The relationship between blood pressure and risk of atrial fibrillation: a Mendelian randomization study

Association of Lipoprotein(a) with arterial stiffness: A Mendelian randomization study

BACKGROUND

In this study we used Mendelian randomization (MR) to investigate the potential causal association of lipoprotein (a) [Lp(a)] levels with pulse wave velocity (PWV).

METHODS

Genetic variants associated with Lp(a) were retrieved from the UK Biobank GWAS (N = 290,497). A non- overlapping GWAS based on a European cohort (N = 7,000) was used to obtain genetic associations with PWV (outcome) and utilized two different measures for the same trait, brachial-ankle (baPWV) and carotid-femoral (cfPWV) PWV. We applied a two-sample MR using the inverse variance weighting method (IVW) and a series of sensitivity analyses for 170 SNPs that were selected as instrumental variables (IVs).

RESULTS

Our analyses do not support a causal association between Lp(a) and PWV for neither measurement [βiwv(baPWV) = -.0005, p = .8 and βiwv(cfPWV) = -.006, p = .16]. The above findings were consistent across sensitivity analyses including weighted median, mode-based estimation, MR-Egger regression and MR-PRESSO.

CONCLUSION

We did not find evidence indicating that Lp(a) is causally associated with PWV, the gold standard marker of arterial stiffness.

Higher Cumulative Blood Pressure in Midlife Predicts an Increased Risk of Atrial Fibrillation: Evidence From the Atherosclerosis Risk in Communities Study

BACKGROUND

Elevated blood pressure (BP) is reportedly associated with an increased risk of atrial fibrillation (AF). However, the association between cumulative BP exposure in midlife and incident AF in mid-to-late life remains unclear.

METHODS AND RESULTS

Participants enrolled in the ARIC (Atherosclerosis Risk in Communities) study with 4 consecutive BP measurements and no prevalent AF at baseline were included. Cumulative BP was calculated as the area under the curve from visit 1 to visit 4. Incident AF was identified by study visit ECGs, hospital discharge codes, or death certificates. A total of 9892 participants were included (44.6% men and mean age 62.9±5.7 years at visit 4) with 1550 (15.7%) individuals who developed new-onset AF during an average follow-up of 15.4 years. The incidence rates of AF per 1000 person-years across the 4 quartiles of cumulative systolic BP were 7.9, 9.2, 12.5, and 16.9, respectively. After multivariable adjustment, the hazard ratios for incident AF among participants in the highest quartile of cumulative systolic BP, pulse pressure, and mean arterial pressure were 1.48 (95% CI, 1.27-1.72), 1.81 (95% CI, 1.53-2.13), and 1.22 (95% CI, 1.05-1.41), respectively, compared with those in the lowest quartile. The addition of cumulative systolic BP or pulse pressure slightly improved the ability to predict new-onset AF.

CONCLUSIONS

Higher exposure to cumulative systolic BP, pulse pressure, and mean arterial pressure was significantly associated with increased risk of incident AF.

Systolic Blood Pressure Time in Target Range and Incident Atrial Fibrillation in Patients With Hypertension: Insights From the SPRINT Trial

BACKGROUND

Systolic blood pressure (SBP) time in target range (TTR) indicates the mean value, exposure time, and variability in blood pressure over time. The prognostic value of SBP TTR for incident atrial fibrillation (AF) in patients with hypertension is unclear.

METHODS

We performed a post hoc analysis of SPRINT (Systolic Blood Pressure Intervention Trial), a randomized controlled trial comparing intensive (<120 mm Hg) and standard (<140 mm Hg) SBP interventions in participants with hypertension. SBP target ranges for intensive and standard arms were defined as 110 to 130 and 120 to 140 mm Hg, respectively. TTR was calculated by linear interpolation method using SBP from months 0 to 3. We used Cox proportional regression models to assess the association of SBP TTR with incident AF.

RESULTS

Among 7939 participants included in this analysis, 187 incident AF cases occurred during follow-up. After multivariable adjustment, a 10% increase in SBP TTR was independently associated with a 7% lower risk of incident AF (hazard ratio, 0.93 [95% CI, 0.88-0.97]; P=0.003). The restricted spline curve depicted a linear and inverse relationship between SBP TTR and incident AF. Sensitivity analyses generated consistent results when calculating TTR over a longer period or setting target range as 110 to 140 mm Hg for the whole population.

CONCLUSIONS

Higher SBP TTR independently predicts a lower risk of incident AF. Efforts to attain SBP within 110 to 140 mm Hg over time may be an effective strategy to prevent AF.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT01206062.

Clinical Profiles and One-Year Outcome in Middle Eastern Patients With Atrial Fibrillation and Hypertension: Analysis From the Jordan Atrial Fibrillation Study

Studies on the impact of hypertension (HTN) on the outcome of patients with atrial fibrillation (AF) in the Middle East are scarce. The aim of this contemporary multicenter study is to evaluate the effect of the coexisting HTN on the baseline clinical profiles and 1-year prognosis in a cohort of Middle Eastern patients with AF. Consecutive AF patients in 29 hospitals and cardiology clinics were enrolled in the Jordan AF study (May 2019-December 2020). Patients were prospectively followed up for 1 year, and the study had no influence on their treatment, which was at the discretion of the treating physician. We compared clinical features, use of medications, and 1-year prognosis in patients with AF/HTN compared with AF/no HTN. Among 1849 non-valvular AF patients, 76.4% had HTN, with higher prevalence of diabetes, dyslipidemia, coronary heart disease, stroke, and left ventricular hypertrophy in HTN patients. There was a higher thromboembolic and bleeding risk among HTN patients. At 1 year, HTN patients had significantly higher rates of stroke and systemic embolism (SSE) (4.5%), acute coronary syndrome (ACS) (2.4%), rehospitalization (27.9%), and major bleeding events (3.0%) compared with non-HTN patients. In this cohort, the coexistence of HTN was associated with worse baseline clinical profile and 1-year outcomes.

Blood pressure, hypertension and the risk of atrial fibrillation: a systematic review and meta-analysis of cohort studies

Elevated blood pressure and hypertension have been associated with increased risk of atrial fibrillation in a number of epidemiological studies, however, the strength of the association has differed between studies. We conducted a systematic review and meta-analysis of the association between blood pressure and hypertension and atrial fibrillation. PubMed and Embase databases were searched for studies of hypertension and blood pressure and atrial fibrillation up to June 6th 2022. Cohort studies reporting adjusted relative risk (RR) estimates and 95% confidence intervals (CIs) of atrial fibrillation associated with hypertension or blood pressure were included. A random effects model was used to estimate summary RRs. Sixty eight cohort studies were included in the meta-analysis. The summary RR was 1.50 (95% CI: 1.42-1.58, I2 = 98.1%, n = 56 studies) for people with hypertension compared to those without hypertension (1,080,611 cases, 30,539,230 participants), 1.18 (95% CI: 1.16-1.21, I2 = 65.9%, n = 37 studies) per 20 mmHg increase in systolic blood pressure (346,471 cases, 14,569,396 participants), and 1.07 (95% CI: 1.03-1.11, I2 = 91.5%, n = 22 studies) per 10 mmHg increase in diastolic blood pressure (332,867 cases, 14,354,980 participants). There was evidence of a nonlinear association between diastolic blood pressure and atrial fibrillation with a steeper increase in risk at lower levels of diastolic blood pressure, but for systolic blood pressure the association appeared to be linear. For both systolic and diastolic blood pressure, the risk increased even within the normal range of blood pressure and persons at the high end of systolic and diastolic blood pressure around 180/110 mmHg had a 1.8-2.3 fold higher risk of atrial fibrillation compared to those with a blood pressure of 90/60 mmHg. These results suggest that elevated blood pressure and hypertension increases the risk of atrial fibrillation and there is some increase in risk even within the normal range of systolic and diastolic blood pressure.

Epidemiology and modifiable risk factors for atrial fibrillation

The global prevalence of atrial fibrillation (AF) has increased substantially over the past three decades and is currently approximately 60 million cases. Incident AF and its clinical consequences are largely the result of risk factors that can be modified by lifestyle changes. In this Review, we provide evidence that the lifetime risk of AF is modified not only by sex and race but also through the clinical risk factor and comorbidity burden of individual patients. We begin by summarizing the epidemiology of AF, focusing on non-modifiable and modifiable risk factors, as well as targets and strategies for the primary prevention of AF. Furthermore, we evaluate the role of modifiable risk factors in the secondary prevention of AF as well as the potential effects of risk factor interventions on the frequency and severity of subsequent AF episodes. We end the Review by proposing strategies that require evaluation as well as global policy changes that are needed for the prevention of incident AF and the management of recurrent episodes in patients already affected by AF.

Associations of maternal gestational diabetes mellitus with alterations in cardiovascular system in early childhood

AIMS

The association of maternal gestational diabetes mellitus (GDM) with childhood cardiovascular alterations is not well established. This study aims to test the hypothesis that prenatal exposure to GDM is associated with vascular and cardiac alterations in early childhood.

METHODS

In a population-based prospective cohort among 1094 mothers and their offspring, GDM was diagnosed according to the International Association of Diabetes and Pregnancy Study Groups criteria. Childhood blood pressure (BP) measurement, echocardiography and vascular ultrasound were performed using standardised methods at 4 years old. The associations between maternal GDM and childhood cardiovascular outcomes were modelled using linear regression and binary logistic regression. Mediation analysis was conducted to test the potential mediators.

RESULTS

Maternal GDM was associated with higher systolic BP (SBP; β, 1.20; [0.11, 2.28]), lower left ventricular end-diastolic diameter (LVEDD; β, -0.36; [-0.71, -0.01]), lower end-diastolic volume (EDV; β, -1.42; [-2.71, -0.13]) and increased risk of high blood pressure (HBP, OR = 1.522; 95% CI, 1.023 to 2.264) in offspring at the age of 4 years. After stratification by sex, the association remained strong only in male offspring (SBP: β, 1.94; [0.37, 3.51]; LVEDD: β, -0.60; [-1.09, -0.12]; EDV: β, -2.09; [-3.86, -0.31]; HBP: OR = 1.797; 95% CI, 1.063 to 3.037) and was independent of maternal and child characteristics. However, carotid intima-media thickness (cIMT) was not associated with maternal GDM. Mediation analysis showed that the effects on childhood cardiovascular alterations were attributable mostly to the direct effects of maternal GDM.

CONCLUSIONS

Our results provide evidence that maternal GDM is associated with offspring cardiovascular adaptations at preschool age. Further studies are needed to replicate our results and the long-term effect of these adaptations on later cardiovascular risks needs further investigation.

Body Mass Index and the Risk of Atrial Fibrillation: A Mendelian Randomization Study

Although observational studies have shown positive associations between body mass index (BMI) and the risk of atrial fibrillation (AF), the causal relationship is still uncertain owing to the susceptibility to confounding and reverse causation. This study aimed to examine the potential causality of BMI on AF by conducting a two-sample Mendelian randomization (TSMR) study.

METHODS

The independent genetic variants associated with BMI (n = 303) at the genome-wide significant level were derived as instrumental variables (IV) from the Genetic Investigation of Anthropometric Traits (GIANT) consortium consisting of 681,275 individuals of European ancestry. We then derived the outcome data from a GWAS meta-analysis comprised of 60,620 cases and 970,216 controls of European ancestry. The TSMR analyses were performed in five methods, namely inverse variance weighted (IVW) method, MR-Egger regression, the weighted median estimator (WME), the generalized summary data-based Mendelian randomization (GSMR), and the robust adjusted profile score (RAPS), to investigate whether BMI was causally associated with the risk of AF.

RESULTS

We found a genetically determined 1-standard deviation (SD) increment of BMI causally increased a 42.5% risk of AF (OR = 1.425; 95% CI, 1.346 to 1.509) based on the IVW method, which was consistent with the results of MR-Egger regression, WME, GSMR, as well as RAPS. The Mendelian randomization assumptions did not seem to be violated.

CONCLUSION

This study provides evidence that higher BMI causally increased the risk of AF, suggesting control of BMI and obesity for prevention of AF.

A phenome-wide bidirectional Mendelian randomization analysis of atrial fibrillation

Background

The prevalence of atrial fibrillation (AF) is increasing with an aging worldwide population, yet a comprehensive understanding of its causes and consequences remains limited. We aim to assess the causes and consequences of AF via a bidirectional Mendelian randomization (MR) analysis.

Methods

We used publicly available genome-wide association study (GWAS) summary data, centralized and harmonized by an open GWAS database. We assessed the genetically predicted effects of 5048 exposures on risk of AF, and the genetically predicted effects of genetic liability to AF, on 10 308 outcomes via two-sample MR analysis. Multivariable MR analysis was further conducted to explore the comparative roles of identified risk factors.

Results

MR analysis suggested that 55 out of 5048 exposure traits, including four proteins, play a causal role in AF (P <1e-5 allowing for multiple comparisons). Multivariable analysis suggested that higher body mass index, height and systolic blood pressure as well as genetic liability to coronary artery diseases independently cause AF. Three out of the four proteins (DUSP13, TNFSF12 and IL6R) had a drug prioritizing score for atrial fibrillation of 0.26, 0.38 and 0.88, respectively (values closer to 1 indicating stronger evidence of the protein as a potential drug target). Genetic liability to AF was linked to a higher risk of cardio-embolic ischaemic stroke.

Conclusions

Our results suggest body mass index, height, systolic blood pressure and genetic liability to coronary artery disease are independent causal risk factors for AF. Several proteins, including DUSP13, IL-6R and TNFSF12, may have therapeutic potential for AF.

Assessment of the Causal Effects of Obstructive Sleep Apnea on Atrial Fibrillation: A Mendelian Randomization Study

Background

Obstructive sleep apnea (OSA) and atrial fibrillation (AF) are epidemiologically correlated, but the causal relationship between them remains elusive. We aimed to explore the causal relationships between OSA and AF.

Method

Using both the Finnish biobank and publicly available genome-wide association study data (GWAS), we conducted a two-sample Mendelian randomization (MR) analysis to estimate the causal effect of OSA on AF, both in the primary analysis and replicated analysis. The inverse variance weighted MR was selected as the main method. To further test the independent causal effect of OSA on AF, we also performed multivariable MR (MVMR), adjusting for body mass index (BMI), hypertension, and coronary artery disease (CAD), respectively.

Results

In the primary analysis, OSA was significantly associated with the increased risk of AF (OR 1.21, 95% CI 1.11–1.32) and the replicated analysis showed consistent results (OR 1.17, 95% CI 1.05–1.30). Besides, there was no heterogeneity and horizontal pleiotropy observed both in the primary and replicated analysis. Further multivariable MR suggested that the causal relationships between OSA and AF exist independently of BMI and CAD. The MVMR result after the adjustment for hypertension is similar in magnitude and direction to the univariable MR. But it did not support a causal relationship between OSA and AF.

Conclusion

Our study found that genetically driven OSA causally promotes AF. This causal relationship sheds new light on taking effective measures to prevent and treat OSA to reduce the risk of AF.

Circulating Vitamin D Levels and the Risk of Atrial Fibrillation: A Two-Sample Mendelian Randomization Study

Aim

We performed a two-sample Mendelian randomization (MR) analysis to evaluate the association between serum vitamin D levels and atrial fibrillation (AF) risks.

Methods

Data on the single-nucleotide polymorphisms (SNPs) related to vitamin D, 25-hydroxyvitamin D, and AF outcome were obtained from a UK Biobank study, SUNLIGHT consortium, and the latest meta-analysis of genome-wide association studies GWASs with six independent cohorts, respectively. MR analysis was performed to obtain the estimates, followed by the use of inverse variance weighted (IVW) method, weighted median method, maximum likelihood, MR-egger method, and MR-PRESSO methods.

Results

The IVW estimate showed that genetically predicted vitamin D and 25-hydroxyvitamin D levels were not causally associated with the risk of AF with two models. The association was consistent in complementary analyses.

Conclusions

Our MR finding suggested that no genetic evidence of serum vitamin D levels was significantly associated with AF risk. Further researches are necessary to explore the potential role and mechanisms of circulating serum vitamin D levels on AF.

The Causal Effects of Lipid Profiles on Sleep Apnea

Introduction

Observational studies have suggested that lipid profiles were associated with risk of sleep apnea (SA). However, the specific lipid types and whether this relationship has a causal effect are uncertain. This study conducted two-sample Mendelian randomization (MR) and multivariable Mendelian randomization (MVMR) to investigate the potential causal relationship between lipid profiles and risk of SA.

Materials and Methods

We used the largest genome-wide association study (GWAS) on European participants on the UK Biobank. After a rigorous single nucleotide polymorphism screening process to remove confounding effects, we performed MR and MVMR to explore the causal relationship between lipid profiles and SA risk.

Results

Both MR and MVMR showed causal effects of increased triglyceride on SA risk [MR: per 10 units, odds ratio (OR): 1.0156; 95% CI: 1.0057-1.0257; P value = 0.002; MVMR: per 10 units, OR: 1.0229; 95% CI: 1.0051-1.0411; P value = 0.011]. The sensitivity analysis including Cochran's Q test, MR-Egger intercept, and MR pleiotropy residual sum and outlier (MR-PRESSO) test indicated that our findings were robust. The causal effects of triglyceride on SA did not change after adjusting for potential confounders (obesity, age, sex, and airway obstruction).

Conclusion

Genetically increased triglyceride levels have independent causal effects on risk of sleep apnea without the confounding effects of obesity, suggesting that lowering triglyceride concentrations may help to reduce the risk of sleep apnea.

Arterial stiffness and atrial fibrillation: A review

Arterial stiffness has been investigated as part of the physiopathology of arterial hypertension since the 1970s. Its role in increasing the "pulsatile load" imposed over the Left Ventricle (LV) has been intensely studied recently and has helped in understanding the mechanisms of Atrial Fibrillation (AF) in hypertensive patients. This paper aims to review the main evidence on this issue and establish possible mechanisms involved in the development of AF in patients with arterial stiffness. A PubMed search was performed, and selected articles were searched for references focusing on this topic. In the long term, lower blood pressure levels allow for arterial wall remodeling, leading to a lower stiffness index. To this day, however, there are no available treatments that directly promote the lowering of arterial wall stiffness. Most classes of anti-hypertensive drugs ‒ with stronger evidence for beta-blockers and diuretics ‒ could be effective in reducing arterial stiffness. There is strong evidence demonstrating an association between arterial stiffness and AF. New studies focusing on arterial stiffness and pre-fibrillatory stages would strengthen this causality relation.

The Relationship between Blood Lipids and Risk of Atrial Fibrillation: Univariable and Multivariable Mendelian Randomization Analysis

We performed univariable and multivariable Mendelian randomization (MR) analysis to evaluate the association between blood lipids and risk of atrial fibrillation (AF), including low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglyceride (TG), Apolipoprotein A1, and Apolipoprotein B.

METHODS

Data on the single nucleotide polymorphisms (SNPs) related to blood lipids were obtained from the UK Biobank study with more than 300,000 subjects of White British European ancestry, and data for AF were from the latest meta-analysis of Genome-wide association study (GWASs) with six independent cohorts with more than 1,000,000 subjects of European ancestry. The univariable MR analysis was conducted to explore whether genetic evidence of individual lipid-related traits was significantly associated with AF risks and multivariable MR analysis with three models was performed to assess the independent effects of lipid-related traits.

RESULTS

The IVW estimate showed that genetically predicted LDL-C (OR: 1.016, 95% CI: 0.962-1.073, p = 0.560), HDL-C (OR: 0.951, 95% CI: 0.895-1.010, p = 0.102), TG (OR: 0.961, 95% CI: 0.889-1.038, p = 0.313), Apolipoprotein A1 (OR: 0.978, 95% CI: 0.933-1.025, p = 0.356), and Apolipoprotein B (OR: 1.008, 95% CI: 0.959-1.070, p = 0.794) were not causally associated with the risk of AF. Sample mode (OR: 0.852, 95% CI: 0.731-0.993, p = 0.043) and weighted mode (OR: 0.907, 95% CI: 0.841-0.979, p = 0.013) showed that a 1-unit increase in TG (mmol/L) was causally associated with a 14.8% and 9.3% relative decrease in AF risk, respectively. The multivariable MR analysis with model 1, 2, and 3 indicated that TG, LDL-C, HDL-C, Apolipoprotein A1, and Apolipoprotein B were not associated with the lower risk for AF.

CONCLUSIONS

Our multivariable Mendelian randomization analysis (MVMR) finding suggested no genetic evidence of lipid traits was significantly associated with AF risk. Furthermore, more work is warranted to confirm the potential association between lipid traits and AF risks.

Association of Autism Spectrum Disorder, Neuroticism, and Subjective Well-Being With Cardiovascular Diseases: A Two-Sample Mendelian Randomization Study

Background: Previous observational studies have reported an association between psychiatric traits and cardiovascular diseases (CVDs). In this two-sample Mendelian randomization (MR) study, we aimed to investigate the causality between psychiatric traits and CVDs.

Methods: Single-nucleotide polymorphisms (SNPs) associated with autism spectrum disorder (ASD), neuroticism, and subjective well-being at genome-wide significance (P < 1 × 10⁻⁸) were identified from genome-wide association studies. Summary-level data of the outcomes, including coronary artery disease (CAD), myocardial infarction (MI), atrial fibrillation (AF), and heart failure (HF), were obtained from several largest datasets. The inverse-variance weighted (IVW) method was used as our main analyses to conduct this MR study. Sensitivity analyses included the weighted median, the MR-robust adjusted profile score (MR-RAPS), and the MR pleiotropy residual sum and outlier (MR-PRESSO) method. Repeated MR analyses using a more relaxed threshold (P < 1 × 10⁻⁶) for instruments selection and multivariable MR analyses were also applied to evaluate the robustness of results.

Results: The MR analyses showed that genetic predisposition to ASD was associated with a higher risk of AF [odds ratio (OR), 1.109; 95% confidence interval (CI), 1.023–1.201; P = 0.011] and HF (OR, 1.138; 95% CI, 1.036–1.251; P = 0.007). Neuroticism was casually associated with an increased risk of AF (OR, 1.201; 95% CI, 1.037–1.392; P = 0.015), whereas subjective well-being had a protective effect on HF (OR, 0.732; 95% CI, 0.574–0.933; P = 0.012). No other causal association between psychiatric traits and CVDs was observed. Consistent results were obtained in sensitivity analyses.

Conclusion: This study provided evidence of causal associations of ASD with a higher risk of AF and HF. Besides, neuroticism was casually associated with an increased risk of AF, and subjective well-being was associated with a decreased risk of HF.