Genetic Characteristics of Latvian Patients with Familial Hypercholesterolemia: The First Analysis from Genome-Wide Sequencing

BACKGROUND

There is limited data on the genetic characteristics of patients with familial hypercholesterolemia (FH) in Latvia. We aim to describe monogenic variants in patients from the Latvian Registry of FH (LRFH).

METHODS

Whole genome sequencing with 30× coverage was performed in unrelated index cases from the LRFH and the Genome Database of Latvian Population. LDLR, APOB, PCSK9, LDLRAP1, ABCG5, ABCG8, LIPA, LPA, CYP27A1, and APOE genes were analyzed. Only variants annotated as pathogenic (P) or likely pathogenic (LP) using the FH Variant Curation Expert Panel guidelines for LDLR and adaptations for APOB and PCSK9 were reported.

RESULTS

Among 163 patients, the mean highest documented LDL-cholesterol level was 7.47 ± 1.60 mmol/L, and 79.1% of patients had LDL-cholesterol ≥6.50 mmol/L. A total of 15 P/LP variants were found in 34 patients (diagnostic yield: 20.9%): 14 in the LDLR gene and 1 in the APOB gene. Additionally, 24, 54, and 13 VUS were detected in LDLR, APOB, and PCSK9, respectively. No P/LP variants were identified in the other tested genes.

CONCLUSIONS

Despite the high clinical likelihood of FH, confirmed P/LP variants were detected in only 20.9% of patients in the Latvian cohort when assessed with genome-wide next generation sequencing.

A case report of pulmonary vein isolation performed in a patient with polysplenia and interrupted inferior vena cava

Background

Pulmonary vein isolation (PVI) has entrenched itself as one of the main approaches for the treatment of paroxysmal symptomatic atrial fibrillation (AF). Pulmonary vein isolation prevents focal triggers from pulmonary veins from initiating AF paroxysms. As standard—PVI is performed through the inferior vena cava (IVC) approach, through the femoral vein. However, there are conditions when this approach is not appropriate or is not available.

Case summary

We report a case of a 53-year-old male who was referred to Pauls Stradins Clinical University Hospital for PVI due to worsening AF. Due to the rare anatomical variant of the venous system, the standard approach to PVI could not be applied. Interrupted cava inferior did not allow for femoral vein and IVC access. We had to figure out a different path—a combination of internal jugular and subclavian veins was used. Transseptal puncture was performed under transoesophageal echocardiography (TOE) control with a puncture needle stiletto. Pulmonary veins were isolated successfully, no complications were observed, and the patient was discharged in sinus rhythm.

Discussion

In some patients, PVI cannot be done through the standard IVC approach. In such cases, a different venous access must be chosen. Our patient had a rare variant of interrupted IVC and we had to use superior vena cava approach for the procedure. The difficulty of this approach is that procedure instruments are not designed for non-standard venous access; however, a combined use of TOE, general anaesthesia, and contact force-guided ablation has succeeded in isolating patients’ pulmonary veins.

Global perspective of familial hypercholesterolaemia: a cross-sectional study from the EAS Familial Hypercholesterolaemia Studies Collaboration (FHSC)

BACKGROUND

The European Atherosclerosis Society Familial Hypercholesterolaemia Studies Collaboration (FHSC) global registry provides a platform for the global surveillance of familial hypercholesterolaemia through harmonisation and pooling of multinational data. In this study, we aimed to characterise the adult population with heterozygous familial hypercholesterolaemia and described how it is detected and managed globally.

METHODS

Using FHSC global registry data, we did a cross-sectional assessment of adults (aged 18 years or older) with a clinical or genetic diagnosis of probable or definite heterozygous familial hypercholesterolaemia at the time they were entered into the registries. Data were assessed overall and by WHO regions, sex, and index versus non-index cases.

FINDINGS

Of the 61 612 individuals in the registry, 42 167 adults (21 999 [53·6%] women) from 56 countries were included in the study. Of these, 31 798 (75·4%) were diagnosed with the Dutch Lipid Clinic Network criteria, and 35 490 (84·2%) were from the WHO region of Europe. Median age of participants at entry in the registry was 46·2 years (IQR 34·3-58·0); median age at diagnosis of familial hypercholesterolaemia was 44·4 years (32·5-56·5), with 40·2% of participants younger than 40 years when diagnosed. Prevalence of cardiovascular risk factors increased progressively with age and varied by WHO region. Prevalence of coronary disease was 17·4% (2·1% for stroke and 5·2% for peripheral artery disease), increasing with concentrations of untreated LDL cholesterol, and was about two times lower in women than in men. Among patients receiving lipid-lowering medications, 16 803 (81·1%) were receiving statins and 3691 (21·2%) were on combination therapy, with greater use of more potent lipid-lowering medication in men than in women. Median LDL cholesterol was 5·43 mmol/L (IQR 4·32-6·72) among patients not taking lipid-lowering medications and 4·23 mmol/L (3·20-5·66) among those taking them. Among patients taking lipid-lowering medications, 2·7% had LDL cholesterol lower than 1·8 mmol/L; the use of combination therapy, particularly with three drugs and with proprotein convertase subtilisin-kexin type 9 inhibitors, was associated with a higher proportion and greater odds of having LDL cholesterol lower than 1·8 mmol/L. Compared with index cases, patients who were non-index cases were younger, with lower LDL cholesterol and lower prevalence of cardiovascular risk factors and cardiovascular diseases (all p<0·001).

INTERPRETATION

Familial hypercholesterolaemia is diagnosed late. Guideline-recommended LDL cholesterol concentrations are infrequently achieved with single-drug therapy. Cardiovascular risk factors and presence of coronary disease were lower among non-index cases, who were diagnosed earlier. Earlier detection and greater use of combination therapies are required to reduce the global burden of familial hypercholesterolaemia.

FUNDING

Pfizer, Amgen, Merck Sharp & Dohme, Sanofi-Aventis, Daiichi Sankyo, and Regeneron.

Lead-Related Infective Endocarditis in Latvia: A Single Centre Experience

Background and Objectives: Over the last five decades cardiac implantable electronic devices (CIED) have become established as the mainstay for the treatment of permanent bradycardias, chronic heart failure and dangerous heart rhythm disturbances. These devices improve survival and quality of life in many patients. However, infections associated with CIED implantation, particularly lead-related infective endocarditis (LRIE), can offset all benefits and make more harm than good for the patient. To date, there are no other studies in Latvia, addressing patients with lead-related infective endocarditis. The objective of this study was to identify the most common pathogens associated with LRIE and their antimicrobial resistance and to identify possible risk factors of patients who present with LRIE. Materials and Methods: The study was performed retrospectively at Pauls Stradins Clinical University Hospital (PSCUH). The study included patients who were referred to PSCUH due to LRIE for lead extraction. Patients were identified from procedural journals. Information about isolated microorganisms, patient comorbidities and visual diagnostics data was taken from patient records. Results: Forty-nine patients with CIED related infective endocarditis were included in the study, 34 (69.4%) were male, median age of all patients was 65.0 (50.5-73.0) years, median hospital stay was 15.5 (22.0-30.5) days. Successful and complete lead extraction was achieved in all patients. Thirty-two (65.3%) had received antibiotics prior to blood sample. Only in 31 (63.3%) positive culture results were seen. The most common isolated pathogens were Staphylococcus aureus (23.5%) and coagulase negative staphylococci (23.5%). Other bacteria were isolated considerably less often. The atrial lead was most common location for lead vegetations, seen in 50.0% of cases. Five (10.2%) patients have died due to the disease. Conclusions: Lead-related infective endocarditis is a major complication of cardiac implantable electronic devices with considerable morbidity and mortality, which in our study was as high as 10.2%.