Repeated measurements of carotid atherosclerosis and future risk of venous thromboembolism: the Tromsø Study

Mendelian Randomization Study Does Not Support a Bidirectional Link between Atherosclerosis and Venous Thromboembolism

AIM

Some observational studies suggested that atherosclerosis increased the risk of venous thromboembolism (VTE), and vice versa. However, the results were conflicting, and the causal relationship is yet to be established. Therefore, we applied Mendelian randomization (MR) analyses to assess the bidirectional causality between coronary heart disease (CHD) and VTE, deep venous thrombosis (DVT), and pulmonary embolism (PE).

METHODS

A total of 184,305 individuals with CHD were included from the CARDIoGRAMplusC4D Consortium. Information on VTE, DVT, and PE were obtained from the FinnGen biobank. Genetic instruments for CHD and VTE were constructed using 37 and 12 single-nucleotide polymorphisms, respectively. Inverse-variance weighted meta-analysis under a random-effect model was used as the preliminary estimate. Five complementary MR methods were also used, including weighted median, MR-Egger, multivariable MR (adjusted for the body mass index), simple mode, and weighted mode methods.

RESULTS

The genetically instrumented VTE (odds ratio [OR]: 1.05; 95% confidence interval [CI]: 1.00-1.11; P=0.06), DVT (OR: 1.03; 95% CI: 0.99-1.08; P=0.19), or PE (OR: 1.07; 95% CI: 0.98-1.16; P=0.11) showed no causal relationships with CHD. There was also no clear evidence showing the causal effects of CHD on VTE (OR: 1.00; 95% CI: 0.82-1.22; P=0.98), DVT (OR: 1.00; 95% CI: 0.79-1.27; P=0.97), or PE (OR: 0.98; 95% CI: 0.82-1.18; P=0.87). No pleiotropic bias was found in the MR analyses. As heterogeneity was significant, a random model was used to minimize the effect of heterogeneity.

CONCLUSIONS

No causal associations existed between CHD and VTE. Arterial and venous thromboses may represent separate entities.

Joint effect of myocardial infarction and obesity on the risk of venous thromboembolism: The Tromsø Study

BACKGROUND

Myocardial infarction (MI) is associated with an increased risk of venous thromboembolism (VTE). Obesity is a recognized risk factor for both MI and VTE. Whether obesity further increases the risk of VTE in MI patients is scarcely investigated.

AIM

To study the joint effect of MI and obesity on the risk of VTE.

METHODS

Study participants (n = 29 410) were recruited from three surveys of the Tromsø Study (conducted in 1994-1995, 2001, and 2007-2008) and followed up through 2014. All incident MI and VTE cases during follow-up were recorded. Cox regression models with MI as a time-dependent variable were used to estimate hazard ratios (HRs) of VTE (adjusted for age and sex) by combinations of MI exposure and obesity status. Joint effects were assessed by calculating relative excess risk and attributable proportion (AP) due to interaction.

RESULTS

During a median of 19.6 years of follow-up, 2090 study participants experienced an MI and 784 experienced a VTE. Among those with MI, 55 developed a subsequent VTE, yielding an overall incidence rate (IR) of VTE of 5.3 per 1000 person-years (95% confidence interval [CI]: 4.1-6.9). In the combined exposure group (MI+/Obesity+), the IR was 11.3 per 1000 person-years, and the adjusted HR indicated a 3-fold increased risk of VTE (HR 3.16, 95% CI: 1.99-4.99) compared to the reference group (MI-/Obesity-). The corresponding AP was 0.46 (95% CI: 0.17-0.74).

CONCLUSIONS

The combination of MI and obesity yielded a supra-additive effect on VTE risk of which 46% of the VTE events were attributed to the interaction.

No prospective association of a polygenic risk score for coronary artery disease with venous thromboembolism incidence

BACKGROUND

Previous studies are inconsistent about whether chronic coronary artery disease or generalized atherosclerosis is a causal risk factor for venous thromboembolism. No study seems to have taken a genomic approach to this question.

OBJECTIVE

To test in a prospective study whether a polygenic risk score for coronary artery disease is associated with risk of venous thromboembolism.

PARTICIPANTS/METHODS

Within the Atherosclerosis Risk in Communities Study cohort, we computed a previously validated polygenic risk score for coronary artery disease among 9144 White participants at baseline in 1987-1989. We followed the participants through 2015 for incident hospitalized venous thromboembolism events, validated by physician review. We used Cox proportional hazards regression to associate quintiles of the polygenic risk score to venous thromboembolism incidence rates.

RESULTS

Over the median of 26 years of follow-up, 476 participants had a venous thromboembolism event. There was no apparent association between the coronary artery disease polygenic risk score and incident venous thromboembolism, with age, sex, body mass index adjusted hazard ratios across quintiles being 1 (reference), 0.87 (0.65, 1.15), 1.08 (0.82, 1.42), 0.96 (0.72, 1.27), and 1.03 (0.78, 1.37).

CONCLUSIONS

A genetic disposition to coronary artery disease did not confer an increased risk of venous thromboembolism in this prospective study.

Effects of deferred versus immediate stenting on left ventricular function in patients with ST elevation myocardial infarction

BACKGROUND

Previous studies have shown conflicting results on the benefits of deferred stenting (DS) in infarct size and the incidence of microvascular obstruction in patients with ST elevation myocardial infarction (STEMI). However, effect of DS on left ventricular (LV) function was not known. We aimed to evaluate whether DS improve LV function and relevant clinical outcomes after STEMI, using follow-up data from the INNOVATION study (NCT02324348).

METHODS

In total, 114 patients were randomly assigned to DS group or immediate stenting (IS) group at a 1:1 ratio. LV functional remodeling indices and MACE (major adverse cardiac events: a composite of death, non-fatal MI, unplanned target vessel revascularization, or hospitalization due to heart failure) were compared between DS and IS groups.

RESULTS

Serial echocardiographic analyses were completed in 89 subjects (78%). There were no significant changes in LV volume in either group. While LV ejection fraction and wall motion score index (WMSI) improved in both groups during follow-up, the increments were not statistically different between the 2 groups (4.3 ± 8.2 vs 3.2 ± 7.1, P = .504 for ΔLV ejection fraction; -0.16 ± 0.25 vs -0.16 ± 0.25, P = .99 for ΔWMSI). However, E/e'' was decreased and e' was increased only in the DS group (-3.31 ± 5.60 vs -0.46 ± 3.10, P = .005 for ΔE/e'; 0.77 ± 1.71 vs -0.22 ± 1.64, P = .009 for Δe'). The incidence of major adverse cardiac events was numerically lower in the DS group than in the IS group without a statistical significance at 1-year follow-up.

CONCLUSIONS

Routine DS improved LV diastolic function but not systolic function compared with IS in patients with STEMI.

Myocardial infarction, prothrombotic genotypes, and venous thrombosis risk: The Tromsø Study

BACKGROUND

The risk of venous thromboembolism (VTE) is increased after a myocardial infarction (MI). Some prothrombotic genotypes associated with VTE have also been associated with risk of MI. Whether prothrombotic single-nucleotide polymorphisms (SNPs) further increase the risk of VTE in MI patients is scarcely investigated.

AIM

To study the combined effect of MI and prothrombotic SNPs on the risk of VTE.

METHODS

Cases with incident VTE (n = 641) and a randomly sampled subcohort weighted for age (n = 1761) were identified from the 4 to 6 surveys of the Tromsø Study (1994-2012). DNA was genotyped for rs8176719 (ABO), rs6025 (F5), rs1799963 (F2), rs2066865 (FGG), and rs2036914 (F11). Hazard ratios (HRs) for VTE with 95% confidence intervals (CIs) were estimated by categories of risk alleles and MI status.

RESULTS

Patients with MI had a 1.4-fold increased risk of VTE, and adjustments for the 5 SNPs, either alone or in combination, did not affect this relationship (adjusted HR, 1.52; 95% CI, 1.12-2.07). In subjects without MI, an increased risk of VTE was observed for each of the individual SNPs (≥1 vs. 0 risk alleles), and the risk increased linearly with increasing number of risk alleles in the 5-SNP score. The combination of MI and prothrombotic genotypes, either as individual SNPs or in the 5-SNP score, did not result in an excess risk of VTE.

CONCLUSION

The relationship between MI and VTE was not explained by these 5 prothrombotic genotypes. Prothrombotic genotypes did not yield an excess risk of VTE in patients with MI.

Is there a link between venous and arterial thrombosis? A reappraisal

Whether there is a link between venous and arterial thrombotic disorders is still a matter of debate. They share common risk factors, such as old age, male sex and obesity. Endothelial dysfunction and inflammation are likely to play a role in determining the simultaneous involvement of the two vascular compartments. Unlike subclinical atherosclerosis, symptomatic complications of atherosclerosis such as myocardial infarction, ischemic stroke and atrial fibrillation are likely to predict the subsequent development of venous thromboembolic (VTE) complications. Patients with VTE, especially those with apparently unprovoked episodes, have a definitely increased risk of subsequent arterial thrombotic disorders. Drugs that reduce the risk of arterial thrombosis are likely to reduce the risk of venous thrombosis and vice versa. In particular, the direct oral anticoagulants have recently been shown to reduce the risk of both vascular disorders. In conclusion, recent evidence provides compelling evidence in support of the link between venous and arterial thrombosis. Future studies are needed to clarify the nature of this association, to assess its extent, and to evaluate its implications for clinical practice.