Spontaneous thrombosis of a giant aneurysm complicated with the coronary-to-pulmonary artery fistula: a case report.

Background: A coronary-to-pulmonary artery fistula (CPAF) with a giant aneurysm is a rare clinical occurrence. The rupture of an aneurysm leads to a fatal outcome, thus prompting the incorporation of prophylactic measures, which have encompassed surgical resections or endovascular embolization procedures. The indications for these treatment strategies are controversial, and little has been elucidated regarding the salient characteristics underpinning the selection of a therapeutic strategy. We report a case of a giant aneurysm associated with CPAFs that was thrombosed before interventional treatment. Case summary: A 43-year-old woman, who had previously undergone a right adrenalectomy for primary aldosteronism, was referred for an abnormal heart silhouette on a chest X-ray, which had not been seen three years earlier. Contrast-enhanced computed tomography and coronary angiography (CAG) revealed a giant aneurysm on the anterior aspect of the heart associated with two CPAFs. Because of the risk of rupture of the aneurysm, surgical resection was recommended; however, the patient requested endovascular therapy. On the day of intervention, CAG showed spontaneous occlusion of the feeding vessel to the aneurysm, and the aneurysm showed minimal contrast agent, suggesting spontaneous thrombosis. Because of possible recanalization of the aneurysm, coil embolization was performed, without complications. The patient remained asymptomatic, and the aneurysm was completely embolized at the one-year follow-up. Discussion: The case shows that minimally invasive endovascular treatment is feasible instead of surgical resection for giant aneurysms associated with CPAFs, depending on their morphological characteristics. This perspective may offer novel insights into treatment strategies for CPAF.

Impact of Transcatheter Aortic Valve Replacement on Cardiac Reverse Remodeling and Prognosis in Mixed Aortic Valve Disease.

BACKGROUND: The management of mixed aortic valve disease (MAVD), defined as the concomitant presence of aortic stenosis (AS) and aortic regurgitation, remains a clinical challenging. The present study assessed the impact of transcatheter aortic valve replacement (TAVR) on cardiac geometry and prognosis in patients with MAVD. METHODS AND RESULTS: A retrospective multicenter TAVR registry was conducted, including patients who underwent TAVR for severe symptomatic AS between January 2015 and March 2019. Patients were subdivided into 2 groups according to concomitant presence of moderate or more severe aortic regurgitation as the MAVD group, and with mild or less severe aortic regurgitation as the isolated AS group. The primary outcome was a composite of cardiovascular death and rehospitalization due to cardiovascular causes. A total of 1742 patients (isolated AS, 1522 patients; MAVD, 220 patients) were included (84.0±5.2 years). Although MAVD exhibited significantly larger left ventricular volumes and higher left ventricular mass index at the TAVR procedure than isolated AS (respectively, P<0.001), MAVD showed a greater improvement of left ventricular volumes and left ventricular mass index after TAVR (respectively, P≤0.001). During a median follow-up of 747 days, 301 patients achieved the primary event. The prognosis post-TAVR was comparable between the 2 groups (log-rank P=0.65). Even after adjustment using propensity score matching to reduce the potential bias between the 2 groups, similar results were obtained for the entire cohort. CONCLUSIONS: Despite more advanced cardiac remodeling in MAVD at the time of TAVR compared with isolated AS, a greater improvement of cardiac reverse remodeling was found in MAVD, and the prognosis following TAVR was comparable between the 2 groups.

Unsupervised cluster analysis reveals different phenotypes in patients after transcatheter aortic valve replacement.

Aims: The aim of this study was to identify phenotypes with potential prognostic significance in aortic stenosis (AS) patients after transcatheter aortic valve replacement (TAVR) through a clustering approach. Methods and results: This multi-centre retrospective study included 1365 patients with severe AS who underwent TAVR between January 2015 and March 2019. Among demographics, laboratory, and echocardiography parameters, 20 variables were selected through dimension reduction and used for unsupervised clustering. Phenotypes and outcomes were compared between clusters. Patients were randomly divided into a derivation cohort (n = 1092: 80%) and a validation cohort (n = 273: 20%). Three clusters with markedly different features were identified. Cluster 1 was associated predominantly with elderly age, a high aortic valve gradient, and left ventricular (LV) hypertrophy; Cluster 2 consisted of preserved LV ejection fraction, larger aortic valve area, and high blood pressure; and Cluster 3 demonstrated tachycardia and low flow/low gradient AS. Adverse outcomes differed significantly among clusters during a median of 2.2 years of follow-up (P < 0.001). After adjustment for clinical and echocardiographic data in a Cox proportional hazards model, Cluster 3 (hazard ratio, 4.18; 95% confidence interval, 1.76-9.94; P = 0.001) was associated with increased risk of adverse outcomes. In sequential Cox models, a model based on clinical data and echocardiographic variables (χ2 = 18.4) was improved by Cluster 3 (χ2 = 31.5; P = 0.001) in the validation cohort. Conclusion: Unsupervised cluster analysis of patients after TAVR revealed three different groups for assessment of prognosis. This provides a new perspective in the categorization of patients after TAVR that considers comorbidities and extravalvular cardiac dysfunction.

Pulmonary pressure-flow responses to exercise in heart failure treated with angiotensin receptor neprilysin inhibitor.

BACKGROUND: The role of the angiotensin receptor neprilysin inhibitor (ARNI) in cardiac function, particularly its impact on pulmonary circulation, remains underexplored. Recent studies have described abnormal mean pulmonary artery pressure (mPAP)-cardiac output (CO) responses as having the potential to assess the disease state. The aim of this study was to assess the effects of ARNI on pulmonary circulation in heart failure. We measured echocardiographic parameters post 6-min walk (6 MW) and compared the changes with baseline and follow-up. Our hypothesis was that pulmonary pressure-flow relationship of the pulmonary circulation obtained by 6 MW stress echocardiography would be improved with treatment. METHODS: We prospectively enrolled 39 heart failure patients and conducted the 6 MW test indoors. Post-6 MW echocardiography measured echocardiographic variables, and CO was derived from electric cardiometry. Individualized ARNI doses were optimized, with follow-up echocardiographic evaluations after 1 year. RESULTS: Left ventricular (LV) volume were significantly reduced (160.7 ± 49.6 mL vs 136.0 ± 54.3 mL, P < 0.001), and LV ejection fraction was significantly improved (37.6 ± 11.3% vs 44.9 ± 11.5%, P < 0.001). Among the 31 patients who underwent 6 MW stress echocardiographic study at baseline and 1 year later, 6 MW distance increased after treatment (380 m vs 430 m, P = 0.003). The ΔmPAP/ΔCO by 6 MW stress decreased with treatment (6.9 mmHg/L/min vs 2.8 mmHg/L/min, P = 0.002). The left atrial volume index was associated with the response group receiving ARNI treatment for pulmonary circulation. CONCLUSIONS: Initiation of ARNI was associated with improvement of left ventricular size and LVEF. Additionally, the 6 MW distance increased and the ΔmPAP/ΔCO was improved to within normal range with treatment.

Correlation between energy loss index and B-type natriuretic peptide: a vector flow mapping study.

BACKGROUND: Vector Flow Mapping (VFM) and Energy Loss (EL) evaluation are emerging echocardiographic techniques that offer detailed insights into cardiac function. This study aimed to explore the relationship between EL parameters and B-type natriuretic peptide (BNP) levels, a well-established marker of heart failure severity. METHODS: Our study prospectively enrolled 62 patients experiencing shortness of breath and suspected heart failure, who underwent echocardiography and had BNP levels measured between January 2018 and August 2020. Patients were stratified based on BNP levels, and their clinical and echocardiographic characteristics were evaluated. Univariate and multivariate regression analyses were performed to assess the correlation between BNP levels and various echocardiographic variables, including VFM parameters. RESULTS: Patients were stratified into two groups based on their BNP levels: BNP < 200 pg/ml (n = 53) and BNP ≥ 200 pg/ml (n = 9). Patients with BNP ≥ 200 pg/ml presented significantly different clinical and echocardiographic characteristics, such as older age, larger left ventricular mass and volume indices, higher pulmonary artery systolic pressure, higher E/e' ratio, and larger EL parameters. Multivariate regression analysis demonstrated the E/e' ratio and ELA (EL during Atrial contraction phase/A wave ratio as significant determinants of logBNP. Receiver operating characteristic curve analysis showed ELA/A > 36.0 J/m2 as a significant predictor of high BNP with 89% sensitivity and 85% specificity. ELA/A demonstrated an incremental diagnostic value over elevated left atrial pressure for predicting high BNP (C statistic = 0.98 vs 0.74, P = 0.006). CONCLUSION: This study provides novel insights into the potential utility of EL parameters as auxiliary indicators of cardiac load, thereby enhancing our understanding of heart failure.

The Clinical Utility of Noninvasive Forrester Classification in Acute Heart Failure from PREDICT Study.

The Forrester classification plays a crucial role in comprehending the underlying pathophysiology of heart failure (HF) and is employed to categorize the severity and predict the outcomes of patients with acute HF. Our objective was to assess the predictive value of the Forrester classification, based on noninvasive hemodynamic measurements obtained through Doppler echocardiography at admission, in forecasting the short-term prognosis posthospitalization of patients with acute HF. Patients were recruited for the Prospect trial to elucidate the utility of EchocarDIography-based Cardiac ouTput in acute heart failure (PREDICT) study, a multicenter, prospective study conducted in Japan. Participants were stratified into 4 profiles using cardiac index (CI) and early mitral filling velocity (E)/early-diastolic mitral annular velocity (e') ratio obtained from Doppler echocardiography upon admission (profile I: CI >2.2, E/e' ≤15, profile II: CI >2.2, E/e' >15, profile III: CI ≤2.2, E/e' ≤15, profile IV: CI ≤2.2, E/e' >15). The primary composite outcome of the study was all-cause mortality or worsening HF during the 14 days of hospitalization. Cox proportional hazards model analysis was employed to identify prognostic factors during the observation period. A total of 270 subjects, with a mean age of 74 ± 14 years and a male proportion of 60%, were enrolled in the study. During the 14-day period of hospitalization, 58 participants (22%) had a composite outcome. Patients with low CI (i.e., profiles III and IV) demonstrated an elevated risk of composite outcome after adjusting for confounding variables, as evidenced by the adjusted hazard ratios of 5.85 (95% confidence interval 1.17 to 29.09, p <0.01, vs profile III) and 6.50 (95% confidence interval 1.53 to 27.68, p <0.01, vs profile IV) in comparison with profile I, respectively. In conclusion, the Forrester classification, derived from noninvasive Doppler echocardiography at admission, may predict early deterioration in patients hospitalized with acute HF.

Effectiveness of surveillance by echocardiography for cancer therapeutics-related cardiac dysfunction of patients with breast cancer.

BACKGROUND: Cancer therapeutics-related cardiac dysfunction (CTRCD) affect the prognosis of patients with breast cancer. Echocardiographic surveillance of patients treated with anti-human epidermal growth factor receptor type 2 (HER2) antibodies has been recommended, but few reports have provided evidence on patients with breast cancer only. We aimed to evaluate the effectiveness of echocardiographic surveillance for breast cancer patients. METHODS: We identified 250 patients with breast cancer who were treated with anti-HER2 antibodies from July 2007 to September 2021. We divided 48 patients with echocardiographic surveillance every 3 months into the surveillance group and 202 patients without echocardiographic surveillance into the non-surveillance group. In the surveillance group, patients with a considerable reduction in global longitudinal strain of 15 % were considered for the initiation of cardioprotective drugs. The composite outcome of CTRCD and acute heart failure was the study endpoint. RESULTS: The mean age was 59 ±â€¯12 years. During the follow-up period of 15 months (12-17 months), 12 patients reached the endpoint. The surveillance group had significantly lower incidence of the composite outcome (2.1 % vs. 5.5 %, adjusted odds ratio: 0.28, 95 % confidential intervals: 0.09-0.94; p = 0.039) and higher rates of prescriptions of cardioprotective drugs than the non-surveillance group. CONCLUSIONS: The incidence of cardiac complications was significantly lower in the surveillance group than the non-surveillance group, which supports the effectiveness of echocardiographic surveillance in patients with breast cancer.

Isoproterenol loading transesophageal echocardiography in atrial fibrillation.

In patients with sludge or severe spontaneous echo contrast (SEC) in the left atrial appendage (LAA), cases with isoproterenol loading transesophageal echocardiography (ISP-TEE) have been reported to identify the presence of thrombus in the LAA. This study aimed to assess the validity and hemodynamic changes of ISP-TEE in the LAA. We prospectively enrolled patients with atrial fibrillation (AF) who underwent ISP-TEE. The degree of sludge/SEC was categorized as being either absent (grade 0), mild SEC (grade 1), moderate SEC (grade 2), severe SEC or sludge (grade 3). The hemodynamic evaluation was performed by measuring LAA flow velocity, LAA tissue Doppler imaging (LAA-TDI) velocity, and pulmonary vein systolic forward flow velocity (PVS). In total, 35 patients (mean age 71 ± 7 years; 71% male) underwent ISP-TEE. Among 35 patients, 30 patients had grade 3 or 2 SEC, 5 patients had grade 1 SEC. After ISP loading, 23 patients (66% of all patients) showed improved sludge/SEC and one patient was diagnosed with thrombus in the LAA. There were 25 patients with grade 1 SEC, or no SEC (classified as Group1), 10 patients had residual sludge or grade 2 to 3 SEC (classified as Group2) after ISP administration. LAA flow, LAA-TDI, and PVS velocities were significantly higher in group 1 than in group 2 after ISP administration. There was no complication during the examination and after 24 h and 3 months. ISP infusion may be a potential tool to recognize LAA thrombus under the sludge/SEC during TEE in AF.

Association between cardiovascular risk factors and left ventricular strain distribution in patients without previous cardiovascular disease.

BACKGROUND: Some cardiovascular (CV) risk factors, such as hypertension and diabetes mellitus, have been reported to reduce left ventricular (LV) longitudinal strain (LS) even in patients with preserved LV ejection fraction. We hypothesized that multiple CV risk factors might cause changes in myocardial strain. Our study aimed to assess the association between multiple CV risk factors and strain in patients without previous CV disease (CVD). METHODS: We retrospectively evaluated 137 patients without CVD, who underwent echocardiography at our institution between May 2017 and February 2020. They were divided into four groups based on the number of risk factors (group 0: no risk factor, group 1: one risk factor, group 2: two risk factors, and groups 3: three or four risk factors). Risk factors were hypertension, dyslipidemia, diabetes mellitus, and chronic kidney disease. Absolute values of global LS (GLS) and relative apical LS ratio (RALSR) defined using the equation: average apical LS/(average basal LS + average mid LS) and was used as a marker of strain distribution. RESULTS: Out of 137 patients, group 0 had 35 patients, group 1 had 35 patients, group 2 had 32 patients, and group 3 had 35 patients. GLS was 22.4 ± 2.0%, 21.7 ± 2.1%, 21.3 ± 1.8%, 20.7 ± 2.2%, and RALSR was 0.64 ± 0.06, 0.66 ± 0.06, 0.68 ± 0.08, 0.69 ± 0.07 in groups 0-3, respectively. The one-way ANOVA detected significant differences between groups in GLS (p = 0.005) and RALSR (p = 0.037), respectively. Group 3 had a significantly lower GLS and higher RALSR than group 0 (p < 0.05). CONCLUSION: In patients without previous CVD, LS decreased especially from the basal segment as the number of cardiovascular risks increased. The segmental LS may be markers of occult LV dysfunction in patients with CV risk factors.

Nanotextured Mold Surface with DLC Coating for Reduction in Residual Ceramic Particles.

In the ceramic industry, ceramic particles remain on a mold surface due to which the mold requires frequent cleaning during press molding, reducing productivity. Surface texturing and tetrahedral amorphous carbon (ta-C) coatings are well-known surface-energy controllable treatments developed for low adhesion, low friction, and high wear resistance. In the present paper, we demonstrate the effect of reducing ceramic residues using nanotexturing, ta-C coatings, and their combination. We compare two surface morphologies (i.e., 770 nm pitch nanotexturing and flat) and five materials (i.e., nonhardened steel, hardened steel, ta-C, and two types of nitrogen-doped ta-C (ta-CNx). Molding test results show that the ta-C coating on flat surfaces with the highest hardness of 30 GPa shows the lowest residual amount of 5.9 µg for Al2O3 ceramic particles. The amount is 82% less than that of the nonhardened steel. The ta-CNx20, made with a nitrogen flow rate of 20 sccm, shows the lowest residual amount of 234 µg for SiO2 ceramic particles, which is 81% less than that of the nontextured ta-CNx20. In conclusion, we provide design guidelines for nanotextured mold surfaces including the texturing pitch should be small enough for ceramic particles; the mold surface should be sufficiently hard; the lower the surface energy per unit area, the less residues of ceramic particles.

Dynamic Properties of Heart Fragments from Different Regions and Their Synchronization.

The dynamic properties of the heart differ based on the regions that effectively circulate blood throughout the body with each heartbeat. These properties, including the inter-beat interval (IBI) of autonomous beat activity, are retained even in in vitro tissue fragments. However, details of beat dynamics have not been well analyzed, particularly at the sub-mm scale, although such dynamics of size are important for regenerative medicine and computational studies of the heart. We analyzed the beat dynamics in sub-mm tissue fragments from atria and ventricles of hearts obtained from chick embryos over a period of 40 h. The IBI and contraction speed differed by region and atrial fragments retained their values for a longer time. The major finding of this study is synchronization of these fragment pairs physically attached to each other. The probability of achieving this and the time required differ for regional pairs: atrium-atrium, ventricle-ventricle, or atrium-ventricle. Furthermore, the time required to achieve 1:1 synchronization does not depend on the proximity of initial IBI of paired fragments. Various interesting phenomena, such as 1:n synchronization and a reentrant-like beat sequence, are revealed during synchronization. Finally, our observation of fragment dynamics indicates that mechanical motion itself contributes to the synchronization of atria.

Possible associations between palliative care conferences and positive outcomes when performing palliative care for patients with end-stage heart failure: a nationwide cross-sectional questionnaire survey.

Palliative care for end-stage heart failure should be provided by a multidisciplinary team. However, the influence of each occupational category on patients receiving palliative care for end-stage heart failure remains unclear. Thus, this study investigated the relationships between palliative care conferences and positive outcomes of palliative care for end-stage heart failure patients. We sent questionnaires to all cardiology training hospitals authorized by the Japanese Circulation Society (n = 1004); of these, responses from the directors at 554 institutions were analyzed. We divided the responding institutions into two groups according to their implementation of palliative care conferences for patients with end-stage heart failure. The institutions that had held such conferences (n = 223) had a larger number of hospital beds, beds in the cardiovascular department, and patients admitted to the cardiovascular department, compared with institutions that had not held these conferences (n = 321). The usage rates of opioids, non-steroidal anti-inflammatory drugs, and sedatives were significantly higher in institutions that held these conferences. Multivariate analysis revealed that nutritionists and medical social workers had greater involvement in the improvement of mental symptoms and ensuring that patients could stay where they wished, respectively. The presence of palliative care physicians, physical therapists, or pharmacists was associated with multiple positive outcomes. This study indicated that there are possible associations between palliative care conferences and positive outcomes when performing palliative care for patients with end-stage heart failure.

Nationwide Survey of Palliative Care for Patients With Heart Failure in Japan.

BACKGROUND: Palliative care for heart failure (HF) patients is recommended in Western guidelines, so this study aimed to clarify the current status of palliative care for HF patients in Japan.Methods and Results:A survey was sent to all Japanese Circulation Society-authorized cardiology training hospitals (n=1,004) in August 2016. A total of 544 institutions (54%) returned the questionnaire. Of them, 527 (98%) answered that palliative care is necessary for patients with HF. A total of 227 (42%) institutions held a palliative care conference for patients with HF, and 79% of the institutions had <10 cases per year. Drug therapy as palliative care was administered at 403 (76%) institutions; morphine (87%) was most frequently used. Among sedatives, dexmedetomidine (33%) was administered more often than midazolam (29%) or propofol (20%). Regarding the timing of end-of-life care, most institutions (84%) reported having considered palliative care when a patient reached the terminal stage of HF. Most frequently, the reason for the decision at the terminal stage was "difficulty in discontinuing cardiotonics." A major impediment to the delivery of palliative care was "difficulty predicting an accurate prognosis." CONCLUSIONS: This large-scale survey showed the characteristics of palliative care for HF in Japan. The present findings may aid in the development of effective end-of-life care systems.

Design of a nationwide survey on palliative care for end-stage heart failure in Japan.

BACKGROUND: The term palliative care has historically been associated with support for individuals with advanced incurable cancer, so cardiologists and cardiac nurses may be unfamiliar with its principles and practice. However, palliative care is now a part of end-stage heart failure management. We conducted the first nationwide survey to investigate the status of palliative care for heart failure in Japan. METHODS AND RESULTS: A self-reported questionnaire was mailed to all Japanese Circulation Society - authorized cardiology training hospitals (n=1004) in August 2016. The response deadline was December 2016. The survey focused on the following topics: basic information about the facility and multidisciplinary team, patient symptoms for palliative care, positive outcomes after providing palliative care, drug therapy as palliative care for patients with heart failure, advance care planning with patients and their families, and impediments to providing palliative care to patients with heart failure. The results of the survey will be reported in detail elsewhere. CONCLUSIONS: Current guidelines on palliative care do not specifically address what team members should be involved, what drugs should be used, or when palliative care should be started. This survey collected information to improve the quality of palliative care and provide more specialized palliative care within the limits of resources.

Rapid reductive dechlorination of trichloroethene in contaminated ground water using biostimulation agent, BD-1, formulated from canola oil.

A case study of the bioremediation of groundwater contaminated with trichloroethene (TCE) was conducted using the biostimulation agent, BD-1. TCE levels were monitored by gas chromatography-mass spectroscopy. Total organic carbon (TOC) and volatile fatty acids (VFAs) were analyzed to investigate the environmental fate of BD-1. The effects of BD-1 on microbial activity were investigated using 16S rRNA gene-based quantitative polymerase chain reaction (qPCR) analysis. The biodegradation of BD-1 was accompanied by a reduction in TCE, and the initially high TOC levels decreased rapidly as BD-1 was transformed into VFAs. qPCR analysis showed that the genus Dehalobacter became progressively dominant through the experiment. These results suggested that BD-1 might dechlorinate TCE by activating dechlorinating bacteria.

Effects of polymyxin B-immobilized fiber using a rat cecal ligation and perforation model.

We evaluated the efficacy of polymyxin B-immobilized fiber (PMX-F) on organ dysfunction using a rat cecal ligation and perforation (CLP) model. Fifteen-week-old Sprague-Dawley rats (n = 21) were divided into three groups. For a PMX group, n = 7, peritonitis was induced by CLP. After 24 hours from CLP, endotoxin adsorption was performed for 1 hour with a PMX-F column. A sham group, n = 7, external circulation was performed with nonimmobilized fiber column. A control group, n = 7, were sacrificed 25 hours after CLP (no hemoperfusion performed). The changes in interleukin (IL)-6, IL-10, tumor necrosis factor (TNF)-alpha and plasminogen activator inhibitor (PAI)-1 were measured. The lungs, liver, and kidneys were stained with hematoxylin and eosin and anti-PAI-1 antibodies. Terminal uridine-triphosphate nick-end labeling assay was performed to evaluate apoptosis. The PMX group showed a tendency to decrease in blood levels of IL-6 and PAI-1 compared with the sham group. Anti-PAI-1 antibody staining was seen in the lungs of the control and sham groups. The PMX group showed significantly decreased apoptotic cells in renal tubule cells compared with sham and control groups. We conclude that PMX-F may have inhibited PAI-1 expression in the lungs and decreased apoptosis of renal tubule cells.

Quantitative analysis of long-range interactions between adsorbed dipolar molecules on Cu(111).

Highly dispersed superstructures of a dipolar iridium complex are formed on a Cu(111) surface. We show that the dilute superstructures with density-controlled intermolecular separations are stabilized by the strong and long-range repulsive intermolecular interactions. The repulsive intermolecular interactions are quantitatively evaluated by using low-temperature scanning tunneling microscopy, which are characterized by the surface-enhanced dipole-dipole interactions.

Hypersensitivity in DNA mismatch repair-deficient colon carcinoma cells to DNA polymerase reaction inhibitors.

We studied the cytotoxic effects of various DNA replication inhibitors on MMR-deficient and -proficient colon carcinoma cell lines. DNA polymerase (pol) inhibitors including aphidicolin and gemcitabine, and hydroxyurea were more toxic (1.7 to 2.8-fold) to hMLH1-deficient HCT116 than to hMLH1-proficient HCT116+ch3. Similarly, pol inhibitors were more toxic to hMSH2-deficient LoVo than to hMSH2-proficient LoVo+ch2. In contrast, DNA topoisomerase I inhibitors, such as CPT-11, SN-38, and topotecan, were more toxic to MMR-proficient cells. Our results suggest that MMR-deficient colon carcinoma cells are hypersensitive to inhibitors of the pol reaction.