Variations in atrial fibrillation ablation utilization and reimbursement among medicare beneficiaries: an observational study from 2013 to 2019

Background

Atrial fibrillation (AF) pulmonary vein isolation ablation has been utilized increasingly yet variably in the USA.

Purpose

To identify variations in AF ablation utilization and reimbursement among Medicare beneficiaries (MB).

Methodology

We used a 100% sample of MB who underwent AF ablation from 2013 to 2019. We stratified data geographically (Northeast, South, West, and Midwest), identified the mean AF prevalence and the number of AF ablations per 100,000 MB, and examined the correlation between AF prevalence and ablation. We also examined the number of cardiologists performing AF ablation per 100,000 MB and the average number of AF ablation per individual cardiologist (ablation/cardiologist), as well as average submitted charge (ASC) for AF ablation. Additionally, we stratified data per urban versus rural areas as well as the gender of performing cardiologists and examined ablation/cardiologist and the ASC.

Results

Geographic analysis: The mean AF prevalence, the rates AF ablation per 100,000 MB, the number of cardiologists per 100,000 MB, and ablation/cardiologist have shown a steady increase in all regions across years. In all years, the mean AF prevalence was significantly different among regions with the highest prevalence in the Northeast and the lowest in the West (all P<0.001), however, there was no significant difference in the rates of AF ablation per 100,000 MB (all P≥0.056). There was significant correlation between AF prevalence and ablation only in the Midwest and the West, with 46.4% and 43.4% positive correlation respectively (P≤0.0001). The number of cardiologists performing AF ablation per 100,000 MB was not significantly different among regions in all years (All P≥0.48), however, ablation/cardiologist was significantly higher in the West and the South compared to the Northeast and the Midwest (All P<0.0001). On the contrary, the ASC has shown steady decrease in all regions. The ASC was significantly different among regions in all year (all P≤0.003) with higher ASC in the Midwest and the Northeast compared to the south and the West.

Urban vs rural analysis: Ablation/cardiologist was not significantly different between urban and rural areas in all years (all P≥0.068) except in 2013 when it was significantly higher in urban areas (P=0.004). The ASC was significantly higher in rural areas only in 2015 and 2019 (P=0.037 and P=0.029 respectively) however, there was no significant difference in the rest of the years (P≥0.07).

Gender analysis: Ablation/cardiologist was not significantly different between male and female cardiologists in all years (P≥0.056) except in 2017 when the average was significantly higher per male cardiologists (P=0.007). The ASC was not significantly different in all years (P≥0.362).

Conclusion

There are variations in AF ablation utilization and reimbursement among MB in the USA according to geographic, urban and rural regions, and the gender of performing cardiologists.

Funding Acknowledgement

Type of funding sources: None.

Schizophrenia in an adult with 6p25 deletion syndrome

Chromosomal deletions at 6p25-p24 are rare findings in patients with developmental delay. There is limited information about the adult phenotype. We present a 36-year-old patient with schizophrenia, mild mental retardation, progressive hearing deficits, and characteristic facial features. Ocular (Axenfeld-Rieger anomaly) abnormalities were diagnosed in infancy; vision, however, has remained unimpaired. There were no other major congenital anomalies. Brain imaging showed only minor changes. There was no family history of intellectual deficits or psychosis. Karyotyping revealed a 6p25 deletion, and detailed fluorescence in situ hybridization (FISH) analyses using 23 probes confirmed a 6.7 Mb 6p25-pter deletion. The breakpoint is near a possible 6p25-p24 locus for schizophrenia. Psychotic illness may be part of the neurodevelopmental abnormalities and long-term outcome of patients with 6p terminal deletions. Other similarly affected patients likely remain to be diagnosed in adult populations of schizophrenia and/or mental retardation.

Mapping of three translocation breakpoints associated with orofacial clefting within 6p24 and identification of new transcripts within the region

Orofacial clefting (OFC) is a common congenital malformation. Here we report the refinement of three translocation breakpoints of patients exhibiting OFC within the 6p24 region, and the isolation and characterisation of novel genes, one of which is directly disrupted by the translocation breakpoint of a patient. The gene has been characterized and orthologues identified in bovine, murine and pufferfish.

Molecularly defined interstitial tandem duplication 6p case with mild manifestations

An interstitial tandem duplication of 6p21.1-p22.2 was found in a girl at 11 months of age when she was evaluated for developmental delay. Previous cases reported with partial 6p duplication usually have involved terminal duplications, with breakpoints ranging from 6p11 to 6p25. Our patient exhibits a milder phenotype compared to the previously reported cases in the literature. Features that she has in common with the other cases include craniofacial anomalies, such as broad nasal bridge and bulbous tip, thin lips, incomplete development of the scapha helix bilaterally, mild spastic paraparesis of the lower extremities, gross motor delay, and mild cognitive delays.

A serpin gene cluster on human chromosome 6p25 contains PI6, PI9 and ELANH2 which have a common structure almost identical to the 18q21 ovalbumin serpin genes

The human genes encoding the "ovalbumin" subgroup of closely related serine proteinase inhibitors (serpins) are located at 18q21.3 and 6p25. Those at 6p25 include proteinase inhibitor 6 (PI-6; gene symbol PI6), proteinase inhibitor 9 (PI-9; gene symbol PI9) and monocyte neutrophil elastase inhibitor (M/NEI; gene symbol ELANH2). Here we describe the fine mapping of these genes to a 200-kb region of chromosome 6 that includes the markers WI-8835 and D6S1338, and the establishment of the gene order: tel-PI6-PI9-ELANH2-cen. PI6 and ELANH2 are transcribed towards the telomere, and structural analysis shows that PI6 and PI9 are organized identically, having seven exons and six introns. PI6 and PI9 are almost identical in structure to the ovalbumin serpin genes at 18q21.3. The 18q21.3 genes have an extra exon and intron, otherwise all the other exon/intron boundaries are conserved between the two groups. These results represent the first detailed map of the chromosome 6 serpin gene cluster, and demonstrate that although they are very closely related, the 6p25 and 18q21-->q23 ovalbumin serpin genes form two structurally distinct groups. These findings do not support a previously proposed model for evolution of the clusters which invoked an inter-chromosomal duplication of the entire 6p25 group to 18q21.3.

Molecular cloning, chromosomal mapping, and developmental expression of a novel protein tyrosine phosphatase-like gene

Protein tyrosine phosphatases (PTPs) mediate the dephosphorylation of phosphotyrosine. PTPs are known to be involved in many signal transduction pathways leading to cell growth, differentiation, and oncogenic transformation. We have cloned a new family of novel protein tyrosine phosphatase-like genes, the Ptpl (protein tyrosine phosphatase-like; proline instead of catalytic arginine) gene family. This gene family is composed of at least three members, and we describe here the developmental expression pattern and chromosomal location for one of these genes, Ptpla. In situ hybridization studies revealed that Ptpla expression was first detected at embryonic day 8.5 in muscle progenitors and later in differentiated muscle types: in the developing heart, throughout the liver and lungs, and in a number of neural crest derivatives including the dorsal root and trigeminal ganglia. Postnatally Ptpla was expressed in a number of adult tissues including cardiac and skeletal muscle, liver, testis, and kidney. The early expression pattern of this gene and its persistent expression in adult tissues suggest that it may have an important role in the development, differentiation, and maintenance of a number of different tissue types. The human homologue of Ptpla (PTPLA) was cloned and shown to map to 10p13-p14.

An interstitial deletion of 6p24-p25 proximal to the FKHL7 locus and including AP-2alpha that affects anterior eye chamber development

The FKHL7 gene has been implicated in the pathogenesis of glaucoma/autosomal dominant iridogoniodysgenesis (IGDA) (IRID1). This has been supported by mutations in some glaucoma and IGDA patients and the development of anterior eye chamber anomalies in patients with 6p deletions affecting the 6p25 region. We report a case with anterior eye chamber anomalies and an interstitial deletion of 6p24-p25 that does not include the FKHL7 gene, suggesting the possible additional involvement of another locus, within 6p24-6p25, in anterior eye chamber development. A candidate gene is AP-2alpha, which is contained within the deleted segment and plays a role in anterior eye chamber development.

Human epidermal differentiation complex in a single 2.5 Mbp long continuum of overlapping DNA cloned in bacteria integrating physical and transcript maps

Terminal differentiation of keratinocytes involves the sequential expression of several major proteins which can be identified in distinct cellular layers within the mammalian epidermis and are characteristic for the maturation state of the keratinocyte. Many of the corresponding genes are clustered in one specific human chromosomal region 1q21. It is rare in the genome to find in such close proximity the genes belonging to at least three structurally different families, yet sharing spatial and temporal expression specificity, as well as interdependent functional features. This DNA segment, termed the epidermal differentiation complex, contains 27 genes, 14 of which are specifically expressed during calcium-dependent terminal differentiation of keratinocytes (the majority being structural protein precursors of the cornified envelope) and the other 13 belong to the S100 family of calcium binding proteins with possible signal transduction roles in the differentiation of epidermis and other tissues. In order to provide a bacterial clone resource that will enable further studies of genomic structure, transcriptional regulation, function and evolution of the epidermal differentiation complex, as well as the identification of novel genes, we have constructed a single 2.45 Mbp long continuum of genomic DNA cloned as 45 p1 artificial chromosomes, three bacterial artificial chromosomes, and 34 cosmid clones. The map encompasses all of the 27 genes so far assigned to the epidermal differentiation complex, and integrates the physical localization of these genes at a high resolution on a complete NotI and SalI, and a partial EcoRI restriction map. This map will be the starting resource for the large-scale genomic sequencing of this region by The Sanger Center, Hinxton, U.K.

Delineation of two distinct 6p deletion syndromes

Deletions of the short arm of chromosome 6 are relatively rare, the main features being developmental delay, craniofacial malformations, hypotonia, and defects of the heart and kidney, with hydrocephalus and eye abnormalities occurring in some instances. We present the molecular cytogenetic investigation of six cases with 6p deletions and two cases with unbalanced translocations resulting in monosomy of the distal part of 6p. The breakpoints of the deletions have been determined accurately by using 55 well-mapped probes and fluorescence in situ hybridization (FISH). The cases can be grouped into two distinct categories: interstitial deletions within the 6p22-p24 segment and terminal deletions within the 6p24-pter segment. Characteristics correlating with specific regions are: short neck, clinodactyly or syndactyly, brain, heart and kidney defects with deletions within 6p23-p24; and corneal opacities/iris coloboma/Rieger anomaly, hypertelorism and deafness with deletions of 6p25. The two cases with unbalanced translocations presented with a Larsen-like syndrome including some characteristics of the 6p deletion syndrome, which can be explained by the deletion of 6p25. Such investigation of cytogenetic abnormalities of 6p using FISH techniques and a defined set of probes will allow a direct comparison of reported cases and enable more accurate diagnosis as well as prognosis in patients with 6p deletions.

Further evidence for the involvement of human chromosome 6p24 in the aetiology of orofacial clefting

Chromosomal translocations affecting the 6p24 region have been associated with orofacial clefting. Here we present a female patient with cleft palate, severe growth retardation, developmental delay, frontal bossing, hypertelorism, antimongoloid slant, bilateral ptosis, flat nasal bridge, hypoplastic nasal alae, protruding upper lip, microretrognathia, bilateral, low set, and posteriorly rotated ears, bilateral microtia, narrow ear canals, short neck, and a karyotype of 46,XX,t(6;9)(p24;p23). The translocation chromosomes were analysed in detail by FISH and the 6p24 breakpoint was mapped within 50-500 kb of other breakpoints associated with orofacial clefting, in agreement with the assignment of such a locus in 6p24. The chromosome 9 translocation breakpoint was identified to be between D9S156 and D9S157 in 9p23-p22, a region implicated in the 9p deletion syndrome.