Segmentation of process-related contaminations on two-piece abutments using pixel-based machine learning: a new quantification approach?

PURPOSE: A reference method for quantifying contaminations on two-piece abutments manufactured using CAD/CAM has not yet been established. In the present in vitro study, a pixel--based machine learning (ML) method for detecting contamination on customized two-piece abutments was investigated and embedded in a semiautomated quantification pipeline. MATERIALS AND METHODS: Forty-nine CAD/CAM zirconia abutments were fabricated and bonded to a prefabricated titanium base. All samples were analyzed for contamination by scanning electron microscopy (SEM) imaging followed by pixel--based ML and thresholding (SW) for contamination detection; quantification was performed in the postprocessing pipeline. Wilcoxon signed-rank test and Bland-Altmann plot were applied to compare both methods. The contaminated area fraction was recorded as a percentage. RESULTS: There was no statistically significant difference between the percentages of contamination areas (median = 0.004) measured with ML (median = 0.008) and with SW (median = 0.012), asymptotic Wilcoxon test: P = 0.22. The Bland-Altmann plot demonstrated a mean difference of -0.006% (95% confidence interval [CI] from -0.011% to 0.0001%) with increased values from a contamination area fraction of > 0.03% for ML. CONCLUSION: Both segmentation methods showed comparable results in evaluating surface cleanliness; pixel-based ML is a promising assessment tool for detecting external contaminations on zirconia abutments. Further studies are required to investigate the clinical performance of this tool.

Natural history of echocardiographic changes in atrial fibrillation: A case-controlled study of longitudinal remodeling.

BACKGROUND: Atrial fibrillation (AF) can be a cause and consequence of cardiac remodeling. The natural history of remodeling associated with AF is incompletely described. OBJECTIVE: The purpose of this study was to describe the frequency and timing of AF-associated echocardiographic changes. METHODS: Patients within the Duke University Health System with ≥2 transthoracic echocardiograms (TTEs) performed between 2005 and 2018 were evaluated. Patients with AF and normal baseline TTEs were matched to patients without AF on year of TTE, age, and CHA2DS2-VASc score. Frequency and timing of changes in chamber size, ventricular function, mitral regurgitation, and all-cause mortality were compared over 5 years of follow-up. RESULTS: The cohort included 3299 patients with AF at baseline and 7613 controls without AF. Normal baseline TTEs were acquired from 730 of patients with AF; 727 of these patients were matched to controls without AF. Patients with AF had higher rates of left atrial enlargement (hazard ratio [HR] 1.53; 95% confidence interval 1.27-1.85; P < .001), left ventricular (LV) systolic dysfunction (HR 1.80; 95% confidence interval 1.00-3.26; P = .045), LV diastolic dysfunction (HR 1.51; 95% confidence interval 1.08-2.10; P = .01), and moderate or greater mitral regurgitation (HR 2.09; 95% confidence interval 1.27-3.43; P = .003) than did controls. Atrial enlargement, systolic dysfunction, and mitral regurgitation surpassed the rates seen in controls within 6-12 months, whereas differences in diastolic dysfunction emerged at 24 months. There were no differences in ventricular sizes or mortality. CONCLUSION: AF is associated with higher rates of left atrial enlargement, LV systolic and diastolic dysfunction, and mitral regurgitation that typically manifest within 6-24 months of diagnosis. The natural history of cardiac remodeling in patients with AF may inform treatment decisions and facilitate patient-tailored care.

Influence of exposure of customized dental implant abutments to different cleaning procedures: an in vitro study using AI-assisted SEM/EDS analysis.

PURPOSE: Dental implant abutments are defined as medical devices by their intended use. Surfaces of custom-made CAD/CAM two-piece abutments may become contaminated during the manufacturing process in the dental lab. Inadequate reprocessing prior to patient care may contribute to implant-associated complications. Risk-adapted hygiene management is required to meet the requirements for medical devices. METHODS: A total of 49 CAD/CAM-manufactured zirconia copings were bonded to prefabricated titanium bases. One group was bonded, polished, and cleaned separately in dental laboratories throughout Germany (LA). Another group was left untreated (NC). Five groups received the following hygiene regimen: three-stage ultrasonic cleaning (CP and FP), steam (SC), argon-oxygen plasma (PL), and simple ultrasonic cleaning (UD). Contaminants were detected using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) and segmented and quantified using interactive machine learning (ML) and thresholding (SW). The data were statistically analysed using non-parametric tests (Kruskal-Wallis test, Dunn's test). RESULTS: Significant differences in contamination levels with the different cleaning procedures were found (p ≤ 0.01). The FP-NC/LA groups showed the most significant difference in contamination levels for both measurement methods (ML, SW), followed by CP-LA/NC and UD-LA/NC for SW and CP-LA/NC and PL-LA/NC for ML (p ≤ 0.05). EDS revealed organic contamination in all specimens; traces of aluminum, silicon, and calcium were detected. CONCLUSIONS: Chemothermal cleaning methods based on ultrasound and argon-oxygen plasma effectively removed process-related contamination from zirconia surfaces. Machine learning is a promising assessment tool for quantifying and monitoring external contamination on zirconia abutments.

Electronic health record characterization and outcomes of heart failure with preserved ejection fraction.

BACKGROUND: Electronic health record (EHR)-based identification of heart failure with preserved ejection fraction (HFpEF) in the clinical setting may facilitate screening for clinical trials by improving the understanding of its epidemiology and outcomes; yet, previous data have yielded variable results. We sought to characterize groups identified with HFpEF by different EHR screening strategies and their associated long-term outcomes across a large and diverse population. METHODS: We retrospectively analyzed 116,499 consecutive patients from an academic referral center who underwent echocardiography, and 9,263 patients who underwent echocardiography within 6 months of right heart catheterization (RHC), between 2008 and 2018. EHR-based screening strategies identified patients with HFpEF using 1) International Classification of Diseases (ICD)-9/10 codes, 2) H2FpEF score ≥6 and ejection fraction (EF) ≥50%, or 3) RHC wedge pressure ≥15 mmHg and EF ≥50%, when available. Primary outcomes were 1) cumulative incident heart failure hospitalization (HFH), and 2) death, over 10 years. RESULTS: There were 33,461 (29%) patients who met either ICD or H2FpEF-HFpEF definition, of whom 5,310 (16%) met both criteria. Compared to ICD-HFpEF, patients with H2FpEF-HFpEF were more likely older (median age 72 vs 67), White (78% vs 64%), and had atrial fibrillation (97% vs 41%). Among those also with RHC, 6,353 (69%) patients met any HFpEF criteria, of whom only 783 (12%) satisfied all three criteria. Female sex was more common among RHC-HFpEF (55%) compared to other methods (H2FpEF-HFpEF, 47%; ICD-HFpEF, 43%). Atrial fibrillation was substantially higher among HFpEF identified by the H2FpEF score (97%) compared to other methods (49% for ICD and 47% for RHC). Across HFpEF screening methods, 10-year cumulative incidence rates for HFH was 32% to 45% for echocardiography only and 43% to 52% for echocardiography and RHC populations; 10-year risk of death was 54% to 56% for echocardiography only and 52% to 57% for echocardiography and RHC populations. CONCLUSIONS: Different EHR-based HFpEF definitions identified cohorts with modest overlap and varying baseline characteristics. Yet, long-term risk for HFH and death were similarly high for cohorts identified among both populations undergoing echocardiography only or echocardiography and RHC. These data aid in identifying relevant subgroups in clinical trials of HFpEF.

Continuous Monitoring of Heart Rate Variability and Clinical Outcomes in Patients with Implantable Cardioverter Defibrillators.

While heart rate variability (HRV) is an established marker of cardiovascular health, the extent to which continuously measured HRV changes over time and the relationship between these changes and clinical outcomes are less clear. We performed a health system analysis of 225 patients implanted with a cardiac defibrillator or cardiac resynchronization device (CRT) with continuous HRV recording capabilities. We found that continuously measured HRV changed modestly over 2 years. Low baseline HRV, which is associated with low parasympathetic tone and/or increases in sympathetic tone, pertains a worse clinical prognosis as reflected by a significant association with all-cause hospitalization. Observed changes in HRV over 6-months of follow-up were not associated with subsequent outcomes.

Electrocardiographic parameters associated with pacemaker induced cardiomyopathy.

BACKGROUND: Chronic right ventricular (RV) pacing can induce left ventricular (LV) dyssynchrony and cause pacemaker induced cardiomyopathy (PiCM). Identifying which patients are at risk for PiCM is limited. METHODS: Patients receiving RV-only permanent pacemakers (PPMs) at Duke University Medical Center between 2011 and 2017 who had normal baseline ejection fractions (EFs) were identified. Patients who developed a subsequent decrease in EF, died, or underwent cardiac resynchronization therapy, left ventricular assist device, or heart transplant without a competing cause were considered as the primary endpoint. Pre-PPM and post-PPM electrocardiograms (ECGs) were analyzed to extract scalar measurements including the lead one ratio (LOR) as well as advanced-ECG (A-ECG) features to identify predictors of PiCM. Traditional and penalized Cox regression were used to identify variables predictive of the primary endpoint. RESULTS: Pre-PPM ECGs were evaluated for 404 patients of whom 140 (35%) experienced the primary endpoint. Predictors included female sex (hazard ratio [HR] 1.14), a T' wave in V6 (HR 1.31), a P' wave in aVL (HR 0.88), and estimated glomerular filtration rate (HR 0.88). Post-PPM ECGs were evaluated for 228 patients for whom 94 (41%) experienced the primary endpoint. Predictors included female sex (HR 0.50), age (HR 1.06), and a history of congestive heart failure (HR 1.63). Neither LOR nor A-ECG parameters were strong predictors of the primary endpoint. CONCLUSIONS: Baseline and paced ECG data provide limited insight into which patients are at high risk for developing PiCM.

Characteristics and Outcomes of Suspected Digoxin Toxicity and Immune Fab Treatment Over the Past Two Decades-2000-2020.

The role of digoxin in clinical practice has narrowed over time. Data on digoxin toxicity trends and outcomes are variable and lack granularity for treatment outcomes. This study aimed to address data gaps in digoxin toxicity trends and outcomes in patients treated with or without digoxin immune fab (DIF). This single-center analysis examined patients with signs/symptoms concerning digoxin toxicity, defined as hospital admission or emergency department visit with elevated digoxin serum concentrations (>2 ng/ml) and/or a primary diagnosis code of digoxin toxicity and/or DIF order. Between 2000 and 2020, 727 patients were identified with signs concerning for digoxin toxicity with a mortality rate of 12.7% during admission and 42.7% at 1 year. DIF was ordered in 9% of cases. Incidence of digoxin toxicity per 1,000 patients with a digoxin prescription and frequency of DIF treatment fluctuated over time without a clear trend toward increase or reduction. DIF-treated patients demonstrated a heavier co-morbidity burden and lower presenting heart rates (median 53 [39.5 to 69.5] vs 77 [64.0 to 91.5] beats/min, p <0.001), worse renal function (median estimated glomerular filtration rate, 30.3 [14.8 to 48.6] vs 40.0 [24.2 to 61.2] ml/min/1.73 m2, p = 0.013), and higher potassium (median 4.5 [4.0 to 5.3] vs 4.3 [3.9 to 4.8] mEq/L, p = 0.022). Compared with a matched cohort, DIF-treated patients experienced a nonsignificant, numerically lower in-hospital mortality (8.2% vs 15.8%, p = 0.199) and 30-day all-cause hospitalization (14.3% vs 24.7%, p = 0.112) and similar 6-month and 1-year hospitalization and mortality. In conclusion, digoxin toxicity remains a pertinent public health issue despite reduction in digoxin utilization. DIF therapy is used in a medically complex population with a high-acuity illness at presentation and is associated with nonsignificant trends toward reduced in-hospital mortality and early readmission that are attenuated over time.

Clinical trajectory of patients with a worsening heart failure event and reduced ventricular ejection fraction.

BACKGROUND: Recent data suggest that patients with heart failure with reduced ejection fraction (HFrEF) and worsening heart failure (WHF) have potential for greater benefit from newer HF therapies. We investigated characteristics and outcomes of patients with HFrEF and WHF by severity of left ventricular dysfunction. METHODS: We identified patients with chronic symptomatic HFrEF (left ventricular ejection fraction [LVEF] ≤35%) and evidence of WHF (emergency department visit or hospitalization for acute HF within 12 months of index echocardiogram) treated at Duke University between 1/2009 and 12/2018. Patients were stratified by LVEF≤25% or 26% to35%. Cox models were used to estimate cause-specific hazard ratios and 5-year event incidence of death and hospitalization across the range of LVEF. RESULTS: Of 2823 patients with HFrEF and WHF, 1620 (57.4%) had an LVEF≤25% and 1203 (42.6%) had an LVEF 26% to35%. Compared to patients with LVEF 26% to35%, those with LVEF≤25% were younger and more commonly men with a lower cardiovascular comorbidity burden. Patients with LVEF≤25% were less commonly on beta blockers (85.9% vs 90.5%) but more commonly treated with mineralocorticoid receptor antagonists (49.3% vs 41.1%) and implantable defibrillators (41.3% vs 28.2%). Patients with LVEF≤25% had significantly higher hazards for death (HR 1.24 [95% CI 1.11 - 1.38]), all-cause hospitalization (HR 1.21 [95% CI 1.10 - 1.33]), and HF hospitalization (HR 1.25 [95% CI 1.1 - 1.38]) through 5-years. CONCLUSIONS: More than half of patients with chronic HFrEF and WHF have severe LV dysfunction. Important differences in comorbidities, HF therapies, and outcomes exist between those with LVEF≤25% and those with LVEF 26% to35%.

Characteristics and Outcomes of Patients With Heart Failure With Reduced Ejection Fraction After a Recent Worsening Heart Failure Event.

Background Contemporary trials of patients with heart failure with reduced ejection fraction (HFrEF) required a recent worsening heart failure (WHF) event for inclusion. We aimed to describe characteristics and outcomes of patients with HFrEF and a recent WHF event at a large tertiary referral center. Methods and Results We identified adult patients with chronic symptomatic HFrEF (ejection fraction ≤35%) treated at Duke University between January 1, 2009, and December 31, 2018, and applied a set of exclusion criteria to generate a cohort similar to those enrolled in contemporary heart failure trials. Patients were stratified by presence or absence of a recent WHF event, defined as an emergency department visit for heart failure or hospitalization for heart failure in the prior 12 months. Characteristics and outcomes including death and hospitalization were assessed. Of 3867 patients with HFrEF meeting study criteria, 2823 (73.0%) had a WHF event in the prior 12 months. Compared with patients without a WHF event, those with a WHF event were more likely to be under-represented racial and ethnic groups and had lower ejection fraction, a greater burden of comorbidities, and more echocardiographic evidence of cardiac dysfunction. Despite higher use of guideline-directed therapies, patients with a WHF event had higher rates of death (hazard ratio, 2.30; 95% CI, 2.01-2.63), all-cause hospitalization (hazard ratio, 1.56; 95% CI, 1.42-1.71), and heart failure hospitalization (hazard ratio, 1.59; 95% CI, 1.44-1.75) through 5 years compared with those without a recent WHF event. Conclusions WHF events are common in patients with HFrEF and are associated with more advanced disease. Patients with recent WHF have high rates of death and hospitalization, underscoring the need for novel therapies in this large subgroup of patients with HFrEF.

Coalition for Global Clinical Surgical Education: The Alliance for Global Clinical Training.

OBJECTIVE: Assessment of the effect of the collaborative relationship between the high-income country (HIC) surgical educators of the Alliance for Global Clinical Training (Alliance) and the low-income country surgical educators at the Muhimbili University of Health and Allied Sciences/Muhimbili National Hospital (MUHAS/MNH), Dar Es Salaam, Tanzania, on the clinical global surgery training of the HIC surgical residents participating in the program. DESIGN: A retrospective qualitative analysis of Alliance volunteer HIC faculty and residents' reports, volunteer case lists and the reports of Alliance academic contributions to MUHAS/MNH from 2012 to 2017. In addition, a survey was circulated in late 2016 to all the residents who participated in the program since its inception. RESULTS: Twelve HIC surgical educators provided rotating 1-month teaching coverage at MUHAS/MNH between academic years 2012 and 2017 for a total of 21 months. During the same time period 11 HIC residents accompanied the HIC faculty for 1-month rotations. HIC surgery residents joined the MUHAS/MNH Department of Surgery, made significant teaching contributions, performed a wide spectrum of "open procedures" including hand-sewn intestinal anastomoses. Most had had either no or limited previous exposure to hand-sewn anastomoses. All of the residents commented that this was a maturing and challenging clinical rotation due to the complexity of the cases, the limited resources available and the ethical and emotional challenges of dealing with preventable complications and death in a resource constrained environment. CONCLUSIONS: The Alliance provides an effective clinical global surgery rotation at MUHAS/MNH for HIC Surgery Departments wishing to provide such an opportunity for their residents and faculty.

Prognostic value of the cadmium-zinc-telluride camera: A comparison with a conventional (Anger) camera.

BACKGROUND: New multipinhole cadmium-zinc-telluride (CZT) cameras allow for faster imaging and lower radiation doses for single photon emission computed tomography (SPECT) studies, but assessment of prognostic ability is necessary. METHODS AND RESULTS: We collected data from all myocardial SPECT perfusion studies performed over 15 months at our institution, using either a CZT or conventional Anger camera. A Cox proportional hazards model was used to assess the relationship between camera type, imaging results, and either death or myocardial infarction (MI). Clinical variables including age, sex, body mass index (BMI), and historical risk factors were used for population description and model adjustments. We had 2,088 patients with a total of 69 deaths and 65 MIs (122 events altogether). A 3% increase in DDB (difference defect burden) represented a 12% increase in the risk of death or MI, whereas a 3% increase in rest defect burden or stress defect burden represented an 8% increase; these risks were the same for both cameras (P > .24, interaction tests). CONCLUSIONS: The CZT camera has similar prognostic values for death and MI to conventional Anger cameras. This suggests that it may successfully be used to decrease patient dose.

The Power of Humility.

Consistently high-performing health systems and hospitals have one key trait in common: humility.