Valvular calcium load assessment for predicting postprocedural paravalvular leakage: a comparison between surgical aortic valve replacement versus transcatheter implantation

Background

Calcification of native aortic valve is a well known variable causing paravalvular leakage (PVL) following transcatheter aortic valve implantation (TAVI). However, there is currently no evidence to support the fact that patients with high calcium load could be better treated with surgical aortic valve replacement (SAVR).

Purpose

To assess the utility of preoperative assessment of valvular calcium load through computed tomography in patients affected by severe aortic valve stenosis undergoing SAVR or TAVI.

Methods

Between June 2016 and June 2018, 109 candidates for isolated SAVR through minimal invasive access underwent preoperative contrast enhanced multidetector computed tomography (MDCT) for the assessment of valve and aortic calcifications. Calcium load was quantitatively measured using a dedicated software in three regions on interest (aortic valve [AV], left ventricular outflow tract [LVOT] and device landing zone [DLZ], which is the sum of the earlier 2). Clinical, echocardiographic, and MDCT variables were collected and compared to a sample population of 107 patients that underwent TAVI (87 transfemoral, 20 transapical) for native aortic valve stenosis in the same period of time, in the same institution. A univariate and multivariate logistic regression analysis were performed on the whole study population to assess risk factors for the onset of postoperative PVL (any grade, defined as ≥ mild) at discharge.

Results

The two study groups were significantly different in terms of age (71.9±5 in SAVR; 81.5±6 in TAVI), gender (36% female in SAVR vs 51% in TAVI), Euroscore II (1.9%±0.8 in SAVR; 4.8%±2.7 in TAVI), annulus perimeter (79.5mm±8.2 in SAVR; 61.8mm±30.5 in TAVI), baseline ejection fraction (57%±8 in SAVR; 51%±12 in TAVI) and severe pulmonary hypertension (2%±13 in SAVR; 26%±44 in TAVI). Calcium load was not different between groups (DLZ 1066 mm3±716 vs 955mm3±639; total calcium in AV 987 mm3±678 vs 879 mm3±601; total calcium in LVOT 78 mm3±130 vs 77 mm3±100). 30-days-mortality was 1.8% in SAVR and 5.6% in TAVI group (p=0.17). At discharge, incidence of all grades PVL was 5.5% in SAVR (0.9% trace, 3.6% mild, 0.9% moderate) and 41% in TAVI group (12.1% trace, 25.2% mild, 3.7% moderate) (p<0.05). On logistic regression on the whole study population, DLZ calcium (OR 1.1, 95% CI 1–1.2 for 100 mm3, p=0.003) and the use of TAVI (OR 24, 95% CI 7.7–78, p<0.001) were identified as independently associated with the onset of PVL.

Conclusions

Aortic valve calcifications are a risk factor for the onset of PVL for both TAVI and SAVR. Nevertheless, the risk increases considerably with the use of TAVI. A deeper anatomical analysis of preoperative MDCT could improve the treatment selection and the outcome of patients affected by aortic valve stenosis.

Funding Acknowledgement

Type of funding source: None

Towards a more accurate quantitative assessment of seasonal Cryptosporidium infection risks in surface waters using species and genotype information

Many Cryptosporidium species/genotypes are not considered infectious to humans, and more realistic estimations of seasonal infection risks could be made using human infectious species/genotype information to inform quantitative microbial risk assessments (QMRA). Cryptosporidium oocyst concentration and species/genotype data were collected from three surface water surveillance programs in two river basins [South Nation River, SN (2004-09) and Grand River, GR (2005-13)] in Ontario, Canada to evaluate seasonal infection risks. Main river stems, tributaries, agricultural drainage streams, water treatment plant intakes, and waste water treatment plant effluent impacted sites were sampled. The QMRA employed two sets of exposure data to compute risk: one assuming all observed oocysts were infectious to humans, and the other based on the fraction of oocysts that were C. hominis and/or C. parvum (dominant human infectious forms of the parasite). Viability was not considered and relative infection risk was evaluated using a single hypothetical recreational exposure. Many sample site groupings for both river systems, had significant seasonality in Cryptosporidium occurrence and concentrations (p ≤ 0.05); occurrence and concentrations were generally highest in autumn for SN, and autumn and summer for GR. Mean risk values (probability of infection per exposure) for all sites combined, for each river system, were roughly an order of magnitude lower (avg. of SN and GR 5.3 × 10^-5) when considering just C. parvum and C. hominis oocysts, in relation to mean infection risk (per exposure) assuming all oocysts were infectious to humans (5.5 × 10^-4). Seasonality in mean risk (targeted human infectious oocysts only) was most strongly evident in SN (e.g., 7.9 × 10^-6 in spring and 8.1 × 10^-5 in summer). Such differences are important if QMRA is used to quantify effects of water safety/quality management practices where inputs from a vast array of fecal pollution sources can readily occur. Cryptosporidium seasonality in water appears to match the seasonality of human infections from Cryptosporidium in the study regions. This study highlights the importance of Cryptosporidium species/genotype data to help determine surface water pollution sources and seasonality, as well as to help more accurately quantify human infection risks by the parasite.

Campylobacter spp. Prevalence and Levels in Raw Milk: A Systematic Review and Meta-Analysis

Campylobacteriosis is the leading bacterial gastrointestinal disease internationally, contributing significantly to the enteric illness burden. Cases have been associated with the consumption of raw milk, a behavior that has garnered attention recently. Estimates of the prevalence and levels of Campylobacter spp. in raw milk are lacking, which hinders risk assessment attempts. This article is a systematic review and meta-analysis of reported prevalence and levels of zoonotic Campylobacter spp. in the raw milk of cows, goats, and sheep in Canada, the United States, Europe, Australia, and New Zealand. The relevant literature was reviewed, and trained reviewers examined the results for inclusion of articles in the meta-analysis. Relevant data (prevalence and/or level of Campylobacter in raw milk, country of origin, animal species, sample source, Campylobacter species identified, etc.) were extracted, and a meta-analysis was performed in Stata v. 12 (Metaprop command). The weighted mean prevalence of Campylobacter spp. in raw milk samples was 1.18%. Subgroup analyses were conducted to examine how prevalence varied by study characteristics, with the highest prevalence values in studies from the United Kingdom (by country, 6.4%), about cows (by animal species, 1.3%), and including samples taken from inline filters (by sample source, 1.75%) and in studies that included species that are not pathogenic to humans (by Campylobacter species, 1.14%). Two articles each included a single Campylobacter level, 0.16 ± 0.3 and approximately 0.047 most probable number per ml. Despite a relatively low prevalence, consumption of raw milk is inherently risky because no treatment has been used to inactivate pathogens. This potential risk further supports maintaining regulations to limit the sales of raw milk.

Distribution of Salmonella in Humans, Production Animal Operations and a Watershed in a FoodNet Canada Sentinel Site

Salmonella is an important human pathogen, and production animals as well as water are known potential sources. This study helped provide insight into the epidemiology of Salmonella by comparing Salmonella strains found in humans to those detected in production animals and water in the same geographic area and time frame. Salmonella was found in 55% of broiler, 30% of swine, 13% of dairy, and 10% of beef manure samples and 23% of water samples. At the farm level, Salmonella was found on 93% of broiler, 81% of swine, 32% of beef and 30% of dairy farms. Salmonella strains of importance to public health were found in all sources tested; however, they appeared to be more common in the broilers. A number of the farms in this study were mixed farms, in that they had more than one production animal species on the farm. At both the sample and farm levels, beef-only farms had a significantly lower Salmonella prevalence (5% and 7%, respectively) than beef farms with additional production animal species (e.g. poultry) (12% and 42%, respectively) (P ≤ 0.05). Additionally, a number of mixed farms had more than one commodity sampled for this study and similar Salmonella strains by phage type and PFGE were found in the poultry and the other sampled commodity on the farm. This information can help inform the evidence base needed to help target interventions and modify best practices in production agriculture.

First experience with the new Sorin Crown PRT bioprosthetic aortic valve: early postoperative outcome and hemodynamic performance in 90 patients

AIM

The Crown PRT (The Phospholipid Reduction Treatment) is a new stent bovine bioprosthesis for aortic valve replacement (AVR). Aim of this paper is to report the postoperative clinical and hemodynamic results after ninety consecutive implants.

METHODS

After receiving CE mark in July 2014, two European university centers implanted the new Crown PRT (Sorin Group, Burnaby, Canada) for the first time. Up to now, ninety patients underwent aortic valve replacement, in isolated or combined procedures, for aortic stenosis or insufficiency. Intraoperative transesophageal echocardiogram was used to assess the prosthesis's function. In hospital outcomes and echocardiographic parameters were recorded.

RESULTS

Age and Log Euroscore were 71.8±7.9 years and 10.2%±4.5 respectively. In-hospital mortality for isolated AVR was 0%; one patient died after a multiple procedure (overall 30-days mortality 1.1%). No adverse device effects were recorded. Intensive Care Unit stay was 2±5.8 days. At discharge, echocardiogram showed no paravalvular leaks and normal postoperative gradients.

CONCLUSION

Our starting results showed that the Crown PRT is safe and reliable, with excellent hemodynamic performance. Further clinical results with a larger population and long term follow-up are needed to assess the versatility and the durability of this new device.

Detection and prevalence of verotoxin-producing Escherichia coli O157 and non-O157 serotypes in a Canadian watershed

Verotoxin-producing Escherichia coli (VTEC) strains are the cause of food-borne and waterborne illnesses around the world. Traditionally, surveillance of the human population as well as the environment has focused on the detection of E. coli O157:H7. Recently, increasing recognition of non-O157 VTEC strains as human pathogens and the German O104:H4 food-borne outbreak have illustrated the importance of considering the broader group of VTEC organisms from a public health perspective. This study presents the results of a comparison of three methods for the detection of VTEC in surface water, highlighting the efficacy of a direct VT immunoblotting method without broth enrichment for detection and isolation of O157 and non-O157 VTEC strains. The direct immunoblot method eliminates the need for an enrichment step or the use of immunomagnetic separation. This method was developed after 4 years of detecting low frequencies (1%) of E. coli O157:H7 in surface water in a Canadian watershed, situated within one of the FoodNet Canada integrated surveillance sites. By the direct immunoblot method, VTEC prevalence estimates ranged from 11 to 35% for this watershed, and E. coli O157:H7 prevalence increased to 4% (due to improved method sensitivity). This direct testing method provides an efficient means to enhance our understanding of the prevalence and types of VTEC in the environment. This study employed a rapid evidence assessment (REA) approach to frame the watershed findings with watershed E. coli O157:H7 prevalences reported in the literature since 1990 and the knowledge gap with respect to VTEC detection in surface waters.

Considering the risk of infection by cryptosporidium via consumption of municipally treated drinking water from a surface water source in a Southwestern Ontario community

Through the use of case-control analyses and quantitative microbial risk assessment (QMRA), relative risks of transmission of cryptosporidiosis have been evaluated (recreational water exposure vs. drinking water consumption) for a Canadian community with higher than national rates of cryptosporidiosis. A QMRA was developed to assess the risk of Cryptosporidium infection through the consumption of municipally treated drinking water. Simulations were based on site-specific surface water contamination levels and drinking water treatment log₁₀ reduction capacity for Cryptosporidium. Results suggested that the risk of Cryptosporidium infection via drinking water in the study community, assuming routine operation of the water treatment plant, was negligible (6 infections per 10¹³ persons per day--5th percentile: 2 infections per 10¹⁵ persons per day; 95th percentile: 3 infections per 10¹² persons per day). The risk is essentially nonexistent during optimized, routine treatment operations. The study community achieves between 7 and 9 log₁₀ Cryptosporidium oocyst reduction through routine water treatment processes. Although these results do not preclude the need for constant vigilance by both water treatment and public health professionals in this community, they suggest that the cause of higher rates of cryptosporidiosis are more likely due to recreational water contact, or perhaps direct animal contact. QMRA can be successfully applied at the community level to identify data gaps, rank relative public health risks, and forecast future risk scenarios. It is most useful when performed in a collaborative way with local stakeholders, from beginning to end of the risk analysis paradigm.

A risk assessment model to evaluate the role of fecal contamination in recreational water on the incidence of cryptosporidiosis at the community level in Ontario

A quantitative microbial risk assessment model was developed to simulate the role of recreational water contact in the transmission of cryptosporidiosis in a model Ontario community. Stochastic simulations were based on plausible modes of contamination of a pool (literature derived), river (site-specific), and recreational lakes (literature derived). The highest estimated risks of infection were derived from the (highly contaminated) recreational lake scenario, considered the upper end for risk of infection for both children (10 infections per 1,000 swims [5 per thousand: two infections per 1,000 swims; 95 per thousand: three infections per 100 swims]) and adults (four infections per 1,000 swims [5 per thousand: four infections per 1,000 swims; 95 per thousand: one infection per 100 swims]). Simulating the likely Cryptosporidium oocyst concentration in a lane pool that a child would be exposed to following a diarrheal fecal release event resulted in the third highest mean risk of infection (four infections per 10,000 swims [5 per thousand: three infections per 100,000; 95 per thousand: 10 infections per 10,000 swims]). The findings from this study illustrate the need for systematic and standardized research to quantify Cryptosporidium oocyst levels in Canadian public pools and recreational beaches. There is also a need to capture the swimming practices of the Canadian public, including most common forms and frequency measures. The study findings suggest that swimming in natural swim environments and in pools following a recent fecal contamination event pose significant public health risks. When considering these risks relative to other modes of cryptosporidiosis transmission, they are significant.

Exploring historical Canadian foodborne outbreak data sets for human illness attribution

Human illness attribution has been recently recognized as an important tool to better inform food safety decisions. Analysis of outbreak data sets has been used for that purpose. This study was conducted to explore the usefulness of three comprehensive Canadian foodborne outbreak data sets covering 30 years for estimating food attribution in cases of gastrointestinal illness, providing Canadian food attribution estimates from a historical perspective. Information concerning the microbiological etiology and food vehicles recorded for each outbreak was standardized between the data sets. The agent-food vehicle combinations were described and analyzed for changes over time by using multiple correspondence analysis. Overall, 6,908 foodborne outbreaks were available for three decades (1976 through 2005), but the agent and the food vehicle were identified in only 2,107 of these outbreaks. Differences between the data sets were found in the distribution of the cause, the vehicle, and the location or size of the outbreaks. Multiple correspondence analysis revealed an association between Clostridium botulinum and wild meat and between C. botulinum and seafood. This analysis also highlighted changes in food attribution over time and generated the most up-to-date food attribution values for salmonellosis (29% of cases associated with produce, 15% with poultry, and 15% with meat other than poultry, pork, and beef), campylobacteriosis (56% of cases associated with poultry and 22% with dairy products other than fluid milk), and Escherichia coli infection (37% of cases associated with beef, 23% with cooked multi-ingredient dishes, and 11% with meat other than beef, poultry, and pork). Because of the inherent limitations of this approach, only the main findings should be considered for policy making. The use of other human illness attribution approaches may provide further clarification.

Water consumption habits of a south-western Ontario community

A cross-sectional telephone survey (n = 2,332) was performed to better understand the drinking water consumption patterns among residents in Waterloo Region, Ontario, Canada. We investigated the daily volume of water consumed (including tap and bottled) and factors related to that consumption. In addition, we investigated the daily volume of cold tap water consumed by those respondents who consumed no bottled water and the factors that influence this consumption. Among study respondents, 51% exclusively drank tap water, 34% exclusively drank bottled water and 14.5% drank both, with 10 to 75% of all cold water consumed in the previous day being bottled. The mean volume of water consumed in a day (including bottled and tap water) was 1.39 l. Among those who reported to exclusively consume tap water, the mean daily volume of tap water consumed was 1.45 l. The daily amount of cold water consumed in a day was lower for older respondents, more markedly for men than women. More educated respondents consumed more water during the day. Roughly 45% of households reported that they used a carbon filter to treat their water. Roughly 5% of respondents used advanced home treatment devices, including ultraviolet light, reverse osmosis, ozonation or distillation.

Burden of acute gastrointestinal illness in Canada, 1999-2007: interim summary of NSAGI activities

INTRODUCTION

The National Studies on Acute Gastrointestinal Illness (NSAGI) initiative was designed to generate baseline period prevalence rates of self-reported AGI in communities across Canada, assess the burden associated with AGI, and quantify the under-reporting of AGI in Canada's national enteric disease reporting systems.

METHODS

Methods utilized included population surveys administered randomly via telephone services. Three population surveys in three locations within Canada included over 10,000 residents. Questions pertained to recent symptoms as well as socio-demographic factors, use of the health care system and missed work or school due to illness.

RESULTS

In summary of published results, there are an estimated 1.3 episodes of AGI per person-year and an estimated 10-47, 13-37 and 23-49 cases in the community for every case of verotoxigenic Escherichia coli, Salmonella and Campylobacter, respectively, captured within the national surveillance system. AGI represents an annual per capita cost of $115 CAD.

DISCUSSION

The work of NSAGI highlights the significant burden and impact of AGI in the Canadian population. These results will also be incorporated into the current work at the World Health Organization (WHO) to estimate the global burden of food related illnesses.

Risk factors for Salmonella typhimurium DT104 and non-DT104 infection: a Canadian multi-provincial case-control study

To identify risk factors for sporadic Salmonella Typhimurium definitive phage-type 104 (DT104) and non-DT104 diarrhoeal illness in Canada, we conducted a matched case-control study between 1999 and 2000. Cases were matched 1:1 on age and province of residence. Multivariate analysis suggested that recent antibiotic use [odds ratio (OR) 5.2, 95% confidence interval (CI) 1.8-15.3], living on a livestock farm (OR 4.9, 95% CI 1.9-18.9), and recent travel outside Canada (OR 4.1, 95% CI 1.2-13.8) are independent risk factors for DT104 illness. Similar analyses suggested that recent travel outside North America is a sizable risk factor for non-DT104 illness (OR 66.8, 95% CI 6.7-665.3). No food exposure was a risk factor in either analysis. Educating health-care providers and the public about appropriate antibiotic use and antimicrobial resistance is important. Appropriate administration of antibiotics to livestock, particularly cattle, and hygienic measures such as handwashing after contact with farm animals may reduce risk. Travel represents an important and probably underestimated risk factor for sporadic illness with S. Typhimurium. Improved national surveillance and detailed investigation of travel-related illness are required.