% CI: −1.17, 0.60) on HR. Relatively high heterogeneity was observed among included trials (I² = 80.8%, P heterogeneity < 0.001). Subgroup analysis displayed that probiotics supplementation significantly reduced HR by 2.94 bpm (95% CI: −5.06, −0.82) among participants with baseline HR ≥ 75 bpm, by 1.17 bpm (95% CI: −2.34, −0.00) with probiotics dose ≥1 × 10¹⁰ CFU/day, and by 1.43 bpm (95% CI: −2.69, −0.17) with multiple-strain intervention. Meta-regression analysis showed that baseline HR was a major potential effect modifier of probiotics supplementation on lowering HR.

Conclusion

Hitherto, the overall evidence in the literature was insufficient to support the notion that probiotics supplementation has a class effect on HR reduction. However, in subgroup analysis, probiotics reduced HR significantly in those who had higher baseline HR, received a higher dose or multiple strains of probiotics.