Birth weight influences cardiac structure, function, and disease risk: evidence of a causal association

BACKGROUND AND AIMS

Low birth weight is a common pregnancy complication, which has been associated with higher risk of cardiometabolic disease in later life. Prior Mendelian randomization (MR) studies exploring this question do not distinguish the mechanistic contributions of variants that directly influence birth weight through the foetal genome (direct foetal effects), vs. variants influencing birth weight indirectly by causing an adverse intrauterine environment (indirect maternal effects). In this study, MR was used to assess whether birth weight, independent of intrauterine influences, is associated with cardiovascular disease risk and measures of adverse cardiac structure and function.

METHODS

Uncorrelated (r2 < .001), genome-wide significant (P < 5 × 10-8) single nucleotide polymorphisms were extracted from genome-wide association studies summary statistics for birth weight overall, and after isolating direct foetal effects only. Inverse-variance weighted MR was utilized for analyses on outcomes of atrial fibrillation, coronary artery disease, heart failure, ischaemic stroke, and 16 measures of cardiac structure and function. Multiple comparisons were accounted for by Benjamini-Hochberg correction.

RESULTS

Lower genetically-predicted birth weight, isolating direct foetal effects only, was associated with an increased risk of coronary artery disease (odds ratio 1.21, 95% confidence interval 1.06-1.37; P = .031), smaller chamber volumes, and lower stroke volume, but higher contractility.

CONCLUSIONS

The results of this study support a causal role of low birth weight in cardiovascular disease, even after accounting for the influence of the intrauterine environment. This suggests that individuals with a low birth weight may benefit from early targeted cardiovascular disease prevention strategies, independent of whether this was linked to an adverse intrauterine environment during gestation.

Multiple anthropometric measures and proarrhythmic 12-lead ECG indices: A mendelian randomization study

BACKGROUND

Observational studies suggest that electrocardiogram (ECG) indices might be influenced by obesity and other anthropometric measures, though it is difficult to infer causal relationships based on observational data due to risk of residual confounding. We utilized mendelian randomization (MR) to explore causal relevance of multiple anthropometric measures on P-wave duration (PWD), PR interval, QRS duration, and corrected QT interval (QTc).

METHODS AND FINDINGS

Uncorrelated (r2 < 0.001) genome-wide significant (p < 5 × 10-8) single nucleotide polymorphisms (SNPs) were extracted from genome-wide association studies (GWAS) on body mass index (BMI, n = 806,834), waist:hip ratio adjusted for BMI (aWHR, n = 697,734), height (n = 709,594), weight (n = 360,116), fat mass (n = 354,224), and fat-free mass (n = 354,808). Genetic association estimates for the outcomes were extracted from GWAS on PR interval and QRS duration (n = 180,574), PWD (n = 44,456), and QTc (n = 84,630). Data source GWAS studies were performed between 2018 and 2022 in predominantly European ancestry individuals. Inverse-variance weighted MR was used for primary analysis; weighted median MR and MR-Egger were used as sensitivity analyses. Higher genetically predicted BMI was associated with longer PWD (β 5.58; 95%CI [3.66,7.50]; p = < 0.001), as was higher fat mass (β 6.62; 95%CI [4.63,8.62]; p < 0.001), fat-free mass (β 9.16; 95%CI [6.85,11.47]; p < 0.001) height (β 4.23; 95%CI [3.16, 5.31]; p < 0.001), and weight (β 8.08; 95%CI [6.19,9.96]; p < 0.001). Finally, genetically predicted BMI was associated with longer QTc (β 3.53; 95%CI [2.63,4.43]; p < 0.001), driven by both fat mass (β 3.65; 95%CI [2.73,4.57]; p < 0.001) and fat-free mass (β 2.08; 95%CI [0.85,3.31]; p = 0.001). Additionally, genetically predicted height (β 0.98; 95%CI [0.46,1.50]; p < 0.001), weight (β 3.45; 95%CI [2.54,4.36]; p < 0.001), and aWHR (β 1.92; 95%CI [0.87,2.97]; p = < 0.001) were all associated with longer QTc. The key limitation is that due to insufficient power, we were not able to explore whether a single anthropometric measure is the primary driver of the associations observed.

CONCLUSIONS

The results of this study support a causal role of BMI on multiple ECG indices that have previously been associated with atrial and ventricular arrhythmic risk. Importantly, the results identify a role of both fat mass, fat-free mass, and height in this association.

Bariatric Surgery and Incident Heart Failure: a Propensity Score Matched Nationwide Cohort Study

BACKGROUND

Bariatric surgery results in significant weight loss and a reduction in the incidence of cardiovascular disease in patients with obesity; however, relatively little research considers its effect on the incidence of heart failure (HF). We aimed to determine whether bariatric surgery reduces the incidence of HF in patients with obesity, compared to non-surgical management.

METHODS

A propensity-score matched, retrospective cohort study using patients records from the nationwide Clinical Practice Research Database (CPRD) was conducted. 3052 patients who received bariatric surgery were matched with 3052 patients who did not, according to propensity to receive bariatric surgery, determined through a logistic regression model. Patients were eligible if >18 years old, BMI > 35 kg/m², and no prior diagnosis of HF. The pre-defined primary endpoint was the development of new HF, and secondary endpoints were all-cause mortality and hospitalisations due to HF.

RESULTS

Patients who received bariatric surgery had a significantly lower incidence of new HF (hazard ratio 0.45, 95% confidence interval 0.28-0.73, p = 0.0011) and all-cause mortality (hazard ratio 0.56, 95% confidence interval 0.38-0.83, p = 0.0036).

CONCLUSIONS

This study provides evidence of lower rates of HF and all-cause mortality in patients who undergo bariatric surgery, compared to propensity-score matched controls. Future studies to understand the mechanism(s) involved in this reduction and explore the lifetime benefits in high-risk cohorts are paramount.

Association of Hypertensive Disorders of Pregnancy With Future Cardiovascular Disease

CONCLUSIONS AND RELEVANCE

The findings of this study provide genetic evidence supporting an association between HDPs and higher risk of coronary artery disease and stroke, which is only partially mediated by cardiometabolic factors. This supports classification of HDPs as risk factors for cardiovascular disease.

DESIGN, SETTING, AND PARTICIPANTS

A genome-wide genetic association study using mendelian randomization (MR) was performed from February 16 to March 4, 2022. Primary analysis was conducted using inverse-variance-weighted MR. Mediation analyses were performed using a multivariable MR framework. All studies included patients predominantly of European ancestry. Female-specific summary-level data from FinnGen (sixth release).

EXPOSURES

Uncorrelated (r2<0.001) single-nucleotide variants (SNVs) were selected as instrumental variants from the FinnGen consortium summary statistics for exposures of any HDP, gestational hypertension, and preeclampsia or eclampsia.

IMPORTANCE

Hypertensive disorders in pregnancy (HDPs) are major causes of maternal and fetal morbidity and are observationally associated with future maternal risk of cardiovascular disease. However, observational results may be subject to residual confounding and bias.

MAIN OUTCOMES AND MEASURES

Genetic association estimates for outcomes were extracted from genome-wide association studies of 122 733 cases for coronary artery disease, 34 217 cases for ischemic stroke, 47 309 cases for heart failure, and 60 620 cases for atrial fibrillation.

OBJECTIVE

To investigate the association of HDPs with multiple cardiovascular diseases.

RESULTS

Genetically predicted HDPs were associated with a higher risk of coronary artery disease (odds ratio [OR], 1.24; 95% CI, 1.08-1.43; P = .002); this association was evident for both gestational hypertension (OR, 1.08; 95% CI, 1.00-1.17; P = .04) and preeclampsia/eclampsia (OR, 1.06; 95% CI, 1.01-1.12; P = .03). Genetically predicted HDPs were also associated with a higher risk of ischemic stroke (OR, 1.27; 95% CI, 1.12-1.44; P = 2.87 × 10-4). Mediation analysis revealed a partial attenuation of the effect of HDPs on coronary artery disease after adjustment for systolic blood pressure (total effect OR, 1.24; direct effect OR, 1.10; 95% CI, 1.02-1.08; P = .02) and type 2 diabetes (total effect OR, 1.24; direct effect OR, 1.16; 95% CI, 1.04-1.29; P = .008). No associations were noted between genetically predicted HDPs and heart failure (OR, 0.97; 95% CI, 0.76-1.23; P = .79) or atrial fibrillation (OR, 1.11; 95% CI, 0.65-1.88; P = .71).

Hypertensive disorders in pregnancy increase subsequent risk of ischaemic cardiovascular events: genetic evidence from a Mendelian randomisation study

Background

Hypertensive disorders in pregnancy are major causes of maternal and foetal morbidity and have also been associated with long-term maternal risk of cardiovascular diseases. Whilst many retrospective and prospective cohort studies have explored this relationship, it is difficult to make causal inferences from observational studies due to potential residual confounding and bias. Leveraging genetic data predisposing to exposures and outcomes in instrumental variable analysis, Mendelian randomisation (MR) can provide valuable information for causal inference. The aim of this study is to use MR to investigate the relationship between hypertensive disorders in pregnancy and cardiovascular diseases.

Methods

Uncorrelated single nucleotide polymorphisms (SNPs) were selected as instrumental variables from the FinnGen consortium summary statistics for the exposures of any hypertensive disorder in pregnancy, and its two subgroups of gestational hypertension, and pre-eclampsia or eclampsia. Genetic association estimates for outcomes were extracted from GWAS studies of 122,733 for coronary artery disease, 34,217 cases for ischaemic stroke, 47,309 cases for heart failure and 60,620 cases for atrial fibrillation. All studies included patients predominantly of European ancestry. Primary analysis was conducted using inverse-variance weighted MR.

Results

Hypertensive disorders in pregnancy were associated with increased risk of coronary artery disease (odds ratio (OR) 1.24; 95% confidence interval (CI) 1.08–1.43; p=0.002); and this association was evident for both gestational hypertension (OR= 1.08; 95% CI: 1.00–1.17; p=0.040) and pre- or eclampsia (OR=1.06; 95% CI: 1.01–1.12; p=0.030). Hypertensive disorders in pregnancy were also associated with increased risk of ischaemic stroke (OR=1.27; 95% CI: 1.12–1.44; p=2.87x10–4). Neither gestational hypertension nor pre-eclampsia were independently associated with increased risk of ischaemic stroke, though effect estimates were consistent in direction. No associations were noted between the three hypertensive disorders in pregnancy and the outcomes of heart failure or atrial fibrillation.

Conclusions

Our findings provide genetic evidence that supports a likely causal association between hypertension in pregnancy and increased risk of coronary artery disease and stroke. This is consistent with observational evidence and supports the classification of hypertensive disorders in pregnancy as risk factors for cardiovascular disease.

Funding Acknowledgement

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Research Council GEPSI 946647 for EAWSBritish Heart Foundation RG/16/3/32175 for FSN

The Impact and Management of Gynaecomastia in Klinefelter Syndrome

Gynecomastia is defined as a palpable enlargement of the male breast, secondary to an increase in the glandular and stromal breast tissue. Gynecomastia is encountered in up to 80% of Klinefelter syndrome cases. The pathophysiology involves testosterone/estrogen imbalance. This review article will further explore the pathophysiology of gynecomastia along with the different lines of management.