Pre-soil fumigation with ammonium bicarbonate and lime modulates the rhizosphere microbiome to mitigate clubroot disease in Chinese cabbage.

Background: Plasmodiophora brassicae is an ever-increasing threat to cruciferous crop production worldwide. Aims and methods: This study investigated the impact of pre-soil fumigation with ammonium bicarbonate (N) and lime (NB) to manage clubroot disease in Chinese cabbage through 16S rRNA gene amplification sequencing. Results: We found that soil fumigation with N and NB suppressed disease incidence by reducing the soil acidity and population of P. brassicae in the rhizosphere. Minimum disease incidence and maximum relative control effect of about 74.68 and 66.28% were achieved in greenhouse and field experiments, respectively, under the combined application of ammonium bicarbonate and lime (LNB) as compared with N, NB, and control (GZ). Microbial diversity analysis through Miseq sequencing proved that pre-soil fumigation with N, NB, and LNB clearly manipulated rhizosphere microbial community composition and changed the diversity and structure of rhizosphere microbes compared with GZ. Bacterial phyla such as Proteobacteria, Bacteriodetes, and Acidobacteria and fungal phyla including Olpidiomycota and Ascomycota were most dominant in the rhizosphere of Chinese cabbage plants. Soil fumigation with N and NB significantly reduced the abundance of clubroot pathogen at genus (Plasmodiophora) level compared with GZ, while decreased further under combined application LNB. Microbial co-occurrence network analysis showed a highly connected and complex network and less competition for resources among microbes under combined application LNB. Conclusion: We conclude that for environmentally friendly and sustainable agriculture, soil fumigation with combined ammonium bicarbonate and lime plays a crucial role in mitigating Chinese cabbage clubroot disease by alleviating soil pH, reducing pathogen population, and manipulating the rhizosphere microbiome.

Exploring the effect of different application rates of biochar on the accumulation of nutrients and growth of flue-cured tobacco (Nicotiana tabacum).

Background: Biochar application has become one of the most potential tools to improve soil fertility and plant growth for sustainable and eco-friendly agriculture. However, both positive and negative effects of biochar application have been recorded on plant growth and soil fertility. Methods: This study investigated the impact of different application rates (0, 600, 900, 1200, and 1800 kg/ha) of biochar on the soil nutrient contents, accumulation of nutrients and dry matter in different plant parts, and growth of flue-cured tobacco plants under field conditions. Results: Results demonstrated that soil organic carbon pool and carbon/nitrogen ratio were increased proportionally with the increasing dosage of biochar, 25.54 g/kg and 14.07 g/kg compared with control 17 g/kg and 10.13 g/kg, respectively. The contents of soil total nitrogen were also significantly increased after biochar application in the middle (1.77 g/kg) and late-growth (1.54 g/kg) stages of flue-cured tobacco than in control (1.60 g/kg and 1.41 g/kg, respectively). The contents of soil nitrate nitrogen were also higher under low (600 and 900 kg/ha) application rates of biochar and reduced when higher (1200 and 1800 kg/ha) dosages of biochar were applied. However, it was observed that varying application rates of biochar had no impact on soil ammonium nitrogen content during the growth period of flue-cured tobacco plants. The nutrient accumulation (N, P, K) in different parts of flue-cured tobacco plants was significantly increased under a low application rate of biochar, which enhanced the soil and plant analyzer development values, effective leaves number, growth, dry matter accumulation, and leaf yield of flue-cured tobacco. In contrast, the high biochar application rate (1200 and 1800 kg/ha) negatively impacted nutrient accumulation and growth of flue-cured tobacco. Conclusion: Conclusively, the optimum application of biochar (600 and 900 kg/ha) is beneficial for plant growth, soil fertility, accumulation of nutrients, and dry matter in different plant parts. However, excessive biochar application (> 900 kg/ha) could inhibit flue-cured tobacco plant growth. This study provides a theoretical foundation for biochar application in tobacco and other crop production to obtain agricultural sustainability and economic stability.

Ralstonia solanacearum differentially modulates soil physicochemical properties and rhizospheric bacteriome of resistant and susceptible tobacco cultivars.

Ralstonia solanacearum is a devastating soilborne pathogen which poses significant yield and economic losses to tobacco production globally. The impact of R. solanacearum on rhizosphere bacteriome and soil physicochemical characteristics in resistant and susceptible tobacco cultivars is poorly understood. This study aims to determine the effect of R. solanacearum on soil physicochemical parameters and rhizosphere bacteriome of resistant (K326) and susceptible (Hongda) tobacco cultivars at various growth stages. Results demonstrated that the contents of available potassium and phosphorus, as well as soil pH were significantly increased in K326 soils (CK and T2) compared with Hongda (T1) after 21, 42, and 63 days post-inoculation (dpi) of R. solanacearum except for available nitrogen which showed an opposite trend. The qPCR results showed a significant decrease in R. solanacearum population in rhizosphere of K326 (T2) compared to the Hongda (T1) at 21 and 63 dpi than that after 42 dpi. The rhizosphere bacteriome analysis through 16S rRNA amplicon sequencing revealed that rhizosphere bacterial community composition was significantly different between two tobacco cultivars (Hongda and K326) and this effect was more prominent after 63 dpi (93 days after post-transplantation), suggesting that each cultivar recruits a unique set of bacterial communities. There was no obvious difference observed in the rhizosphere bacteriome of CK (K326) and T2 (K326), which might be attributed to the same genetic makeup and inherent resistance of K326 to bacterial wilt infection. Analysis of co-occurrence networks revealed that the microbial network in T1 (Hongda) was more complex than those in T2 (K326) and CK (K326), while the networks in CK and T2 were almost identical. The present research highlights the time-course relationship between environmental factors and rhizosphere bacteriome of tobacco cultivars showing different levels of resistance against R. solanacearum. Conclusively, studying the plant-soil-microbe interaction system in susceptible and resistant tobacco cultivars may enable us to develop effective integrated disease control plans for the healthy production of tobacco crops.

CXC ligand 13 orchestrates an immunoactive microenvironment and enhances immunotherapy response in head and neck squamous cell carcinoma.

Objectives: This study aims to systematically explore the role of chemokine CXC ligand 13 (CXCL13) in head and neck squamous cell carcinoma (HNSCC). Methods: The Genotype-Tissue Expression (GTEx) and The Cancer Genome Atlas (TCGA) databases provided the RNA-seq data for cancer and normal tissues, respectively. Gene set enrichment analysis was applied to search the cancer hallmarks associated with CXCL13 expression. TIMER2.0 was the main platform used to investigate the immune cell infiltration related to CXCL13. Immunohistochemistry was applied to explore the relationship between CXCL13 and patients' prognosis and the relationship between CXCL13 and tertiary lymphoid structures (TLSs). Results: The expression of CXCL13 was upregulated in most tumors, including HNSCC. The higher expression of CXCL13 was closely related to the positive prognosis of HNSCC. CXCL13 was mainly expressed in B cells and CD8 + T cells, revealing the relationship between its expression and immune activation in the tumor microenvironment. Furthermore, immunohistochemistry and multiple fluorescence staining analysis of HNSCC samples showed a powerful correlation between CXCL13 expression, TLSs formation, and positive prognosis. Finally, CXCL13 significantly increased the response to cancer immunotherapy. Conclusions: CXCL13 may function as a potential biomarker for predicting prognosis and immunotherapy response and associate with TLSs in HNSCC.

Identification and functional analysis of serine protease inhibitor gene family of Eocanthecona furcellata (Wolff).

The predatory natural enemy Eocanthecona furcellata plays a crucial role in agricultural ecosystems due to its effective pest control measures and defensive venom. Predator venom contains serine protease inhibitors (SPIs), which are the primary regulators of serine protease activity and play key roles in digestion, development, innate immunity, and other physiological regulatory processes. However, the regulation mechanism of SPIs in the salivary glands of predatory natural enemies is still unknown. In this study, we sequenced the transcriptome of E. furcellata salivary gland and identified 38 SPIs genes named EfSPI1∼EfSPI38. Through gene structure, multiple sequence alignment and phylogenetic tree analysis, real-time quantitative PCR (RT-PCR) expression profiles of different developmental stages and different tissues were analyzed. RNAi technology was used to explore the gene function of EFSPI20. The results showed that these 38 EfSPIs genes contained 8 SPI domains, which were serpin, TIL, Kunitz, Kazal, Antistasin, Pacifastin, WAP and A2M. The expression profile results showed that the expression of different types of EfSPIs genes was different at different developmental stages and different tissues. Most of the EfSPIs genes were highly expressed in the egg stage. The EfSPI20, EfSPI21, EfSPI22, and EfSPI24 genes of the Pacifastin subfamily and the EfSPI35 gene of the A2M subfamily were highly expressed in the nymphal and adult stages, which was consistent with the RT-qPCR verification results. These five genes are positively correlated with each other and have a synergistic effect on E. furcellata, and they were highly expressed in salivary glands. After interfering with the expression of the EfSPI20 gene, the survival rate and predatory amount of male and female adults were significantly decreased. Taken together, we speculated some EfSPIs may inhibit trypsin, chymotrypsin, and elastase, and some EfSPIs may be involved in autoimmune responses. EfSPI20 was essential for the predation and digestion of E. furcellata, and the functions of other EfSPIs were discussed. Our findings provide valuable insights into the diversity of EfSPIs in E. furcellata and the potential functions of regulating their predation, digestion and innate immunity, which may be of great significance for developing new pest control strategies.

EVI2B Is a Prognostic Biomarker and Is Correlated with Monocyte and Macrophage Infiltration in Osteosarcoma Based on an Integrative Analysis.

Osteosarcoma (OS) is the most common malignant bone tumor. However, treatment strategies have not changed over the past 30 years. The relationship between OS and the immune microenvironment may provide a basis for the establishment of novel therapeutic targets. In this study, a large-scale gene expression dataset (GSE42352) was used to identify key genes in OS. A Target-OS dataset from the Cancer Genome Atlas was used as a validation set. Ecotropic viral integration site 2B (EVI2B) was significantly upregulated in OS tumor samples. Differentially expressed genes (DEGs) were identified between samples with high and low EVI2B expression in both the test and validation cohorts. The top three functions of DEGs determined by a gene set enrichment analysis (GSEA) were chemokine signaling, cytokine-cytokine receptor interaction, and Human T-cell leukemia virus 1 infection. A prognostic prediction model including EVI2B, DOCK2, and CD33 was constructed by a Cox regression analysis. This model indicated that EVI2B is an independent protective prognostic marker in OS. An analysis of immune infiltration further showed that high EVI2B expression levels were correlated with high levels of macrophage infiltration. Protein expression data derived from the Human Protein Atlas suggested EVI2B to be highly expressed in monocytes. Finally, we validated the elevated expression of EVI2B in OS cell lines and OS tissue samples; these results were consistent with those of the analyses of the GSE42352 and Target-OS datasets. Our integrative bioinformatics analysis and experimental results provide clear evidence for the prognostic value of EVI2B in OS and its close relationship with monocyte and macrophage infiltration.

Head-and-neck dermatofibrosarcoma protuberans: Survival analysis and Clinically relevant immunohistochemical indicators.

BACKGROUND: Head and neck dermatofibrosarcoma protuberans (HNDFSP) is extremely rare and not entirely understood. OBJECTIVE: To investigate the clinicopathological features of HNDFSP and identify the expression of its clinically relevant indicators, with the expectation of improving the existing treatment strategies. METHODS: A long-term follow-up of patients with HNDFSP who received treatment between 2000 and 2021 at Shanghai Ninth People's Hospital was conducted. The clinical, histological, and immunohistochemical data of the patients were retrieved and analyzed. The endpoint of the study was the incidence of significant disease-related clinical events (recurrences or metastasis). RESULTS: A total of 49 patients with HNDFSP were included in the study, with males (92.7%) predominating than females (7.3%). Eighteen patients developed recurrent disease (36.8%) after surgery, and the median time of recurrence was 48 months (interquartile, 20-74 months). Metastasis occurred in two cases (4.1%). Two patients died during follow-up, both with local recurrence, and one of them with intestinal metastasis. Post-operation radiotherapy was administered to eight patients (16.3%) and the effect in local control was remarkable. Age, tumor size, and negative margins with sufficient safety width were the main independent factors affecting the disease-free survival. Several potential targeted therapeutic indicators, including EZH2 (80.0%), EGFR (91.4%), PDGF (97.1%), PD-L1 (77.1%), and VEGF (77.1%), were positively expressed in most tumor samples. CONCLUSION: HNDFSP is rare, significantly challenging to control locally, and has a worse prognosis with current treatment strategies. Wide local excision and long-term follow-up are needed. Radiotherapy could improve the prognosis of patients with HNDFSP.

N-cadherin protects oral cancer cells from NK cell killing in the circulation by inducing NK cell functional exhaustion via the KLRG1 receptor.

BACKGROUND: Circulating tumor cells (CTCs) can survive in the circulation and return to primary tumors through a self-seeding process. However, the mechanisms underlying CTCs escape from natural killer (NK) cell-mediated immune surveillance remain unclear. METHOD: Self-seeded tumor cells were isolated and characterized using a modified contralateral seeding model. A comparison of transcriptional profiles was performed between the parental cells and self-seeded cells. The molecular mechanism of self-seeded tumor cells escaping from NK cell was demonstrated through in vitro experiments and verified in a CTC-mimicking in vivo model. Then, the expression level of key protein mediating CTCs immune escape was detected in 24 paired primary and recurrent tumor samples of patients with oral cancer by the immunohistochemical method. RESULT: Self-seeded cells displayed resistance to NK cell-mediated lysis and a higher tumor seeding ability than their parental cells. Elevated expression levels of the CDH2 gene and its protein product, N-cadherin were found in self-seeded cells. NK cells secreted cytokines, and fluid shear stress facilitated N-cadherin release by promoting A disintegrin and metalloprotease 10 (ADAM10) translation or converting the precursor ADAM10 to the mature form. Soluble N-cadherin triggered NK cell functional exhaustion by interacting with the killer cell lectin-like receptor subfamily G member 1 (KLRG1) receptor and therefore protected tumor cells from NK cell killing in the circulation. In vivo experimental results showed that overexpression of N-cadherin promoted tumor self-seeding and facilitated the survival of CTCs. Compared with primary tumors, N-cadherin expression was significantly increased in matched recurrent tumor tissues. CONCLUSION: Together, our findings illustrate an unknown mechanism by which CTCs evaded NK cell-mediated immune surveillance, and indicate that targeting N-cadherin is an effective strategy to prevent CTCs from homing to primary tumor.

Plant-Microbe Interaction: Mining the Impact of Native Bacillus amyloliquefaciens WS-10 on Tobacco Bacterial Wilt Disease and Rhizosphere Microbial Communities.

Ralstonia solanacearum, the causative agent of bacterial wilt disease, has been a major threat to tobacco production globally. Several control methods have failed. Thus, it is imperative to find effective management for this disease. The biocontrol agent Bacillus amyloliquefaciens WS-10 displayed a significant control effect due to biofilm formation, and secretion of hydrolytic enzymes and exopolysaccharides. In addition, strain WS-10 can produce antimicrobial compounds, which was confirmed by the presence of genes encoding antimicrobial lipopeptides (fengycin, iturin, surfactin, and bacillomycinD) and polyketides (difficidin, bacilysin, bacillibactin, and bacillaene). Strain WS-10 successfully colonized tobacco plant roots and rhizosphere soil and suppressed the incidence of bacterial wilt disease up to 72.02% by reducing the R. solanacearum population dynamic in rhizosphere soil. Plant-microbe interaction was considered a key driver of disease outcome. To further explore the impact of strain WS-10 on rhizosphere microbial communities, V3-V4 and ITS1 variable regions of 16S and ITS rRNA were amplified, respectively. Results revealed that strain WS-10 influences the rhizosphere microbial communities and dramatically changed the diversity and composition of rhizosphere microbial communities. Interestingly, the relative abundance of genus Ralstonia significantly decreased when treated with strain WS-10. A complex microbial co-occurrence network was present in a diseased state, and the introduction of strain WS-10 significantly changed the structure of rhizosphere microbiota. This study suggests that strain WS-10 can be used as a novel biocontrol agent to attain sustainability in disease management due to its intense antibacterial activity, efficient colonization in the host plant, and ability to transform the microbial community structure toward a healthy state. IMPORTANCE The plant rhizosphere acts as the first line of defense against the invasion of pathogens. The perturbation in the rhizosphere microbiome is directly related to plant health and disease development. The introduction of beneficial microorganisms in the soil shifted the rhizosphere microbiome, induced resistance in plants, and suppressed the incidence of soilborne disease. Bacillus sp. is widely used as a biocontrol agent against soilborne diseases due to its ability to produce broad-spectrum antimicrobial compounds and colonization with the host plant. In our study, we found that the application of native Bacillus amyloliquefaciens WS-10 significantly suppressed the incidence of tobacco bacterial wilt disease by shifting the rhizosphere microbiome and reducing the interaction between rhizosphere microorganisms and bacterial wilt pathogen.

Microbial Consortia: An Engineering Tool to Suppress Clubroot of Chinese Cabbage by Changing the Rhizosphere Bacterial Community Composition.

Clubroot disease, caused by Plasmodiophora brassicae, is a serious threat to Chinese cabbage (Brassica rapa subsp. pekinensis) production, which results in extensive yield losses. At present, clubroot control mainly depends upon pesticides, which provoke food-safety concerns, and the application of sole biocontrol agents cannot successfully control the disease. In this study, we investigated the effect of Bacillus cereus BT-23, Lysobacter antibioticus 13-6, and Lysobacter capsici ZST1-2 as sole strains, intra-/inter-genus co-culture, and microbial consortia on clubroot disease, plant growth, and rhizosphere bacterial diversity in a field experiment. The microbial consortia efficiently controlled the incidence of clubroot disease, with a biocontrol effect of about 65.78%, by decreasing the soil acidity and enhancing the yield (17,662.49 kg/acre). The high-throughput sequencing results demonstrated that the phyla Proteobacteria and Bacteroidetes were present in high relative abundance in the rhizosphere soil of the Chinese cabbage. Furthermore, Firmicutes was found as a unique phylum in the rhizosphere soil of CK-H and T1-T7, except for CK-D. The application of microbial consortia recovers the imbalance in indigenous microbial communities. Therefore, we conclude that microbial consortia can reduce the clubroot incidence in Chinese cabbage by decreasing the soil acidity and altering the diversity and structure of rhizosphere bacterial communities. This study highlights the potential of microbial consortia as an engineering tool to control devastating soilborne diseases in commercial crops.

Microbial Cross-Talk: Dissecting the Core Microbiota Associated With Flue-Cured Tobacco (Nicotiana tabacum) Plants Under Healthy and Diseased State.

Bacterial wilt caused by Ralstonia solanacearum is a devastating disease of flue-cured tobacco production which poses significant yield losses all around the world. In this study, we evaluated the rhizosphere microbiome of healthy and bacterial wilt-infected (diseased) flue-cured tobacco plants through amplification of V3-V4 and ITS1-5f variable regions of 16S and internal transcribed spacer (ITS) rRNA. The study was based on the location (Qujing, Shilin, and Wenshan), plant components (rhizosphere soil and roots), and sample types (healthy and diseased) to assess the diversity of bacterial and fungal communities. Bacterial and fungal communities present in roots primarily emanated from rhizosphere soil. Healthy flue-cured tobacco plants exhibit high microbial diversity compared to diseased plants. Among three variables, plant components significantly influence the diversity of microbial communities, whereas rhizosphere soil harbors higher microbial diversity than roots. Bacterial phyla Cyanobacteria and Proteobacteria were found in high relative abundance in roots and rhizosphere soil samples, respectively. As far as fungi is concerned, a high relative abundance of Ascomycota and Basidiomycota was found in both rhizosphere soil and root. Bacterial genera such as Bacillus, Bradyrhizobium, Ensifer, Neorhizobium, and Lysobacter related to plant growth promotion and disease suppressing abilities were dominant than fungal genera. Analysis of relative abundance at specie-level revealed that most fungal species are pathogenic to flue-cured tobacco and could provide a conducive environment for wilt infection. In conclusion, R. solanacearum significantly influences the microbial diversity of flue-cured tobacco plants and negatively affects the bacterial community composition. Altogether, our study demonstrates the complexity of bacterial and fungal communities that possibly interact with each other (microbe-microbe) and host (host-microbe). This cross-talk could be helpful for healthy flue-cured tobacco plant growth and to induce resistance against bacterial wilt disease.

Insights into the relevance between bacterial endophytic communities and resistance of rice cultivars infected by Xanthomonas oryzae pv. oryzicola.

Bacterial leaf streak (BLS) caused by Xanthomonas oryzae pv. oryzicola (Xoc), impacts the production of rice. However, several rice cultivars displayed resistance to Xoc in the field, but scarce information is available about the role of endophytic microbiota in disease resistance. In the present study, the endophytic bacterial communities of resistant and susceptible rice cultivars "CG2" and "IR24", respectively, were analyzed using high throughput 16S rRNA gene amplified sequencing and culture dependent method was further used for bacterial isolation. A total of 452,716 high-quality sequences representing 132 distinct OTUs (Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes) and 46 isolates of 16 genera were explored from rice leaves infected with Xoc. Community diversity of endophytic bacteria were higher in the leaves of the resistant cultivars compared to susceptible cultivars upon Xoc infection. Strikingly, this diversity might contribute to natural defense of the resistant cultivar against pathogen. Pantoea, which is pathogen antagonist, was frequently detected in two cultivars and higher abundance were recorded in resistant cultivars. Different abundance genus includes endophytic isolates with marked antagonistic activity to Xoc. The increased proportions of antagonistic bacteria, may contribute to resistance of rice cultivar against Xoc and the Pantoea genus was recruited by Xoc infection play a key role in suppressing the development of BLS disease in rice. Taken together, this work reveals the association between endophytic bacteria and BLS resistance in rice and identification of antagonism-Xoc bacterial communities in rice. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13205-021-02979-2.

Nerve growth factor (NGF)-TrkA axis in head and neck squamous cell carcinoma triggers EMT and confers resistance to the EGFR inhibitor erlotinib.

Understanding the molecular mechanisms regulating tumor dissemination and therapeutic resistance is of central importance for effective cancer therapies. Here, we report that nerve growth factor (NGF) and its receptor TrkA facilitate epithelial-mesenchymal transition (EMT) and EGFR inhibitor resistance via STAT3 activation in head and neck squamous cell carcinoma (HNSCC). Both NGF and TrkA expression were elevated in HNSCC, indicating poor clinical outcomes. NGF was highly expressed in cancer cells and nerves in perineural niche, whereas TrkA expression was higher in cancer cells with perineural invasion. The NGF/TrkA axis could promote HNSCC cell dissemination and trigger EMT via STAT3 activation. Moreover, we discovered that the NGF/TrkA axis conferred resistance to the EGFR inhibitor erlotinib via EMT processes in HNSCC cells. Blocking TrkA signaling markedly reversed EMT and sensitized HNSCC cells to erlotinib in both in vitro and in vivo models. Overall, our results demonstrate novel evidence that the paracrine NGF/TrkA axis favors EMT and confers EGFR-targeted therapeutic resistance in HNSCC.

The left ventricular lead electrical delay predicts response to cardiac resynchronisation therapy.

Up to one-third of patients who undergo cardiac resynchronisation therapy (CRT) are not responders. To identify potential responders to CRT may be sometimes difficult and time-consuming. Forty-five patients who had undergone CRT implantation for standard indications were evaluated. Electrical left ventricular (LV) lead location was assessed by left ventricular activation time (LVAT), LV lead electrical delay (LVLED), and RV-LV interlead electrical delay (RVsense-LVsense). Anatomic LV pacing location was assessed as basal or mid-ventricular between 3:00 to 5:00 (traditionally optimal site), and all the other positions (traditionally non-optimal site). CRT response was defined as a decrease in LV end-systolic volume (LVESV) exceeding 15% at six months. LVLED was larger in the responder group than that in the non-responder group (67.3 ± 8.5% vs. 55.3 ± 8.1%, P< 0.001). In the multivariate analysis, LVLED and cLBBB morphology were the two independent predictors of positive echocardiographic response to CRT (OR=1.180, P=0.003; OR=7.497, P=0.04, respectively). A cutoff value of LVLED> 54.82% predicted responders with 96.3% sensitivity and 75.2% specificity and the area under the receiver operating characteristic (ROC) curve was 0.844 for LVLED (P=0.002). No relationship was found between the anatomic LV pacing sites and response to CRT (P=0.188). The larger left ventricular lead electrical delay may predict response to cardiac resynchronisation therapy.

Left ventricular endocardial pacing predicts the reduction of left ventricular outflow tract pressure gradient immediately after percutaneous transseptal myocardial ablation in patients with hypertrophic obstructive cardiomyopathy refractory to medication.

BACKGROUND: Hypertrophic obstructive cardiomyopathy (HOCM) carries an increased risk for sudden cardiac death. No data regarding the percutaneous transseptal myocardial ablation (PTSMA) and epicardial left ventricular pacing (LVP) were reported. METHODS: Seven patients with recurrent symptoms and increased resting left ventricular outflow tract pressure gradient (LVOTG) after PTSMA and another 14 patients with HOCM without history of PTSMA were studied. Both resting and dobutamine stress echocardiography, PTSMA and LVP were routinely performed. RESULTS: In patients without previous PTSMA procedure, mild reduction of resting LVOTG was detected at 5 minutes after left ventricular pacing, and this reduction became significant at 10 minutes. All patients were divided into successful and unsuccessful groups according to their response to LVP. In contrary to patients in unsuccessful group, resting and R-S2 stimuli-induced LVOTG during PTSMA procedure were decreased dramatically ((9 +/- 5) mmHg vs (58 +/- 12) mmHg, (12 +/- 2) mmHg vs (113 +/- 27) mmHg, P < 0.001). Analysis of Logistic regression demonstrated that only LVOTG level during left ventricular pacing was an independent factor predicting the reduction of LVOTG immediately after PTSMA (odds ratio (OR), 0.59; 95% CI 2.67 to 5.82; P = 0.0002). CONCLUSION: Left ventricular endocardial temporary pacing plays a critical role in predicting acute effect on the reduction of LVOTG immediately after PTSMA procedure.