REduction of THRomboembolic EVents during Ablation using the laserballoon: The RETHREVA registry.

INTRODUCTION: Cerebral events (CEs), including silent (SCEs), are a known complication of left atrial catheter ablation (LACA) in patients with atrial fibrillation. The aim of this prospective registry was to gain more information about CEs during laserballoon LACA and to reduce the risk of their occurrence. METHODS AND RESULTS: We enrolled 74 patients (age 61 ± 11 years; 74% male; CHA2 DS2 -VASc 1.9 ± 1.4). Cerebral MRI (1.5 Tesla) was performed to detect CEs. ASPItest identified aspirin-resistant patients (ARPs). All bleeding complications were recorded. Due to an initial high CE rate, we evolved our clinical procedure step-by-step arriving at an optimized protocol: -Group 1: heparin after single transseptal puncture (TP), activated clotting time (ACT) > 300 seconds (CE: 64.3%). -Group 2: heparin after double TP, ACT > 300 seconds; 2a without (CE: 45.5%, RRR: -29.2%) and 2b with additional intravenous aspirin (CE: 36.4%, RRR: -43.4%; excluding ARP: 30%, RRR: -53.3%). -Group 3: heparin before double TP, ACT > 350 seconds; 3a without (CE: 54.5%, RRR: -15.2%) and 3b with aspirin (CE: 18.5%, RRR: -71.2%; excluding ARP: 8.7%, RRR: -86.5%). Larger LA diameter > 44 mm (OR: 1.149, P  =  0.005) and no aspirin use (OR: 4.308, P  =  0.008) were CE risk factors in multivariate logistic regression. In those patients receiving aspirin, aspirin resistance (OR: 22.4, P  =  0.011) was an exceptionally strong risk factor. CONCLUSION: These data support the use of intravenous aspirin including monitoring of aspirin resistance in addition to ACT-guided heparin. An optimized protocol of heparin before TP, double TP, and intravenous aspirin in non-ARP resulted in a significantly lowered CE incidence and severity.

Candidate gene variants of the immune system and sudden infant death syndrome.

BACKGROUND: Sudden infant death syndrome (SIDS) causes early infant death with an incidence between 0.5 and 2.5 cases among 1000 live births. Besides central sleep apnea and thermal dysregulation, infections have been repeatedly suggested to be implicated in SIDS etiology. METHODS: To test the risk contribution of common genetic variants related to infection, we genotyped 40 single-nucleotide polymorphisms (SNPs) from 15 candidate genes for association with SIDS in a total of 579 cases and 1124 controls from Germany and the UK in a two-stage case control design. RESULTS: The discovery-stage series (267 SIDS cases and 303 controls) revealed nominally significant associations for variants in interleukin 6 (IL6) (rs1880243), interleukin 10 (IL10) (rs1800871, rs1800872), and mannose-binding lectin 2 (MBL2) (rs930506), and for several other variants in subgroups. Meta-analyses were then performed in adding genotype information from a genome-wide association study of another 312 European SIDS cases and 821 controls. Overall associations were observed for two independent variants in MBL2: rs930506 in a co-dominant model (odds ratio (OR) = 0.82, p = 0.04) and rs1838065 in a dominant model (OR = 1.27, p = 0.03). CONCLUSION: Our study did not replicate published associations of IL10 variants with SIDS. However, the evidence for two independent MBL2 variants in the combined analysis of two large series seems consistent with the hypothesis that infection may play a role in SIDS pathogenesis.

The cost-effectiveness of UGT1A1 genotyping before colorectal cancer treatment with irinotecan from the perspective of the German statutory health insurance.

BACKGROUND: The evidence concerning the cost-effectiveness of UGT1A1*28 genotyping is ambiguous and does not allow drawing valid conclusions for Germany. This study evaluates the cost-effectiveness of UGT1A1 genotyping in patients with metastatic colorectal cancer undergoing irinotecan-based chemotherapy compared to no testing from the perspective of the German statutory health insurance. MATERIAL AND METHODS: A decision-analytic Markov model with a life time horizon was developed. No testing was compared to two genotype-dependent therapy strategies: 1) dose reduction by 25%; and 2) administration of a prophylactic G-CSF growth factor analog for homozygous and heterozygous patients. Probability, quality of life and cost parameters used in this study were based on published literature. Deterministic and probabilistic sensitivity analyses were performed to account for parameter uncertainties. RESULTS: Strategy 1 dominated all remaining strategies. Compared to no testing, it resulted in only marginal QALY increases (0.0002) but a cost reduction of €580 per patient. Strategy 2 resulted in the same health gains but increased costs by €10 773. In the probabilistic analysis, genotyping and dose reduction was the optimal strategy in approximately 100% of simulations at a threshold of €50 000 per QALY. Deterministic sensitivity analysis shows that uncertainty for this strategy originated primarily from costs for irinotecan-based chemotherapy, from the prevalence of neutropenia among heterozygous patients, and from whether dose reduction is applied to both homozygotes and heterozygotes or only to the former. CONCLUSION: This model-based synthesis of the most recent evidence suggests that pharmacogenetic UGT1A1 testing prior to irinotecan-based chemotherapy dominates non-personalized colon cancer care in Germany. However, as structural uncertainty remains high, these results require validation in clinical practice, e.g. based on a managed-entry agreement.

Inherited cardiac arrhythmias: diagnosis, treatment, and prevention.

BACKGROUND: The incidence of sudden cardiac death in persons under age 40 is roughly 3 per 100 000 persons per year in Germany and North America. Many of these deaths are found to be due to hereditary heart diseases, often a primary structural heart disease associated with arrhythmia or else a primary arrhythmia syndrome in a structurally normal heart. Such diseases are usually of autosomal dominant inheritance, often affect otherwise healthy persons, and can generally be well treated if recognized early. Patients commonly have affected relatives who are still asymptomatic. METHODS: This review is based on articles up to May 2010 that were retrieved by a selective search of the Medline database via PubMed, with additional consideration of the relevant European and American guidelines and the German Law on Genetic Diagnosis. RESULTS AND CONCLUSION: Hereditary arrhythmia syndromes are now found in more than half of all initially unexplained cases of sudden cardiac death in young persons. Among such cases, the hereditary arrhythmia syndrome is primary in 70% and caused by an arrhythmogenic structural heart disease in 30%. In addition to autopsy findings, a thorough family history, relevant medical findings obtained during life (if available), the examination of relatives, and directed molecular testing where appropiate enabled establishing the diagnosis. Arrthymia syndromes that can cause sudden death are often detectable during life if physicians and the public are appropriately sensitized.

Genome-wide association studies of the PR interval in African Americans.

The PR interval on the electrocardiogram reflects atrial and atrioventricular nodal conduction time. The PR interval is heritable, provides important information about arrhythmia risk, and has been suggested to differ among human races. Genome-wide association (GWA) studies have identified common genetic determinants of the PR interval in individuals of European and Asian ancestry, but there is a general paucity of GWA studies in individuals of African ancestry. We performed GWA studies in African American individuals from four cohorts (n = 6,247) to identify genetic variants associated with PR interval duration. Genotyping was performed using the Affymetrix 6.0 microarray. Imputation was performed for 2.8 million single nucleotide polymorphisms (SNPs) using combined YRI and CEU HapMap phase II panels. We observed a strong signal (rs3922844) within the gene encoding the cardiac sodium channel (SCN5A) with genome-wide significant association (p<2.5 x 10⁻8) in two of the four cohorts and in the meta-analysis. The signal explained 2% of PR interval variability in African Americans (beta  = 5.1 msec per minor allele, 95% CI  = 4.1-6.1, p = 3 x 10⁻²³). This SNP was also associated with PR interval (beta = 2.4 msec per minor allele, 95% CI = 1.8-3.0, p = 3 x 10⁻¹6) in individuals of European ancestry (n = 14,042), but with a smaller effect size (p for heterogeneity <0.001) and variability explained (0.5%). Further meta-analysis of the four cohorts identified genome-wide significant associations with SNPs in SCN10A (rs6798015), MEIS1 (rs10865355), and TBX5 (rs7312625) that were highly correlated with SNPs identified in European and Asian GWA studies. African ancestry was associated with increased PR duration (13.3 msec, p = 0.009) in one but not the other three cohorts. Our findings demonstrate the relevance of common variants to African Americans at four loci previously associated with PR interval in European and Asian samples and identify an association signal at one of these loci that is more strongly associated with PR interval in African Americans than in Europeans.

Common variants in 22 loci are associated with QRS duration and cardiac ventricular conduction.

The QRS interval, from the beginning of the Q wave to the end of the S wave on an electrocardiogram, reflects ventricular depolarization and conduction time and is a risk factor for mortality, sudden death and heart failure. We performed a genome-wide association meta-analysis in 40,407 individuals of European descent from 14 studies, with further genotyping in 7,170 additional Europeans, and we identified 22 loci associated with QRS duration (P < 5 × 10(-8)). These loci map in or near genes in pathways with established roles in ventricular conduction such as sodium channels, transcription factors and calcium-handling proteins, but also point to previously unidentified biologic processes, such as kinase inhibitors and genes related to tumorigenesis. We demonstrate that SCN10A, a candidate gene at the most significantly associated locus in this study, is expressed in the mouse ventricular conduction system, and treatment with a selective SCN10A blocker prolongs QRS duration. These findings extend our current knowledge of ventricular depolarization and conduction.

Variation in the 4q25 chromosomal locus predicts atrial fibrillation after coronary artery bypass graft surgery.

BACKGROUND: Atrial fibrillation (AF) is the most common adverse event following coronary artery bypass graft surgery. A recent study identified chromosome 4q25 variants associated with AF in ambulatory populations. However, their role in postoperative AF is unknown. We hypothesized that genetic variants in the 4q25 chromosomal region are independently associated with postoperative AF after coronary artery bypass graft surgery. METHODS AND RESULTS: Two prospectively collected cohorts of patients undergoing coronary artery bypass graft surgery, with or without concurrent valve surgery, at 3 US centers. From a discovery cohort of 959 patients, clinical and genomic multivariate predictors of postoperative AF were identified by genotyping 45 single-nucleotide polymorphisms (SNPs) encompassing the 4q25 locus. Three SNPs were then assessed in a separately collected validation cohort of 494 patients. After adjustment for clinical predictors of postoperative AF and multiple comparisons, rs2200733, rs13143308, and 5 other linked SNPs independently predicted postoperative AF in the discovery cohort. Additive odds ratios for the 7 associated 4q25 SNPs ranged between 1.57 and 2.17 (P=8.0x10(-4) to 3.4x10(-6)). Association with postoperative AF were measured and replicated for rs2200733 and rs13143308 in the validation cohort. CONCLUSIONS: In 2 independently collected cardiac surgery cohorts, noncoding SNPs within the chromosome 4q25 region are independently associated with postoperative AF after coronary artery bypass graft surgery after adjusting for clinical covariates and multiple comparisons.

Positive selection at codon 38 of the human KCNE1 (= minK) gene and sporadic absence of 38Ser-coding mRNAs in Gly38Ser heterozygotes.

BACKGROUND: KCNE1 represents the regulatory beta-subunit of the slowly activating delayed rectifier potassium channel (IKs). Variants of KCNE1 have repeatedly been linked to the long-QT syndrome (LQTS), a disorder which predisposes to deafness, ventricular tachyarrhythmia, syncope, and sudden cardiac death. RESULTS: We here analyze the evolution of the common Gly38Ser variant (rs1805127), using genomic DNAs, complementary DNAs, and HEK293-expressed variants of altogether 19 mammalian species. The between species comparison reveals that the human-specific Gly38Ser polymorphism evolved under strong positive Darwinian selection, probably in adaptation to specific challenges in the fine-tuning of IKs channels. The involved amino acid exchanges (Asp > Gly, Gly > Ser) are moderately radical and do not induce apparent changes in posttranslational modification. According to population genetic analyses (HapMap phase II) a heterozygote advantage accounts for the maintenance of the Gly38Ser polymorphism in humans. On the other hand, the expression of the 38Ser allele seems to be disadvantageous under certain conditions, as suggested by the sporadic deficiency of 38Ser-coding mRNAs in heterozygote Central Europeans and the depletion of homozygotes 38Ser in the Yoruban sample. CONCLUSION: We speculate that individual differences in genomic imprinting or genomic recoding might have contributed to conflicting results of recent association studies between Gly38Ser polymorphism and QT phenotype. The findings thus highlight the relevance of mRNA data in future association studies of genotypes and clinical disorders. To the best of our knowledge, they moreover provide first time evidence for a unique pattern; i.e. coincidence of positive Darwinian selection and polymorphism with a sporadically suppressed expression of one allele.

Common variants at ten loci modulate the QT interval duration in the QTSCD Study.

The QT interval, a measure of cardiac repolarization, predisposes to ventricular arrhythmias and sudden cardiac death (SCD) when prolonged or shortened. A common variant in NOS1AP is known to influence repolarization. We analyze genome-wide data from five population-based cohorts (ARIC, KORA, SardiNIA, GenNOVA and HNR) with a total of 15,842 individuals of European ancestry, to confirm the NOS1AP association and identify nine additional loci at P < 5 x 10(-8). Four loci map near the monogenic long-QT syndrome genes KCNQ1, KCNH2, SCN5A and KCNJ2. Two other loci include ATP1B1 and PLN, genes with established electrophysiological function, whereas three map to RNF207, near LITAF and within NDRG4-GINS3-SETD6-CNOT1, respectively, all of which have not previously been implicated in cardiac electrophysiology. These results, together with an accompanying paper from the QTGEN consortium, identify new candidate genes for ventricular arrhythmias and SCD.

Do common genetic variants in endotoxin signaling pathway contribute to predisposition to alcoholic liver cirrhosis?

BACKGROUND: Tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta), produced by endotoxin-activated Kupffer cells, play a key role in the pathogenesis of alcoholic liver cirrhosis (ALC). Alleles TNFA -238A, IL1B -31T and variant IL1RN*2 of repeat polymorphism in the gene encoding the IL-1 receptor antagonist increase production of TNF-alpha and IL-1beta, respectively. Alleles CD14 -159T, TLR4 c.896G and TLR4 c.1196T modify activation of Kupffer cells by endotoxin. We confirmed the published associations between these common variants and genetic predisposition to ALC by means of a large case-control association study conducted on two Central European populations. METHODS: The study population comprised a Czech sample of 198 ALC patients and 370 controls (MONICA project), and a German sample of 173 ALC patients and 331 controls (KORA-Augsburg), and 109 heavy drinkers without liver disease. RESULTS: Single locus analysis revealed no significant difference between patients and controls in all tested loci. Diplotype [IL1RN 2/ 2; IL1B -31T+] was associated with increased risk of ALC in the pilot study, but not in the validation samples. CONCLUSIONS: Although cytokine mediated immune reactions play a role in the pathogenesis of ALC, hereditary susceptibility caused by variants in the corresponding genes is low in Central European populations.

The non-synonymous coding IKr-channel variant KCNH2-K897T is associated with atrial fibrillation: results from a systematic candidate gene-based analysis of KCNH2 (HERG).

AIMS: Atrial fibrillation (AF) is the most frequent arrhythmia in humans. Rare familial forms exist. Recent evidence indicates a genetic susceptibility to common forms of AF. The alpha-subunit of the myocardial I(Kr)-channel, encoded by the KCNH2 gene, is crucial to ventricular and atrial repolarization. Patients with mutations in KCNH2 present with higher incidence of AF. Common variants in KCNH2 have been shown to modify ventricular repolarization. We intended to investigate, whether such variants may also modulate atrial repolarization and predispose to AF. METHODS AND RESULTS: In a two-stage association study we analysed 1207 AF-cases and 2475 controls. In stage I 40 tagSNPs (single nucleotide polymorphisms) from the KCNH2 genomic region were genotyped in 671 AF-cases and 694 controls. Of five associated variants, the common K897-allele of the KCNH2-K897T variant was replicated in n = 536 independent AF cases and n = 1781 controls in stage II [overall odds ratio 1.25, 95% confidence interval 1.11-1.41, P = 0.00033]. This association remained significant after adjustment for gender and age. CONCLUSION: We report a genetic association finding including positive replication between the K897-allele and higher incidence of AF. This provides a molecular correlate for complex genetic predispositions to AF. The consequences of the K897T variant at the atrial level will require further functional investigations.

Association of variants in the BAT1-NFKBIL1-LTA genomic region with protection against myocardial infarction in Europeans.

Single-nucleotide polymorphisms within the BAT1-NFKBIL1-LTA genomic region (6p21.3) and the LGALS2 gene (22q13.1), encoding a regulator for lymphotoxin-alpha, the product of the LTA gene, have been reported to be linked with the risk of myocardial infarction in Japanese. We employed nine polymorphisms from the BAT1-NFKBIL1-LTA region and one polymorphism from the LGALS2 gene, and investigated whether such associations were also present in Europeans. The study included 3657 patients with myocardial infarction and 1211 control individuals with angiographically normal coronary arteries. Minor homozygous genotypes of polymorphisms in BAT1 (rs2239527, -23C/G), NFKBIL1 (rs2071592, -63T/A) and LTA (rs1800683, -162G/A; rs909253, 252G/A; rs1041981, Thr26Asn) were associated with moderately protective effects against myocardial infarction (P

No replication of association between estrogen receptor alpha gene polymorphisms and susceptibility to myocardial infarction in a large sample of patients of European descent.

BACKGROUND: The effects of estrogen on blood vessels are partly due to changes in vascular cell gene expression and protein synthesis that are mediated by estrogen receptors. In previous association studies, the -397T/C (rs2234693) and -351A/G (rs9340799) single nucleotide polymorphisms in the estrogen receptor alpha gene (ESR1) have been implicated in the risk of coronary atherosclerosis and myocardial infarction. To test these findings, we examined the relationship of the polymorphisms to myocardial infarction in a large sample of white patients and control individuals of predominantly European descent. METHODS AND RESULTS: The case group included 3657 patients with myocardial infarction, and the control group comprised 1211 individuals with angiographically normal coronary arteries and without signs or symptoms of myocardial infarction. TaqMan assays were used for the determination of genotypes. Genotype distributions of the -397T/C and -351A/G polymorphisms were not significantly different between the control and patient groups (P> or =0.85). The frequencies of haplotypes defined by the -397T/C and -351A/G polymorphisms were similar in the control group and the patient group (P=0.42). In addition, the distributions of haplotype-defined genotypes (diplotypes) were not significantly different between the control group and the patient group (P=0.81). Separate analyses in women and men did not reveal sex-related associations of specific genotypes or haplotypes of the polymorphisms with myocardial infarction (P> or =0.25). CONCLUSIONS: The results indicate that the -397T/C and -351A/G polymorphisms of ESR1 or haplotypes based on these polymorphisms are not associated with myocardial infarction in a white population.

The intron 6 G/T polymorphism of c-myb oncogene and the risk for coronary in-stent restenosis.

BACKGROUND: The principle mechanisms leading to the development of atherosclerosis are long-term accumulation of lipids and cell proliferation. We have recently shown that a single nucleotide polymorphism in the c-myb gene is associated with the development of coronary artery disease in humans and intracellular lipid accumulation. C-myb expression has been further shown to be up-regulated during cell proliferation. The development of in-stent restenosis is predominantly driven by smooth muscle cell proliferation. METHODS: To study a possible association of c-myb with neointima formation in humans we genotyped 485 consecutive patients undergoing coronary stenting for a G/T-single nucleotide polymorphism in intron 6 of the cmyb gene. Restenosis was assessed by quantitative coronary angiography and angiographic follow-up after 6 months. To study the effect of c-myb on smooth muscle cell proliferation primary human smooth muscle cells were infected with recombinant adenovirus expressing c-myb, a dominant negative myb-engrailed fusion protein or control virus. RESULTS AND CONCLUSION: Restenosis > 50% occurred in 27.6% of patients with at least one G-allele and in 20.8% of those without (p = 0.10). Even after adjustment for the independent risk factors diabetes mellitus, reference lumen diameter, smoking, dyslipidemia and number of diseased vessels, the observed difference in the distribution of the c-myb alleles did not reach statistical significance (p = 0.08). Adenoviral gene transfer of c-myb did not increase proliferation of cultured smooth muscle compared to control virus or untransfected cells, while the expression of the dominant negative mutant reduced proliferation of VSMC as previously shown. Our results indicate that expression of c-myb, while being important for cell cycle is not sufficient to induce smooth muscle cell proliferation. The G/T-nucleotide transversion polymorphism in intron 6 of the c-myb oncogene that has been associated with atherosclerosis and lipid accumulation is not a risk factor for human in-stent restenosis.