Medium-term storage of calf beddings affects bacterial community and effectiveness to inactivate zoonotic bacteria

Land-spreading of animal faecal wastes -such as animal beddings- can introduce zoonotic enteropathogens into the food system environment. The study evaluated the effectiveness of animal beddings naturally contaminated by calf manure to reduce E. coli O157:H7 or Salmonella enterica. The two pathogens were introduced separately as a four strains-cocktail and at high (>6.5 Log10 g-1) concentration into bedding materials, and their inactivation over a 10 weeks-period was monitored by using a Most Probable Number (MPN) enumeration method. Inactivation of E. coli O157:H7 was more effective in the bedding inoculated immediately after collection from calf pens than in the beddings inoculated after a 2 months-pre-storage period: E. coli O157:H7 levels were reduced by 6.6 Log10 g-1 in unstored bedding (0.5 Log10 g-1 recovered; 95%CI: 0.0-1.2), and by 4.9 Log10 g-1 in pre-stored bedding (2.2 Log10 g-1 recovered; 95%CI: 1.5-2.8) with a significant (p<0.05) difference between unstored and pre-stored. S. enterica was inactivated less effectively as counts were reduced by one order of magnitude, with no significant difference in inactivation between unstored and pre-stored beddings. Low levels of naturally occurring E. coli O157 and Salmonella spp. were detected in the non-inoculated beddings, as well as in the straw prior to use in the animal facility. To better understand the possible biological processes involved, the bacterial community present in the beddings was characterised by short-read 16S rRNA sequencing. Pre-storage of the bedding affected the composition but not the diversity of the bacterial community. Analyses of the key bacterial phyla suggested that the presence of a diverse and stable bacterial community might facilitate inactivation of the introduced pathogens, and a possible role of bacterial orders associated with lignocellulolytic resources. Overall, the study contributed to the understanding of the fate of zoonotic bacteria introduced in animal beddings during storage and identified bedding storage practices pre-and post-use in animal facilities that could be important to prevent the risk of zoonosis dissemination to the environment or to the dairy herds.

The Use of Hides during and after Calving in New Zealand Dairy Cows

Simple Summary

Dairy cows are known to seek isolation during calving. While some regions in the world provide individual calving pens, in pasture-based systems, cows frequently calve in large outdoor groups. We aimed to determine how provision of a “hide” would impact choice of calving location and behavior of the cow and calf. The hides in this study were designed with farmer-utility in mind and were built of heavy-duty gates that could fold out of the way when not needed. When opportunity for seclusion was available, approximately 20% of the cows calved within a hide; however, post-calving seclusion was frequently sought, with over half of the cow–calf pairs moving into hides. When cows and calves isolated after calving, their interaction with other animals was reduced. Hide presence resulted in more dispersed calving location compared to when hides were not available. Factors such as increasing stocking density, and cow age, reduced hide use. This work demonstrates that group housed cows should be provided with a choice regarding calving location.

Abstract

Isolation during calving is a common dairy cow behavior, however it has not been examined in large outdoor group settings. The provision of “hides” was monitored for its impact on calving location and cow–calf behavior. Stocking density and bedding management were either controlled (Phase 1) or managed according to farm practice (Phase 2). Hides were used for calving by 18% (Phase 1) and 22% (Phase 2) of the cows; a further 59% and 44% of cows moved into the hides after calving (Phase 1 and 2, respectively). When hides were not available, cows calved near the edges of the calving area. In Phase 2, as stocking density increased, cows tended to use the hides less. Older cows were less likely to isolate regardless of management. Cow–calf interaction with other cows and calves was lower when hides were available. There was no evidence that hides reduced incorrect matching of cows and calves by staff, however cases of “mismothering” (i.e., calves being taken by other dams) were observed. Since the majority of cows used the hides at some stage before or after calving, we suggest opportunities for seclusion should be provided in large calving groups.

Does orthodontic treatment affect caries levels?

Design A prospective cohort study.Exposure/sample selection In 2005/2006, the authors analysed data from participants in a previous oral epidemiological study conducted in 1988/1989. Children whom were clinically examined in the School Dental Clinics in South Australia in 1988/1989 were invited to a follow-up in 2005/2006. Respondents competed a questionnaire concerning their sociodemographic characteristics, dental health behaviours and the receipt of orthodontic treatment, and were invited for a clinical examination. Oral health information concerning decayed, missing and filled teeth (DMFT) and occlusal status using the Dental Aesthetic Index (DAI) were recorded by multiple trained calibrated dentists in accordance with the NIDR procedures. The study obtained ethical approval from the University of Adelaide and maintained informed consent at each stage of the study.Data analysis Data analysis was performed independently by the principle researcher. Analysis involved descriptive statistics, frequency distribution and cross tabulation. Explanatory variables for orthodontic treatment and dental outcomes were investigated for each DAI category using negative binominal regression using the online computer programme 'effect size calculator'. The statistical analysis was preformed using IBM SPSS statistics version 24. All explanatory variables were introduced into the adjusted negative binominal regression models based on their statistical significance from multiple linear regression models, with the p value set at 0.05.Results The response rate for the questionnaire was 34% (n = 632), with 74% (n = 473) of those attending for clinical examination. After exclusions, 24% (n = 448) of those originally contacted participated. Statistically significant differences in clinical outcomes were observed between those who had and had not visited the dentist in the last two years. These outcomes included missing teeth (MT), filled teeth (FT) and a higher DMFT score. In addition, brushing at least twice daily was associated with fewer decayed teeth (DT) and MT (p <0.001). Increased MT was observed among individuals who had orthodontic treatment across all DAI categories except for participants with very severe malocclusion. In this group, there were significantly more MT among the untreated participants (p <0.001). Thirty-five percent (n = 157) of participants reported a history of orthodontic treatment by the age of 30. No statistically significant associations were found between orthodontic treatment and all aspects of DMFT using adjusted models for participant self-reported sociodemographics, dental health behaviours and malocclusion.Conclusions Caries experience does not correlate with previous orthodontic treatment. Sociodemographic variables and dental health behaviours have a greater impact, and are associated with long-term disease outcomes, including numbers of DMFT. Caries experience is also associated with educational attainment and income level, frequency of tooth brushing and dental office attendance. In summary, orthodontic treatment does not provide superior long-term dental health outcomes in relation to caries. The hypothesis that those with previous orthodontic treatment would have lower caries experience was rejected.

10 year comparison of glass ionomer and composite resin restoration materials in class 1 and 2 cavities

Data sources A prospective randomised, double-blinded controlled trial Study selection Those requiring routine dental care in Sihhiye, Turkey were eligible to participate. Eighty-seven participants were identified and assessed for eligibility by calibrated researchers who ensured that the inclusion and exclusion criteria were met. Fifty-nine participants were successfully recruited with an average age of 24 years (range 15-37).Restoration type were randomly allocated [glass ionomer (GI) or composite resin (CR)] using a table of random numbers with software 'Research Randomised Program' and four experimental groups were created.Two dentists with 5 years experience were calibrated by them placing ten trial restorations , which were not included in the study. One hundred and forty restorations were then placed adhering to a strict treatment protocol. Cavities which did not meet the specifications of the criteria were excluded. The study received ethical approval by the Human Ethics in Clinical Research Committee of the University.Data extraction and synthesis Restorations were assessed at baseline (1 week), 1, 2, 3, 4, 5, 6, 8 and 10 years by blinded calibrated examiners with the aid of colour photographs using an objective criteria. Scanning electron microscopy (SEM) analysis was performed for one randomly selected restoration per group at each assessment. Data analysis adhered to the intention-to-treat CONSORT protocol. The restoration retention rates were calculated, and statistical analysis preformed using IBM SPSS version 22.0. The performance of the restorative materials over the study period were analysed with Cochran's Q test, according to USPHS criteria. Whilst the McNemar test was used to assess aspects of each material with baseline for each cavity type in addition to difference between cavity types. Marginal adaption, marginal discolouration and colour scores in each study group were compared with the p value set at 0.05.Results Eighty-seven patients with 203 lesions were included in the study, with 59 (140 lesions) eligible. Eleven patients were excluded for not meeting the inclusion/ exclusion criteria with 17 refusing to participate. Four randomly allocated groups were created at baseline, as combinations of cavity type and restorative material. 86.4% (n=51) of participants were evaluated after 10 years. The cumulative failure rate (CRF) was 3.17%.Marginal discolouration was observed in all groups at 10 years. With a significant difference observed between Class I and Class II cavities with GI restorations (p = 0.022). In addition, a significant change in colour match in GI restorations after 10 years(<0.005) was found.Over the ten-year period, no significant change was observed in terms of marginal adaption, anatomical form, secondary caries, postoperative sensitivity, surface texture, and retention for either restorative material (p >0.05) or with SEM inspections.Conclusions Both GI and CR are suitable and similar restorative materials for class 1 and class 2 cavities. However, differences can occur in colour change within the materials with glass ionomer restorations showing greater colour change from baseline over this period.

Cow Lying Behaviour and Bedding Quality Changes during Five Weeks on a Stand-Off Pad

Simple Summary

New Zealand dairy farmers place cows in uncovered off-paddock facilities for a part (e.g., 18 h) of the day to reduce their impact on pasture during winter. Lying time is a key indicator of whether these hybrid pasture systems are meeting welfare requirements. While it is easy to measure lying time in a research setting using accelerometers, it is not yet common to measure it on farm, and more convenient indicators are needed. We investigated the lying behaviour of dairy cows as bedding quality deteriorated over a five-week period to determine what measures may be useful as farmer-friendly indicators of cow welfare. The daily lying time of the two groups of cows on bedding according to normal farm practice (NFP) declined over the five weeks and was significantly less than that of cows on fresh bedding during the last 10 days of the trial. The fresh woodchip bedding contained less than 65% moisture throughout the trial. By week 3 and week 4, the moisture content of the lying surface exceeded 75% for NFP Group 2 and Group1, respectively. A bedding moisture threshold of 75% assessed by a ‘gumboot score’ and cows lying rather than grazing when on pasture may be useful farmer-friendly indicators of cow welfare because of their relationship with reduced lying time.

Abstract

Bedding quality and cow lying time were measured during five weeks in a normal farm practice (NFP) off-paddock system with no bedding refreshment. Two groups of 100 non-lactating dairy cows were compared to groups of 8 cows with fresh bedding (FB). The cows were on a woodchip pad for 18 h/d at a space allowance of 5.4 m²/cow, with 6 h/d on pasture for 5 weeks. Lying times were recorded continuously for 60 cows per group using accelerometers. Bedding moisture content was measured weekly. Data for each NFP group were analysed and compared with those of their respective FB group using repeated measures. The lying time declined over five weeks from 11.6 h/day during the first week to 5.6 h/day during the fifth week (SED = 0.3; F_1,25 = 351.56; p < 0.001). The moisture content of the bedding increased over the five weeks and was significantly higher for both NFP groups (NFP Group 1: F_5,59 = 8.33; p < 0.001; NFP Group 2: F_5,61 = 5.54; p < 0.001) than those of the respective FB groups. The percentage of total time lying when in the paddock increased for the NFP groups, reaching 15% in the last week of the trial. During five weeks on a stand-off pad, bedding quality deteriorated, and cows lay down less, to such an extent that welfare was compromised.

Detection of Invertebrate Suppressive Soils, and Identification of a Possible Biological Control Agent for Meloidogyne Nematodes Using High Resolution Rhizosphere Microbial Community Analysis

White clover (Trifolium repens) is the key legume component of New Zealand pastoral agriculture due to the high quality feed and nitrogen inputs it provides. Invertebrate pests constrain white clover growth and this study investigated rhizosphere-associated fungal controls for two of these pests and attempts to disentangle the underpinning mechanisms. The degree of suppressiveness of 10 soils, in a latitudinal gradient down New Zealand, to added Meloidogyne hapla and Costelytra zealandica scarab larvae was measured in untreated soil. Most of the soils showed no suppressive activity against these pests but two showed activity against M. hapla and two against C. zealandica. Rhizosphere fungi responsible for pest suppressive responses were elucidated via next-generation sequencing. In the M. hapla-suppressive soils nematode-trapping Orbiliomycetes fungi were present in significantly greater abundance than non-suppressive soils and their abundance increased further with addition of M. hapla. A comparison of plant growth and the rhizosphere fungal community between untreated and irradiated soil was carried out on 5 of the 10 soils using Pyronota as the scarab larvae. Soil irradiation either: reduced (by 60-70%); increased (16×) or made no difference to white clover growth across the five soils tested, illustrating the range of microbial impacts on plant production. In one of the M. hapla suppressive soils irradiation resulted in a significant increase in nematode galling suggesting that Orbiliomycetes fungi were indeed responsible for the suppressive effect. Lack of consistent changes in soil macronutrients and pH post-irradiation suggest these were not responsible for plant or invertebrate responses. The use of next generation sequencing in controlled pot trials has allowed identification of a potential biological control organism and bioindicator for M. hapla suppression.

Assessing DNA methylation levels in animals: choosing the right tool for the job

Selection of agricultural animals for improved performance based on genetics has seen significant progress made over the past few decades. Further improvements are likely by combining genetic selection with epigenetic selection or manipulation. However, before this can be undertaken, an understanding of epigenetic mechanisms is required, and this can be obtained only by precise and accurate analysis of epigenetic patterns. Even when one only considers a single epigenetic modification such as DNA methylation, the last 10 years have seen a wide array of technologies developed. For scientists whose primary training is in a field other than epigenetics, the choices can be confusing, and it can be challenging to determine which technology is best for the task at hand. There are many factors to take into consideration before beginning analysis of DNA methylation in animals. It is crucial that the most appropriate tools are selected to ensure that the best possible results are achieved. This review provides an overview of the most common methods of analysing DNA methylation in animals, when they are appropriate, what resolution of information they can provide and what their limitations are.

Prevalence, concentration and genotypes of Campylobacter jejuni in faeces from dairy herds managed in farm systems with or without housing

AIM

To determine the faecal excretion of Campylobacter jejuni by dairy cows that used housing in combination with outdoor grazing.

METHODS AND RESULTS

Campylobacter jejuni prevalence and concentration were measured in a total of 990 cow faecal samples collected from seven herd home farms (HH), seven stand-off pad farms (SOP) and seven pasture farms (P) over a 2-year period. On all the farms, cows had access to pasture but were restricted to narrow grazing strips in winter. The overall Camp. jejuni prevalence was 55, 49 and 54% on HH, SOP and P farms, respectively. The Camp. jejuni concentration ranged from 0 to 6·7 log10 g(-1) faeces and was not statistically different among the farm systems. However, Camp. jejuni prevalence (P = 0·014) and concentration (P = 0·0001) were significantly greater in winter and early spring after intensive use of HH, SOP and strip-grazing. Typing of 30 Camp. jejuni isolates revealed a dominance of ruminant types (MLST CC-61, CC-21, CC-42 and CC-48), which are associated with human disease.

CONCLUSION

No overall difference was observed among systems, but seasonal management practices that force cows close together increased the prevalence and concentration of Camp. jejuni in faeces.

SIGNIFICANCE AND IMPACT OF THE STUDY

These findings are important when identifying farm practices that reduce Camp. jejuni excretion and the associated risk to human health.

Comparison of left ventricular performance in healthy young women and men during exercise

BACKGROUND

Previous studies show sex-related differences in left ventricular (LV) response to exercise. It is not clear, however, whether these differences are also seen in younger healthy subjects.

METHODS AND RESULTS

This study examined the changes in LV performance during dynamic upright exercise in 11 healthy men and 19 healthy young women according to the Bruce protocol and an individualized ramp protocol. There were no significant differences between the two protocols for either men or women in heart rate, blood pressure, LV ejection fraction (EF) (measured by ambulatory nuclear detector), and measured oxygen consumption. The peak oxygen consumption was higher in men than in women (44 +/- 13 vs 36 +/- 9 ml/kg/min; p < 0.05), but the peak heart rate, systolic blood pressure, and EF were similar. The change in EF (from rest to exercise) was 19% +/- 8% in men and 19% +/- 11% in women with the Bruce protocol (difference not significant) and 26% +/- 9% in men and 19% +/- 6% in women with the ramp protocol (difference not significant). At peak exercise, both men and women showed an increase in end-diastolic volume (29% +/- 14% vs 23% +/- 11%; difference not significant) and a decrease in end-systolic volume (41% +/- 15% vs 43% +/- 21%) (difference not significant). The increase in cardiac output during exercise was due to an increase in heart rate and stroke volume in both men and women. At submaximal exercise, however, the decrease in end-systolic volume was less in women than in men (p < 0.05).

CONCLUSIONS

There are no sex-related differences in compensatory mechanism during dynamic exercise in healthy subjects. The changes in contractility and LV volume are not affected by the exercise protocol.

Results of adenosine single photon emission computed tomography thallium-201 imaging in hemodynamic nonresponders

Systolic blood pressure typically decreases during adenosine infusion because of stimulation of A2b receptors, resulting in systemic vasodilation. This study examined the results of adenosine single photon emission computed tomography (SPECT) thallium-201 imaging in patients who did not show such a decrease in blood pressure during peak adenosine effect (nonresponders). The 102 nonresponders and 341 responders had no significant differences in age, gender, history of diabetes mellitus, hypertension, or previous myocardial infarction. The extent of coronary artery disease (CAD) by angiography was also similar. The sensitivity of SPECT thallium-201 imaging in patients with one-vessel disease was 82% in nonresponders and 84% in responders (p value not significant [NS]); in patients with multivessel disease, it was 90% in nonresponders and 94% in responders (p = NS) and for all CAD, it was 87% in non-responders and 91% in responders (p = NS). Thus lack of hemodynamic systemic response during adenosine infusion does not affect sensitivity for detecting CAD.

Assessment of myocardial viability by dynamic tomographic iodine 123 iodophenylpentadecanoic acid imaging: comparison with rest-redistribution thallium 201 imaging

BACKGROUND

This study examined the ability of dynamic 123I-labeled iodophenylpentadecanoic acid (IPPA) imaging to detect myocardial viability in patients with left ventricular (LV) dysfunction caused by coronary artery disease.

METHODS AND RESULTS

Serial 180-degree single-photon emission computed tomographic (SPECT) images (five sets, 8 minutes each) were obtained starting 4 minutes after injection of 2 to 6 mCi 123I at rest in 21 patients with LV dysfunction (ejection fraction [EF] 34% +/- 11%). The segmental uptake was compared with that of rest-redistribution 201Tl images (20 segments/study). The number of perfusion defects (reversible and fixed) was similar by IPPA and thallium (11 +/- 5 vs 10 +/- 5 segments/patient; difference not significant). There was agreement between IPPA and thallium for presence or absence (kappa = 0.78 +/- 0.03) and nature (reversible, mild fixed, or severe fixed) of perfusion defects (kappa = 0.54 +/- 0.04). However, there were more reversible IPPA defects than reversible thallium defects (7 +/- 4 vs 3 +/- 4 segments/patient; p = 0.001). In 14 patients the EF (by gated pool imaging) improved after coronary revascularization from 33% +/- 11% to 39% +/- 12% (p = 0.002). The number of reversible IPPA defects was greater in the seven patients who had improvement in EF than in the patients without such improvement (10 +/- 4 vs 5 +/- 4 segments/patient; p = 0.075).

CONCLUSIONS

123I-labeled IPPA SPECT imaging is a promising new technique for assessment of viability. Reversible defects predict recovery of LV dysfunction after coronary revascularization.

Serial changes in left ventricular function after coronary artery bypass: implications in viability assessment

Improvement in left ventricular (LV) performance after coronary artery bypass surgery remains the gold standard in myocardial viability assessment. The time-related changes, however, are not well known. This study examined the LV ejection fraction (EF) by gated blood pool imaging early (6 +/- 4 days) and late (62 +/- 24 days) after surgery in patients with normal preoperative EF (group 1, n = 12) and those with LV dysfunction (group 2, n = 15). There were no changes in the clinical status between the early and late studies, and all patients had normal sinus rhythm. Group 1 had no significant change in EF (preoperatively 62%, early postoperatively 64%, late postoperatively 63%; p = NS). In group 2, EF was 26% +/- 8% preoperatively; 30% +/- 10% early postoperatively; and 34% +/- 8% late postoperatively (p < 0.05). Postoperatively there was > or = 5% improvement in EF in 4 patients early and 11 patients late (p < 0.05). Patients who showed early improvement continued to do so in the late study but, additionally, 7 patients showed improvement only in the late study. Thus the timing of EF measurement after surgery is important in patients with LV dysfunction but not in patients with normal LV function. Early assessment may underestimate the prevalence and degree of recovery.

Prognostic significance of silent ischemia

This study examined the prognostic predictors in 521 patients with angiographic evidence of coronary artery disease (CAD). All patients underwent exercise single-photon emission computed tomographic thallium imaging. The patients were divided into those with symptomatic ischemia defined as reversible thallium defects, S-T segment depression (or both) and angina during exercise (n = 210, group 1), and silent ischemia defined as thallium defects or ST segment depression (or both) but no angina during exercise (n = 311, group 2). During a mean follow-up of 24 +/- 21 months, there were 30 cardiac events (death or nonfatal myocardial infarction). The extent of CAD (2.0 +/- 0.8 diseased vessels in group 1 and 2.1 +/- 0.8 diseased vessels in group 2), the left ventricular ejection fraction, the extent of perfusion abnormality (21% +/- 11% in group 1 and 24% +/- 12% in group 2), and the peak heart rate and double product were similar in the two groups. Survival analysis showed no significant difference in the event-free survival in patients with symptomatic or silent ischemia. The 2-year event-free survival rate was 95% in group 1 and 94% in group 2 (difference not significant). The extent of perfusion abnormality and history of diabetes mellitus were the most important predictors of events. Thus the prognosis of medically treated patients with CAD is comparable in those patients with silent or symptomatic ischemia and is dependent on the extent of myocardium at risk rather than presence or absence of angina pectoris during exercise.

Planar and tomographic imaging with technetium 99m-labeled tetrofosmin: correlation with thallium 201 and coronary angiography

This study compared the results of planar and single-photon emission computed tomographic (SPECT) imaging with tetrofosmin with those of 201Tl and coronary angiography. In three normal volunteers the images were normal by both 201Tl and tetrofosmin (planar and SPECT). In 23 patients with coronary artery disease, the images were abnormal in 20 patients by SPECT tetrofosmin, in 19 by planar tetrofosmin, in 20 by SPECT thallium, and in 18 by planar thallium (difference not significant). Both planar and SPECT images were divided into five segments per patient. There were 58 perfusion defects by SPECT tetrofosmin, 50 by planar tetrofosmin (difference not significant), 47 by SPECT thallium, and 42 by planar thallium (difference not significant). Perfusion defects were reversible in 47 segments (36%) by SPECT tetrofosmin, 35 (27%) by planar tetrofosmin, 31 (24%) by SPECT thallium (p < 0.05 vs SPECT tetrofosmin), and 31 (24%) by planar thallium (difference not significant). Among the 23 patients with coronary artery disease, 19 underwent coronary angiography. In these patients there were 32 diseased coronary arteries. Perfusion defects were present in 21 territories (66%) by SPECT tetrofosmin, 19 (59%) by planar tetrofosmin, 20 (63%) by SPECT thallium, and 18 (56%) by planar thallium. There was agreement between thallium and tetrofosmin in 108 of 130 segments (kappa statistics = 0.69 +/- 0.06). The images, especially with SPECT, are better with tetrofosmin than with 201Tl. Thus myocardial imaging with tetrofosmin provides results that are at least as good as those of 201Tl. Slightly more abnormal segments and more reversible defects are detected by tetrofosmin than by thallium imaging, especially with SPECT imaging.

Prognostic value of adenosine single-photon emission computed tomographic thallium imaging in medically treated patients with angiographic evidence of coronary artery disease

BACKGROUND

This study examined the prognostic value of adenosine single-photon emission computed tomographic thallium imaging in medically treated patients with angiographic evidence of coronary artery disease (CAD).

METHODS AND RESULTS

Patients who underwent coronary revascularization within 3 months of this study were excluded. There were 177 patients aged 64 +/- 11 years; 74 had one-vessel, 57 had two-vessel, and 46 had three-vessel CAD (> or = 50% diameter stenosis). During a mean follow-up of 22 +/- 13 months, there were 14 events (cardiac death or nonfatal myocardial infarction). Cox survival analysis with important clinical, catheterization, and scintigraphic variables identified the size of perfusion abnormality as the strongest predictor of events (chi 2 = 9). Life-table analysis showed that patients with perfusion defects of 15% or greater of the myocardium had a worse prognosis than had patients with no or smaller defects (Mantel-Cox statistic = 13; p < 0.001).

CONCLUSIONS

Thus adenosine single-photo emission computed tomographic thallium imaging provides important prognostic data in medically treated patients with CAD. The extent of thallium abnormality is the most important predictor of events.

Comparison of the treadmill exercise score and single-photon emission computed tomographic thallium imaging in risk assessment

BACKGROUND

This study compared the prognostic value of exercise single-photon emission computed tomographic (SPECT) thallium imaging with that of treadmill exercise score in medically treated patients with coronary artery disease (CAD).

METHODS AND RESULTS

The treadmill exercise score was derived from exercise duration, degree of ST segment depression, and the treadmill anginal index. There were 121 patients with no CAD and 316 patients with angiographically defined CAD (> or = 50% diameter stenosis of one or more vessels). During a mean follow-up of 29 months, there were 35 cardiac deaths or nonfatal myocardial infarctions. Multivariate Cox survival analysis showed the extent of thallium imaging abnormality and CAD to be independent predictors of prognosis. On the other hand, the treadmill exercise score was not a significant predictor even on univariate analysis. The results of thallium uptake were the strongest independent predictors of prognosis and in addition provided incremental prognostic power to coronary angiography (chi 2 = 29 for SPECT, 27 for coronary angiography, and 37 for both).

CONCLUSIONS

Thus exercise SPECT thallium imaging is significantly better than the treadmill exercise score in risk assessment. The size of the perfusion abnormality is an important predicator of prognosis.

Age- and sex-related differences in the use of coronary angiography in patients undergoing adenosine SPECT thallium imaging

BACKGROUND

Recent reports suggest sex-related differences in the management of patients with coronary artery disease.

METHODS

This study examined the pattern of use of coronary angiography in 535 patients initially referred for adenosine single photon emission computed tomography (SPECT) thallium imaging.

RESULTS

Coronary angiography was carried out more often in patients under 70 years of age than those over 70 years of age [107 out of 322 (33%) versus 50 out of 213 (23%), P < 0.01]. Even in patients with abnormal adenosine SPECT thallium results, coronary angiography was less frequently performed in the elderly [40 out of 130 (31%) versus 82 out of 178 (46%), P < 0.01]. Women underwent coronary angiography less often than men [56 out of 261 (21%) versus 101 out of 274 (37%), P < 0.0002]. This difference was due to differences in patients under 70 years of age [31 out of 138 women (22%) versus 76 of 184 men (41%), P < 0.003)], but not in patients over 70 years of age. In patients with abnormal adenosine thallium image results, the difference between men and women was still present: 37 out of 112 women (33%) versus 85 of 196 men (43%) underwent coronary angiography (P = 0.05). Stepwise discriminant analysis of clinical and scintigraphic variables identified four independent predictors of the need for coronary angiography; the abnormal thallium image results (chi 2 = 33, P < 0.0001); the size of the perfusion abnormality (chi 2 = 7, P < 0.01); sex (chi 2 = 7, P < 0.01) and age (chi 2 = 4, P < 0.05).

CONCLUSION

Coronary angiography is less often performed in women and elderly patients even when initial screening results are abnormal. The relation of this observation to subsequent clinical course and events requires further studies.

Simultaneous assessment of left ventricular perfusion and function with technetium-99m sestamibi after coronary artery bypass grafting

This study examined the left ventricular perfusion and EF by using simultaneous SPECT and first-pass radionuclide angiography with technetium 99m sestamibi in 95 patients after uncomplicated coronary artery bypass grafting. The patients were divided into those with normal EF and no previous myocardial infarction before surgery (group 1, n = 57), and those with abnormal EF or infarction (group 2, n = 38). The SPECT images were normal in 37 patients in group 1 and in 6 patients in group 2 (p < 0.0001). The patients with normal SPECT images had a higher EF after surgery than those with abnormal images (65% +/- 10% vs 50% +/- 14%, p < 0.0001) and was higher in group 1 than in group 2 (64% +/- 8% vs 46% +/- 16%, p < 0.0001). There was a significant correlation between the EF and the extent of perfusion abnormality (r = -0.44, p < 0.0001). The patients with normal SPECT images could not be separated from those with abnormal images based on peak CK, CK-MB, and the electrocardiographic changes. Of the 69 patients with postoperative EF > or = 50%, the perfusion pattern was normal in 41 and abnormal in 28; of the 26 patients with EF < 50%, 24 had abnormal SPECT (p < 0.003). There was no significant change in mean EF after surgery (55% +/- 14% before vs 56% +/- 15% after). Thus simultaneous assessment of left ventricular perfusion and function after coronary artery bypass grafting showed that an abnormal perfusion pattern may exist despite a normal EF. These patients could not be predicted by enzymes or electrocardiographic changes.

Study of myocardial infarct remodeling by single-photon emission computed tomographic imaging

Left ventricular (LV) remodeling after Q-wave anterior acute myocardial infarction (AMI) was examined with single-photon emission computed tomographic thallium imaging. Initial (after adenosine infusion) and 4-hour delayed reinjection images were obtained in 34 patients aged 65 +/- 12 years. Short-axis slices from the delayed images were quantitatively analyzed by measuring the outer and inner diameters, and wall thickness. The results were compared with those in a group of normal subjects. The outer diameter was greater in patients than in normal subjects at the apical, mid- and basal levels (all p < 0.01); the average outer diameter was 16.9 +/- 1.9 mm in patients, and 12.2 +/- 1.3 mm in normal subjects (p < 0.001). Similarly, the inner diameter was greater in patients than in normal subjects at the 3 levels (all p < 0.05); the average inner diameter was 6.5 +/- 1.8 mm in patients, and 4.7 +/- 1.3 mm in normal subjects (p < 0.01). Wall thickness was greater in patients than in normal subjects (5.2 +/- 0.5 vs 3.8 +/- 0.5 mm; p < 0.0001). There were significant correlations between LV dilation and time elapsed (in weeks) since AMI (r = 0.57; p < 0.005), and the size of the perfusion abnormality (r = 0.44; p < 0.03). Thus, LV dilation occurs after Q-wave anterior AMI, and is related to infarct size and duration. These changes can be studied by single-photon emission computed tomographic thallium imaging.

Independent and incremental prognostic value of exercise single-photon emission computed tomographic (SPECT) thallium imaging in coronary artery disease

OBJECTIVES

The objective of this study was to examine the independent and incremental prognostic value of exercise single-photon emission computed tomographic (SPECT) thallium imaging in patients with angiographically defined coronary artery disease.

BACKGROUND

Previous studies showed the importance of exercise thallium-201 in risk stratification. However, most of these studies used planar imaging techniques.

METHODS

Follow-up data were obtained in 316 medically treated patients with coronary artery disease. Cox proportional hazards regression models were used to examine the independent and incremental prognostic values of clinical, exercise, thallium and cardiac catheterization data.

RESULTS

There were 35 events (cardiac death or nonfatal myocardial infarction) at a mean follow-up time of 28 months. Univariate analysis showed that gender (chi-square = 5.1), exercise work load (chi-square = 3.1), extent of coronary artery disease and left ventricular ejection fraction (chi-square = 14.8) and thallium variables (chi-square = 22.7) were prognostically important. The thallium data provided incremental prognostic value to catheterization data (chi-square = 33.7, p < 0.01). The extent of the perfusion abnormality was the single best predictor of prognosis (chi-square = 14). Patients with a large perfusion abnormality had a worse prognosis than that of patients with a mild or no abnormality (Mantel-Cox statistics = 10.6, p < 0.001).

CONCLUSIONS

In medically treated patients with coronary artery disease, exercise SPECT thallium imaging provides independent and incremental prognostic information even when catheterization data are available. The extent of the perfusion abnormality is the single most important prognostic predictor.

Identification of extensive coronary artery disease in women by exercise single-photon emission computed tomographic (SPECT) thallium imaging

OBJECTIVES

The aim of this study was to examine the ability of exercise single-photon emission computed tomographic (SPECT) thallium imaging to identify high risk women with left main or three-vessel coronary artery disease using a stepwise discriminant analysis.

BACKGROUND

Previous studies have used statistical methods to identify high risk men with coronary artery disease. Only limited data are available in women.

METHODS

Exercise SPECT thallium imaging and coronary arteriography were performed for evaluation of chest pain in 243 women. Group 1 comprised 58 women with left main or three-vessel coronary disease and group 2 comprised 185 women with no or one- or two-vessel disease. Stepwise discriminant analysis was used to determine predictors of left main or three-vessel disease.

RESULTS

On univariate analysis, women in group 1 were older (p < 0.03) and had a lower exercise work load (p < 0.02), lower exercise heart rate (p < 0.004), higher prevalence rate of diabetes mellitus (p < 0.0003) and more multivessel thallium abnormality (p < 0.0001) compared with women in group 2. On multivariate analysis, only multivessel thallium abnormality (F = 43) and exercise heart rate (F = 6) were independent predictors of left main or three-vessel coronary disease. A model based on these two variables separated the women into three risk groups: 99 patients with 9%, 70 patients with 23% and 74 patients with 45% prevalence of left main or three-vessel disease (p < 0.0001).

CONCLUSIONS

High risk women with left main or three-vessel coronary disease can be identified by exercise SPECT thallium imaging.

Identification of high-risk patients with left main and three-vessel coronary artery disease by adenosine-single photon emission computed tomographic thallium imaging

The purpose of this study was to examine the ability of SPECT imaging with thallium-201 during adenosine-induced coronary hyperemia to detect high-risk patients with left main or three-vessel CAD. There were 339 patients: 102 with either left main or three-vessel CAD (group 1) and 237 with no CAD, one-, or two-vessel disease (group 2). By means of univariate analysis, several variables were found to differ between groups 1 and 2: Q wave myocardial infarction (35% vs 25%, p < 0.05), ST segment depression (35% vs 19%, p < 0.001), age (67 +/- 9 vs 62 +/- 10 years, p < 0.001), resting systolic blood pressure (142 +/- 22 vs 135 +/- 20 mm Hg, p < 0.01), abnormal thallium images (95% vs 74%, p < 0.0001), multivessel thallium abnormality (76% vs 39%, p < 0.0001), extent of thallium abnormality (24 +/- 11% vs 19 +/- 13%, p < 0.0001), and increased lung thallium uptake (39% vs 15%, p < 0.01). According to stepwise discriminant analysis, only three variables were predictors of high risk: multivessel thallium abnormality (chi 2 = 27), increased lung thallium uptake (chi 2 = 10), and ST depression (chi 2 = 5). On the basis of these variables, patients were divided into three groups with different prevalence rates for left main and three-vessel CAD: 63% in 68 patients, 30% in 137 patients, and 13% in 137 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

The treadmill exercise score revisited: coronary arteriographic and thallium perfusion correlates

The treadmill exercise score has been used to stratify patients into low-, moderate-, and high-risk groups. This score is derived from ST segment depression, angina, and exercise duration. To determine the coronary arteriographic and exercise thallium perfusion correlates of the score, we examined the extent of coronary artery disease and exercise single photon emission computed thallium-201 results in 834 patients for whom cardiac catheterization data were available. Of those, 174 had no coronary artery disease, 195 had one-vessel, 246 had two-vessel, and 219 had three-vessel disease. Based on the treadmill exercise score, 369 were in the low-risk, 384 in the moderate-risk, and 81 in the high-risk group. The extent of coronary artery disease was 2.1 +/- 1 diseased vessels in the high-risk, 1.7 +/- 1 in the moderate, and 1.4 +/- 1.1 in the low-risk group (p < 0.01). The extent of the thallium abnormality (maximum number of abnormal segments 120/patient) was 10 +/- 6 in the high-risk, 7 +/- 6 in the moderate, and 6 +/- 5 in the low-risk group (p < 0.05). Based on the extent of coronary artery disease and results of thallium imaging, patients were reclassified into three groups: group 1 had three-vessel disease and/or > or = 10 abnormal segments (n = 387), group 3 had no coronary artery disease or one-vessel disease and less than five abnormal segments (n = 212), and the remaining patients were in group 2 (n = 235).(ABSTRACT TRUNCATED AT 250 WORDS)

The perfusion pattern in coronary artery occlusion: comparison of exercise and adenosine.p6

This study compared exercise to adenosine thallium-201 single photon emission computed tomography in detecting occlusion of left anterior descending or right coronary arteries in patients with no previous myocardial infarction. There were 41 patients who underwent adenosine thallium imaging (adenosine infusion at a rate of 140 micrograms/kg/min for 6 min), and 143 patients who underwent exercise thallium imaging. There were more patients with right coronary than left anterior descending coronary artery occlusion. Thus, in the adenosine group, there were 15 patients with left anterior descending artery occlusion, and 26 with right coronary artery occlusion, and in the exercise group, there were 46 patients with left anterior descending artery occlusion, and 97 patients with right coronary artery occlusion. In the adenosine group, the thallium images were abnormal in 41 patients (100%), while in the exercise group, the thallium images were abnormal in 125 patients (87%, P < 0.02) in the territories of the occluded arteries. ST segment depression was noted in 19 patients (46%) in the adenosine group, and 69 patients (48%) in the exercise group (P:NS). In patients with isolated single vessel occlusion, the size of the perfusion abnormality was 28 +/- 9% with adenosine, and 21 +/- 12% with exercise (P:NS). Thus, most patients with occlusion of the left anterior descending or right coronary artery have regional perfusion abnormality during stress; the different role of collaterals with each type of stress may explain the higher percentage of abnormal results with adenosine than exercise.

Single photon emission computed tomographic teboroxime imaging with a preprocessing masking technique

We previously reported that single-head SPECT imaging with teboroxime is feasible. However, excessive hepatic uptake in some patients may interfere with image interpretation. This study examined the feasibility of improving image quality by use of a preprocessing masking technique to subtract hepatic activity. A band of 10 pixels in width adjacent to the inferior cardiac silhouette was marked on the raw planar images, and then SPECT reconstruction was done with the Butterworth filter with a frequency cutoff of 0.3 cycles/cm and the power of 10. The stress and rest images were compared before and after masking in 10 patients who underwent SPECT teboroxime imaging during adenosine-induced coronary hyperemia (140 micrograms/kg/min for 6 minutes). SPECT imaging with a single-head detector was performed with the use of a 180-degree anterior arc (from the 45-degree left posterior oblique projection to the 45-degree right anterior oblique projection); 32 images at 8 seconds per stop were obtained (total imaging time = 6.8 minutes). All images were considered subjectively better after the masking technique was used, especially for assessment of inferior wall perfusion pattern. The maximum count in any pixel was in the hepatic region of interest before masking and in the cardiac region of interest after masking (303 +/- 110 counts vs 166 +/- 55 counts; p < 0.001). The difference was especially pronounced in the images that were obtained when patients were at rest (366 +/- 102 counts vs 184 +/- 64 counts; p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Early thallium imaging after percutaneous transluminal coronary angioplasty: tomographic evaluation during adenosine-induced coronary hyperemia

This study examined the immediate results of 201Tl imaging during adenosine-induced coronary hyperemia in 25 patients with one-vessel coronary artery disease, 4 +/- 3 days after percutaneous transluminal coronary angioplasty (PTCA). There were special features in our study: use of quantitative angiography and single-photon emission computed tomography (SPECT); a homogeneous group of patients (one-vessel disease) and a uniform stress (adenosine infusion). As a group, quantitative coronary angiography showed a decrease in percent diameter stenosis from 72% +/- 12% to 23% +/- 14%, p < 0.001. The thallium images were normal in 17 patients and abnormal in eight patients. However, of the eight patients, four had residual stenosis either in a secondary branch or downstream; one patient had local dissection (the residual stenosis could not be assessed reliably), two patients had > 50% residual diameter stenosis, and one patient had previous Q-wave myocardial infarction with a corresponding fixed thallium defect. In each of the eight patients with an abnormal image, a logical explanation could be identified. Thus, our results suggest that maximum reactive coronary hyperemia returns to normal immediately after PTCA, and that abnormal thallium results are due to inadequate dilatation or associated lesions.

Side effects during adenosine thallium imaging with single-port or double-port infusion protocols

The double-port infusion protocol during adenosine thallium imaging involves the use of two infusion systems, one for adenosine and one for thallium. The single-port infusion protocol, on the other hand, uses one infusion system; both adenosine and thallium are injected via a "Y" connection. This study examined the possibility that the single infusion system, by displacing a column of blood filled with adenosine, may be responsible for a greater incidence of side effects. In a parallel study, 140 patients underwent adenosine thallium imaging with the single-port system (group 1) and 140 patients underwent imaging with the double-port system (group 2). Both groups were comparable in age (67 +/- 10 years vs 64 +/- 11 years), gender (men comprised 56% of patients in group 1 and 64% in group 2), resting heart rate, and systolic blood pressure. More patients in group 1 had chest pains (57% vs 44%; p = 0.03), ST-segment depression (25% vs 9%; p = 0.005), nausea (11% vs 4%; p = 0.04), and second- or third-degree atrioventricular block (11% vs 5%; p less than 0.08) than did patients in group 2. The other side effects were similar, and peak heart rate and peak systolic blood pressure were also similar. The thallium images that used single-photon emission computed tomography were abnormal in 61% of patients in group 1 and in 65% of patients in group 2 (p = not significant).(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanism of exercise-induced hypotension in coronary artery disease

Hypotension during exercise testing has been considered a marker of extensive coronary artery disease (CAD) and poor prognosis. The mechanism of hypotension was examined in 25 CAD patients who developed hypotension during treadmill exercise testing (mean decrease in systolic blood pressure [BP] 33 +/- 13 mm Hg) (group 1) and was compared with the results of 25 CAD patients who had a normal systolic BP response to exercise (mean increase 53 +/- 15 mm Hg) (group 2). The 2 groups were comparable in age, sex, extent of CAD, previous myocardial infarction, left ventricular ejection fraction, history of hypertension and cardiac medications. Exercise heart rate (121 +/- 23 vs 133 +/- 25 beats/min; p = not significant [NS]) and duration (6 +/- 2 vs 7 +/- 3 minutes; p = NS) were comparable. ST-segment depression occurred in 44% of patients in group 1 and in 52% in group 2 (p = NS), and angina during exercise occurred in 60% of both groups. Single-photon emission computed tomographic thallium images were abnormal in 24 patients (96%) in group 1 and in 20 patients (80%) in group 2 (p = NS). Percent thallium abnormality was 19 +/- 12% in group 1, and 18 +/- 14% in group 2 (p = NS), and the severity of thallium abnormality was 710 +/- 510 in group 1, and 510 +/- 500 in group 2 (p = NS). Ischemia involving the inferior/posterior segments was seen in 68% of patients in group 1 and in 60% in group 2 (p = NS). Increased lung thallium uptake was seen in 48% of both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrioventricular block during adenosine thallium imaging

Transient atrioventricular (AV) block has been reported during adenosine thallium imaging. This study examined the predictors and hemodynamic implications in 55 patients who had second- or third-degree AV block (group 1) and compared the results with those in 803 patients who did not have AV block (group 2). There were no significant differences in age, sex, or heart rate at baseline between the two groups. ST segment depression was observed in 25% of patients in group 1 and 16% in group 2 (p = NS). Chest pain occurred in 56% in group 1 and 44% in group 2 (p = NS). Preexisting conduction abnormalities (17% vs 16%) and treatment with digitalis (15% vs 15%) and beta-blockers (31% vs 36%) were similar in the two groups. The results of thallium imaging were abnormal in 66% in group 1 and 67% in group 2 (p = NS). Reversible thallium defects were seen in 51% in group 1 and 52% in group 2 (p = NS). The AV block appeared during the first 2 minutes of infusion in 40 patients (73%) and disappeared despite continuation of infusion in 43 (78%). The heart rate during AV block was 79 +/- 18 beats/min, and the systolic blood pressure was 127 +/- 27 mm Hg. Premature termination of adenosine infusion was required in one patient (2%). Aminophylline was used in 5% in group 1 and 2% in group 2 (p = NS). Thus AV block is transient, occurs during the early minutes of infusion, is not aggravated by digitalis or beta-blocker therapy, can be seen in patients with normal perfusion images, and is often well tolerated.

Comparison of same-day protocols using technetium-99m-sestamibi myocardial imaging

Two same-day protocols (rest/exercise [Protocol 1] and exercise/rest [Protocol 2]) with sestamibi (hexakis 2-methoxy-2-isobutyl-isonitrile) were performed within 2 to 14 days of each other after randomization. The initial study in each protocol was done using a dose of 185-296 MBq of 99mTc-sestamibi. The second study in each protocol used a dose of 555-925 MBq. SPECT imaging was started 30 to 60 min after injection using a 180 degrees anterior arc. Segmental analysis was interpreted as normal, scar or ischemia (20 segments/patient). Among the protocols, there was concordance in 93% of the segments (593/640 segments). In the 11 patients with coronary artery disease and no prior myocardial infarction who had ischemic abnormality, count densities from abnormal and normal zones were compared between the two protocols. Protocol 1 showed greater count differences between abnormal and normal zones on exercise images with better normalization of abnormality on rest images than Protocol 2 (p less than 0.05). Technetium-99m-sestamibi provides high quality images using either of the two same-day protocols. However, the rest/exercise protocol provides better image contrast and ability to detect reversibility of perfusion defects, and is the preferred same-day protocol.

Tomographic myocardial perfusion imaging with technetium-99m teboroxime during adenosine-induced coronary hyperemia: correlation with thallium-201 imaging

Single-photon emission computed tomographic imaging with technetium-99m teboroxime during exercise has been found to be feasible and the results correlate with those obtained with thallium-201. This study examined the feasibility of this technique and compared tomographic imaging with technetium-99m teboroxime during adenosine-induced coronary hyperemia with thallium-201 imaging. With the patient positioned on the imaging table, adenosine was infused at a rate of 140 micrograms/kg per min for 6 min. At 4 min, 20 to 25 mCi (740 to 925 MBq) of technetium-99m teboroxime was injected intravenously and imaging was started as soon as the infusion was completed with use of a 180 degrees anterior arc and 32 stops at 10 s/stop (total imaging time 7.8 min). Rest images were obtained 60 to 90 min later with use of a similar dose of technetium-99m teboroxime. Exercise tomographic thallium images were obtained within 2 weeks of the teboroxime studies. In the 20 patients studied, the teboroxime images were normal in 2 (50%) of 4 normal subjects and abnormal in 15 (94%) of 16 patients with coronary artery disease; 4 of the 15 had a fixed defect and 11 a reversible defect. There was agreement between teboroxime and thallium studies in 16 patients (80%), in 319 (80%) of 400 segments and in 50 (83%) of 60 vascular segments (p less than 0.05). In two normal subjects, an apparent fixed defect involving the inferior wall was seen on the teboroxime but not the thallium images and was thought to be due to an attenuation artifact secondary to extracardiac activity in the left lobe of the liver.(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of coronary artery disease using single-photon emission computed tomography with thallium-201 during adenosine-induced coronary hyperemia

Thallium-201 myocardial imaging during dipyridamole-induced coronary hyperemia has been an accepted method for diagnosing coronary artery disease (CAD) and risk stratification. Adenosine is a powerful short-acting coronary vasodilator. Initial results of thallium imaging during adenosine infusion have been encouraging. In 132 patients with CAD and in 16 patients with normal coronary angiograms, adenosine was given intravenously at a dose of 0.14 mg/kg/min for 6 minutes and thallium-201 was injected at 3 minutes. The thallium images using single-photon emission computed tomography were abnormal in 47 of the 54 patients (87%) with 1-vessel, in 34 of 37 patients (92%) with 2-vessel and in 40 of 41 patients (98%) with 3-vessel CAD. The sensitivity was 92% in the 132 patients with CAD (95% confidence intervals, 86 to 96%). In patients with normal coronary angiograms, 14 of 16 patients had normal thallium images (specificity, 88%; 95% confidence intervals, 59 to 100%). The results were very similar when subgroups of patients were analyzed: those without prior myocardial infarction, elderly patients and women. The nature of the perfusion defects (fixed or reversible) was assessed in relation to whether the 4-hour delayed images were obtained with or without the reinjection technique. In patients who underwent conventional delayed imaging, there were more fixed perfusion defects than in patients with reinjection delayed imaging (16 vs 0%, p less than 0.0001). The adverse effects were mild, transient and well tolerated. Thus, adenosine thallium tomographic imaging provides a high degree of accuracy in the diagnosis of CAD. The use of the reinjection technique enhances the ability to detect reversible defects.