Does titanium cage subsidence affect clinical outcomes in ACDF surgery? A tertiary centre experience

BACKGROUND

Cage subsidence after anterior cervical discectomy and fusion (ACDF) surgery has been well documented with rates of up to 40%. Cages fill the void after cervical discectomy and promote fusion. These materials have different biomechanical profiles with differing rates of subsidence. This retrospective cohort study aimed to determine subsidence rates specifically associated with the novel Emerging Implant Technologies (EIT) titanium cage, identify risk factors associated with subsidence, and evaluate whether subsidence affects clinical outcomes.

METHODS

ACDF with insertion of stand-alone EIT cage was performed in 39 patients (64 levels) between December 2016 and February 2019 with a median follow-up of 11 months. Patients were classified into two groups; subsidence and non-subsidence, and were compared in terms of the resultant clinical outcomes as well as presence of risk factors. Health-related quality of life (HRQOL) outcomes were assessed using Visual Analogue Scale (VAS) for neck and arm pain, EuroQol 5-Dimension 5-Level (EQ-5D-5L), EuroQol Visual Analogue Scale (EQ VAS) and Neck Disability Index (NDI) scores.

RESULTS

Cage subsidence (>3mm) was present in nine patients (23%), which corresponded to ten levels treated (16%). Development of subsidence was not associated with gender (p = 0.12), age (p = 0.27), smoking (p = 0.13), number of treatment levels (p = 0.10) or cage size used (p = 0.34). It had no effect on any of the HRQOL outcomes, namely VAS Neck (p = 0.07), VAS Arms (p = 0.08), EQ-5D-5L (p = 0.36), EQ VAS (p = 0.85) and NDI (p = 0.80).

CONCLUSIONS

The EIT cage seems to be associated with lower rates of subsidence compared with other cage types. Cage subsidence was not associated with HRQOL outcomes or risk factors.

Exercise capacity as a predictor of coronary microvascular dysfunction

Introduction

Exercise capacity (EC) is an important prognostic test in patients with coronary artery disease (CAD). Positron-emission tomography (PET) is an important risk-stratifying tool to tailor management of patients with coronary artery disease.

Purpose

We aimed to assess EC in predicting positron emission tomography (PET) myocardial perfusion imaging (MPI) derived coronary flow reserve (CFR).

Methods

Consecutive patients who had clinically indicated PET MPI and EC were included. EC was defined based on peak metabolic equivalents (METS) achieved during exercise stress test. Myocardial blood flow (MBF) in ml/gm/min was obtained from dynamic PET MPI images at rest and peak hyperemia. The coronary flow reserve (CFR) was calculated as the ratio of stress to rest MBF of the left ventricle.

Results

The study population consisted of 511 patients who underwent PET MPI and EC testing (mean age 56 (±11), 71% male). Cardiovascular risk factors were prevalent (75% hypertensive, 82% dyslipidemic, 43% diabetics, 27% known CAD). Peak METS >6 was achieved in 81% of patients, and the CFR <2 was present in 27%. In multivariable logistic regression models adjusted for age, sex, cardiovascular risk factors (hypertension, diabetes, dyslipidemia) and medication use (angiotensin converting enzyme inhibitor/angiotensin receptor blocker, statins, beta-blockers), patients with peak METS >6 had a statistically significant lower odds of microvascular dysfunction (CFR <2: OR 0.43, 95% CI 0.26–0.71, p=0.001). Assessment of discrimination showed the model with CFR <2 had an incremental improvement of Harrell's C statistic over clinical variables (0.65 vs 0.69, p=0.02).

Conclusion

Our findings showed exercise capacity was a good predictor of CFR and microvascular coronary health over and above clinical variables. Further studies are needed to assess the prognostic interplay between EC and CFR.

Funding Acknowledgement

Type of funding sources: None.

Prognostic value of coronary flow reserve and coronary calcification in patients with suspected coronary artery disease

Introduction

Current cardiac PET and computed tomography imaging allows the simultaneous acquisition of anatomic and physiological data for patients suspected of CAD.

Purpose

We aimed to evaluate the incremental prognostic value of coronary artery calcium (CAC) score and coronary flow reserve (CFR) in patients with suspected coronary artery disease (CAD) undergoing positron emission tomography (PET) myocardial perfusion imaging (MPI).

Methods

We included consecutive patients who underwent PET MPI and CAC score calculation at Houston Methodist Hospital between August 2019 and January 2022. MPI and CAC scores were obtained in the same setting. The primary endpoint of the study was MACE. Cox proportional hazard regression was used to assess the incremental prognostic value of CAC and CFR by sequentially adding the variables to a model that included clinical and PET variables.

Results

A total of 2,072 patients (mean age 65.7±11.6 years, 54.7% women) were included in the analysis. Risk factors were prevalent (86.1% hypertension, 75.2% dyslipidemia, 45.5% diabetes). In total, 25.3% of the cohort had a CAC score of 0, 38.1% had CAC ≥400, and 39.9% had CFR <2. Over a median follow up of 6.26 (IQR 1.7–12.4) months, 66 (3.2%) patients had cardiac death/nonfatal myocardial infarction. CFR score added incremental prognostic value over clinical and perfusion variables alone (base model: c-index 0.75; Akaike information criterion [AIC]: 1,860.6; p<0.001; CFR model: c-index 0.78; AIC: 1,842.4; p=0.041). However, CAC score did not show an increased prognostic utility (CAC model: c-index 0.76; AIC: 1,854.8; p=0.087 vs. base model), and neither did the combined model of CAC and CFR scores (c-index 0.79; AIC: 1,839.4; p=0.366 vs. CFR model).

Conclusions

Among patients referred for PET MPI, CFR score added an increased prognostic value over clinical and MPI variables. However, when evaluating the prognostic utility of CAC alone, or of CAC and CFR combined, the multivariable model did not show any increased prognostic potential.

Funding Acknowledgement

Type of funding sources: None.

Incremental prognostic value of coronary flow reserve derived from SPIM digital positron emission tomography

Introduction

Positron emission tomography (PET) myocardial perfusion imaging (MPI) is an established test in the diagnosis and prognosis of patients with cardiac diseases. Silicon photomultiplier (SiPM) digital PET is the latest advancement in this technology with improved detector sensitivity, coincidence time resolution, and spatial resolution, allowing for Sub-milliSievert cardiac PET MPI.

Purpose

We aimed to assess the independent and incremental prognostic value of SiPM digital PET derived coronary flow reserve (CFR) to clinical and nuclear variables.

Methods

Consecutive patients who had clinically indicated digital Rubidium PET MPI were included. Rubidium dose was 10–20 mCi according to patient's weight. Patients were followed from the date of imaging to incident major adverse cardiovascular event (MACE: inclusive of all-cause death, myocardial infarction, admission for heart failure and late revascularization – percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) >90 days after imaging).

Results

The study population consisted of 2,893 patients with clinically indicated PET MPI (mean age 67 (±12), 53% male, 41% Caucasian). Cardiovascular risk factors were prevalent (88% hypertensive, 80% dyslipidemic, 47% diabetics, 18% ever smoking). After a mean follow-up of 8±7 months, 250 patients (8.6%, 10.7 per 1000 person-year) experienced MACE (90 D / 38 MI / 51 PCI / 11 CABG / 113 HF). In nested multivariable cox models, CFR was independently associated with incident MACE (HR 0.38, 95% CI 0.29–0.51, p<0.001) and incrementally improved risk prediction (Harrell's C=0.77, p=0.002).

Conclusion

Our findings showed that a Sub-milliSievert SiPM digital PET-derived CFR provided incremental value in risk-stratifying patients and identifying those at increased risk of incident outcomes.

Funding Acknowledgement

Type of funding sources: None.

Left ventricular volumes on positron emission tomography: validation against cardiovascular magnetic resonance

Introduction

Cardiovascular magnetic resonance (CMR) is the gold standard for determination of left ventricular volumes (LVV), including end diastolic volume (LVEDV) and end systolic volume (LVESV). With incorporation of ECG gating, the quantitative analysis of ventricular function can be achieved in Positron Emission Tomography (PET) studies. However, the accuracy of LVV quantification using PET has not been shown in previous studies.

Purpose

We aimed to assess the inter-study variability of LVEDV and LVESV between CMR and PET.

Methods

Consecutive patients who underwent both PET and CMR within 1 year were identified from prospective institutional registries. LVV on PET was compared against CMR as a reference standard using several statistical measures of agreement.

Results

The study population consisted of 233 patients (mean age 60.8±13.6 years, 64.8% male). The median (IQR) duration between CMR and PET was 41 (11–96) days. The median (IQR) LVEDV values were 144 (107–196) on PET and 178 (138–236) on CMR (mean difference 36.09±2.36, p<0.001). As shown in Figure 1, there was a good correlation (Spearman rho=0.88, p<0.001; Intraclass Correlation Coefficient 0.88, 95% CI 0.84–0.90, P<0.001) with moderate limits of agreement (95% limits of agreement −108.17–35.99). A total of 0% and 3.9% of the cohort had LVEDV >150 ml/m2 by CMR and PET respectively. Overall results were similar with LVESV values and similar in subgroup analysis of patients with a low EF (<40%), a coronary artery disease scar, LV hypertrophy and of patients with defibrillators.

Conclusion

Our analysis has shown a good correlation of LVV between PET and CMR, indicating PET derived LVV can accurately be used in the diagnosis and management of patients.

Funding Acknowledgement

Type of funding sources: None.

Prognostic value of PET derived coronary flow reserve: should we correct for resting perfusion product?

Introduction

Positron emission tomography (PET) myocardial perfusion imaging (MPI) derived coronary flow reserve (CFR) is an important risk-stratifying tool to tailor management of patients with coronary artery disease. Resting myocardial blood flow (MBF) is positively correlated to the product of resting heart rate and systolic blood product (resting pressure product – RPP), and can in turn lead to lower CFR in the setting of normal stress MBF.

Purpose

We aimed to assess the comparative incremental prognostic value of uncorrected to RPP-corrected CFR in predicting incident events.

Methods

Consecutive patients who had clinically indicated PET MPI were included. Patients were followed from the date of imaging to incident major adverse cardiovascular event (MACE: inclusive of all-cause death, myocardial infarction, admission for heart failure and late revascularization – percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) >90 days after imaging).

Results

The study population consisted of 2,893 patients with clinically indicated PET MPI (mean age 67 (±12), 53% male, 41% Caucasian). Cardiovascular risk factors were prevalent (88% hypertensive, 80% dyslipidemic, 47% diabetics, 18% ever smoking). After a mean follow-up of 8±7 months, 250 patients (8.6%, 10.7 per 1000 person-year) experienced MACE (90 D/38 MI/51 PCI/11 CABG/113 HF). Both uncorrected and corrected CFR were independently associated with incident MACE (HR 0.38, 95% CI 0.29–0.51, p<0.001 and 0.61, 95% CI 0.50–0.76, p<0.001 respectively). A comparison of model incremental prognostic value showed the model with uncorrected CFR had a statistically higher Harrell's C (0.76 vs 0.77, p=0.23).

Conclusion

Our findings showed that the prognostic value of CFR was preserved even in the setting of high resting blood pressure or heart rate. This suggests that correction for RPP should be selective.

Funding Acknowledgement

Type of funding sources: None.

Coronary microvascular health in patients with prior COVID-19 infection and no known CAD

Introduction

Although most patients recovering from acute COVID-19 infection have complete resolution of symptoms, some have cardiopulmonary symptoms lingering long after the acute phase of the disease. One proposed mechanism involves chronicity of COVID-19 associated with myocarditis and endotheliopathy.

Purpose

To determine the coronary microvascular health of patients with prior COVID-19 and no known coronary artery disease (CAD) using positron emission tomography (PET).

Methods

Cases consisting of patients without known CAD but previous COVID-19 infection who had clinically indicated PET imaging were matched 1:4 on clinical and cardiovascular risk factors to controls having no prior COVID-19 infection. Myocardial blood flow (MBF) in ml/gm/min was obtained from dynamic images at rest and peak hyperemia. The coronary flow reserve (CFR) was calculated as the ratio of stress to rest MBF of the left ventricle. Coronary microvascular dysfunction (CMD) was defined as CFR<2.

Results

The study population consisted of 315 patients, 25% (n=80) of which had prior COVID-19 infection (mean±SD age 64±11 years, 46% men). The median (IQR) number of days between COVID-19 infection and PET imaging was 190 (85–268) days. After adjusting for age, gender and cardiovascular risk factors, patients with prior COVID-19 and no known CAD had a statistically significant higher odds of having a CFR <2 (OR 4.9, 95% CI 2.3–10.1 p<0.001) and CFR <2 normalized to patient's rate-systolic blood pressure product (OR 2.8, 95% CI 1.6–5.0 p=0.001). The annualized event rate for the composite outcome of all-cause death, myocardial infarction, admission for heart failure exacerbation and late revascularization was higher in cases vs controls and in those with CMD.

Conclusion

Our analysis showed that patients with prior COVID-19 and no known CAD had higher rates of CMD, and that the presence of CMD was associated with higher risk of incident cardiovascular events.

Funding Acknowledgement

Type of funding sources: None.

Comparative prognostic utility of visual grade and heart-to-contralateral lung ratio in patients undergoing 99mTc-pyrophosphate radiotracer cardiac scintigraphy

Introduction

Transthyretin (ATTR) cardiac amyloidosis (CA) is an underdiagnosed form of restrictive cardiomyopathy leading to a rapid progression into heart failure. 99mTc-labeled radiotracer cardiac scintigraphy is crucial for the evaluation of CA. Semiquantitative (Perugini visual grade) and quantitative (heart-to-contralateral lung ratio, H/CL) parameters are used to assessing CA via cardiac scintigraphy.

Purpose

We aimed to assess the comparative prognostic utility of the Perugini visual grade and heart to contralateral lung ratio.

Methods

The study population was identified based on an institutional registry of consecutive patients undergoing 99mTc-PYP radiotracer cardiac scintigraphy for suspected CA between January 2020-October 2021. The H/CL is calculated by the fraction of heart region of interest (ROI) mean uptake counts to the contralateral chest ROI. The visual scoring system compares uptake between bone (rib) and heart where 0 = absent cardiac uptake, 1 = uptake less than bone, 2 = uptake equal to bone, and 3 = is uptake greater than bone. Ejection fraction (EF) was obtained from echocardiographic studies done around the time of cardiac scintigraphy. MACE was defined as a composite of inclusive of all-cause death, myocardial infarction, admission for heart failure and late revascularization – percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) >90 days after imaging.

Results

A total of 330 patients (mean age 70.9±12.2 years, 62.2% male) were included in the analysis. Risk factors were prevalent (59.7% hypertension, Heart Failure 68.3%, 26.5% dyslipidemia, 26.2% diabetes) (Table 1). In total, 32.6% of the cohort had studies suggestive of ATTR CA. Median time between echocardiography and cardiac scintigraphy was 7 days (IQR 5–42 days). A higher frequency of MACE was reported in patients with a 2+ visual grade (30% vs 42%, p=0.03). A H/CL >1.5 was associated with borderline significance (43% vs 35% p=0.07).

Conclusion

Our analysis showed that the Perugini visual grading of transthyretin cardiac amyloidosis conferred the best prognostic utility contrary to heart to contralateral lung ratio in 99mTc-PYP radiotracer cardiac scintigraphy.

Funding Acknowledgement

Type of funding sources: None.

Outcome of sedentary patients: does the power of zero cac make a difference?

Introduction

Coronary artery calcium score (CACS) and exercise capacity (EC) are both independent prognostic tests in coronary artery disease (CAD).

Purpose

We aimed to assess the incremental prognostic role of EC to CACS, particularly in those with absent or low coronary calcification.

Methods

The cohort consisted of patients who had clinically indicated exercise stress testing and CACS assessment with a median of 27 days of each other. EC was defined based on peak metabolic equivalents (METS) achieved during exercise stress test. CACS was determined using the Agatston method. Patients were followed from the latest test date to incident MACE (inclusive of all-cause death, non-fatal myocardial infarction, late revascularization and admission for heart failure).

Results

There were a total of 1932 patients in the study population (mean age 56±12, 42% female, 48% hypertension, 21% diabetes, 48% dyslipidemia). Peak METS <6 was achieved in 8% of patients, and the median (IQR) CACS was 9 (0–203). Patients with EC <6 METS had doubling of their event rate across strata of CACS, even amongst patients with absent or low coronary calcifications (CACS 0: 4.6 vs 10.9; CACS 1–99: 10.4 vs 20.4; MACE per 1000 person year in patients with peak METS ≥ vs <6 respectively) (Figure 1).

Conclusion

Our findings showed that poor exercise capacity was associated with higher risk even in patients with absent or low coronary calcification.

Funding Acknowledgement

Type of funding sources: None.

Racial disparities of internet access in the united states: a multiyear analysis of the national behavioral risk factors surveillance system

Introduction

The COVID 19 pandemic has led to a dramatic rise in the use of Telehealth. Studies have shown racial/ethnic disparities in internet access, a basic prerequisite for telehealth. However, little is known on the extent of this “digital divide” amongst racial minorities with cardiovascular comorbidities.

Purpose

To investigate racial disparities in internet access amongst those with cardiovascular diseases and risk factors, and explore the degree to which this exists amongst those with different levels of comorbidities.

Methods

Behavioral Risk Factors Surveillance System data from the years 2013–2017, during which survey respondents were asked the main outcome of interest (“Have you used the internet in the past 30 days”) were pooled. Respondents were included if they responded yes to questions on selected cardiovascular diseases and risk factors of interest. Multivariable logistic regression was used to analyze the odds of internet use by racial groups adjusting for several socioeconomic factors.

Results

There were a total of 1,478,214 individuals representing 150,235,244 million adults (non-Hispanic Blacks 11.31% and Hispanics 13.75%). Hispanics and Non-Hispanic Blacks reported the lowest prevalence of internet use (66.1% and 64.4% respectively) compared to Non-Hispanic Whites (81.9%). On regression analysis, racial minorities consistently reported lower rates of internet use, averaging 50% lower odds compared to non-Hispanic Whites. Results remained statistically significant even after controlling for several sociodemographic variables.

Conclusion

Using a large nationally representative cohort, we demonstrated differences in internet access amongst racial minorities and those with multiple comorbidities, placing them at distinct disadvantage with access to telecare. Our study adds to a growing body of literature that shows the disproportionate impact of the pandemic on minorities and calls for a concerted effort to reduce disparities in healthcare delivery.

Funding Acknowledgement

Type of funding sources: None.

Prognostic value of computed tomography derived fractional flow reserve

Introduction

Cardiac computed tomography angiography (CCTA) derived fractional flow reserve (FFRCT) has been shown to add incremental diagnostic value by providing functional severity of coronary lesion in patients with coronary artery disease (CAD).

Purpose

We aimed to assess the prognostic value of FFRCT in patients with suspected CAD.

Methods

Consecutive patients who had clinically indicated CCTA and FFRCT determination at a tertiary care cardiology practice were included. FFRCT was determined off-site using computational flow dynamics. Patients were followed for major adverse cardiovascular events (MACE, inclusive of all-cause death, non-fatal myocardial infarction, and late percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG) 90-days after imaging test.)

Results

A total of 667 patients with at least Coronary Artery Disease Reporting & Data System (CAD-RADS) 2 were included. Mean age was 68±10 years, 37% were women, 73% had hypertension, 12% had diabetes and 61% had dyslipidemia. More than half (57%) of the patients had moderate (CAD-RADS 3) stenosis. FFRCT<0.8 was found in 59% of patients, with increasing percent across categories of CAD-RADS. After a median follow-up of 9 months, 52 patients (7.2%, 6.7 events per 1000 person-year) experienced a MACE. In multivariable Cox regression models adjusted for age and sex, FFRCT <0.8 significantly predicted outcomes (HR 2.48 95% CI 1.26–4.87 p=0.008). Sensitivity analysis using lower thresholds of FFRCT failed to show similar results in intermediate stenosis.

Conclusion

Our results suggest that in a real-world cohort of patients with suspected CAD, FFRCT can identify patients at higher risk of incident cardiovascular outcomes.

Funding Acknowledgement

Type of funding sources: None.

Added prognostic value of plaque burden to computed tomography angiography anatomic assessment and myocardial perfusion imaging in patients with diabetes Mellitus

Introduction

Cardiac computed tomographic angiography (CCTA)-derived measures of coronary artery disease (CAD) burden such as segment involvement score (SIS), which quantifies the number of segments with plaque, have been shown to independently predict incident cardiovascular events.

Purpose

We aimed to compare the added prognostic value of plaque burden to CCTA anatomic assessment and single photon emission computed tomography (SPECT) physiologic assessment in patients with diabetes undergoing both tests.

Methods

Consecutive patients with diabetes who underwent clinically indicated CCTA and SPECT myocardial imaging for suspected coronary artery disease at a tertiary care center were retrospectively identified from medical records. Stenosis severity and segment involvement score (SIS) were determined from CCTA, and presence of ischemia was determined from SPECT. Patients were followed from date of imaging for major adverse cardiovascular events (MACE; inclusive of all-cause death, non-fatal myocardial infarction, and percutaneous coronary intervention or coronary artery bypass grafting 90-days after imaging test.)

Results

A total of 778 patients were included (mean age 60.6±14.4 years, 55% males). Obstructive stenosis (left main ≥50%, all other coronary segments ≥70%) and ischemia were found in 15% and 16% of patients respectively. After a median follow-up of 31 months, 87 (11%) patients experienced a MACE. In multivariable Cox regression models, SIS significantly predicted outcomes in models including obstructive stenosis and ischemia (HR 1.17, 95% CI 1.10 - 1.24, p<0.001; 1.16, 95% CI 1.10 - 1.23, p<0.001). The addition of SIS also significantly improved discrimination (Harrel's C 0.75, p=0.006; 0.76, p=0.006 in models with CCTA obstructive stenosis and SPECT ischemia respectively). Results were consistent using subgroups of summed scores by composition of plaque (calcified vs non-calcified) and alternate definitions of obstructive stenosis.

Conclusion

Our results suggest that in high-risk patients with diabetes and suspected coronary disease, SIS has incremental prognostic value over ischemia by SPECT or stenosis by CCTA in predicting incident cardiovascular outcomes.

Funding Acknowledgement

Type of funding sources: None.

Incremental prognostic value of calcified vs non-calcified plaque burden on computed tomography angiography and myocardial perfusion imaging

Funding Acknowledgements

Type of funding sources: None.

Background

Coronary computed tomography angiography (CCTA) is currently guideline-endorsed for diagnosing suspected coronary artery disease (CAD) in low-intermediate risk patients. Single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) has an established role in both the accurate detection of ischemia and identification of patients at high risk of future cardiovascular events. Recent studies have shown that the burden of atherosclerotic plaque is an independent predictor of cardiovascular events, and that this effect depends on the degree of calcification.

Purpose

To compare the incremental prognostic value of calcified vs non-calcified plaque burden to CCTA anatomic assessment and SPECT physiologic assessment in patients evaluated with both tests.

Methods

Consecutive patients who underwent clinically indicated CCTA and SPECT myocardial imaging for suspected CAD were included. Ischemia on SPECT was defined as summed difference score > 0 using perfusion graded on a 5-point scale. Anatomically obstructive CAD by CCTA was defined as ≥50% in the left main artery and ≥70% stenosis severity in proximal, mid and distal branches of the left anterior descending, left circumflex and right coronary artery without including side branches. Segment involvement score was defined as the sum of segments with plaque irrespective of the degree of stenosis using an 18-segment coronary artery model. A Hounsfield unit threshold of > =130 was used to classify plaques composition as calcified/mixed (C-SIS) vs non-calcified plaque (NC-SIS). Patients were followed for major adverse cardiovascular events (MACE, inclusive of all-cause death, non-fatal myocardial infarction, and percutaneous coronary intervention or coronary artery bypass grafting 90-days after imaging test.)

Results

A total of 956 patients were included. (Mean age 61.1 ± 14.2 years, 54% men, 89% hypertension, 81% diabetes, 84% dyslipidemia). Obstructive stenosis (left main ≥ 50%, all other coronary segments ≥ 70%) and ischemia were observed in similar number of patients (14%). After a median follow-up of 31 months, 102 patients (11%, 29.2 events per 1000 person-year) experienced a MACE. In multivariable Cox regression models, C-SIS, but not NC-SIS significantly predicted outcomes and improved risk discrimination in models with CCTA obstructive stenosis (HR 1.14 95% CI 1.08 - 1.20 p= <0.001; Harrel’s C 0.74, p = 0.011) and SPECT ischemia (HR 1.14 95% CI 1.08 - 1.20, p < 0.001; Harrel’s C 0.76, p = 0.015).

Conclusion

In the current study of high-risk patients with suspected CAD, calcified plaque burden, but not non-calcified plaque incrementally added to measures in predicting incident cardiovascular outcomes

Inter-operator reliability of an onsite machine learning-based prototype to estimate CT angiography-derived fractional flow reserve

Funding Acknowledgements

Type of funding sources: None.

Background

Advances in computed tomography (CT) and machine learning have enabled on-site non-invasive assessment of fractional flow reserve (ML-FFRCT). However, reproducibility of measurements across operators is not well demonstrated.

Purpose

This study was designed to measure the inter-operator variability and reproducibility of Coronary CT Angiography–derived fractional flow reserve values using a post-processing prototype based on a machine learning algorithm (ML-FFRCT).

Methods

We included 60 symptomatic patients who underwent coronary CT angiography. FFRCT was calculated by 2 independent operators after training using a machine learning based on-site prototype. FFRCT was measured 1 cm distal to the coronary plaque or in the middle of the segments if no coronary lesions were present.  Intraclass correlation coefficient (ICC) and Bland-Altman analysis were used to evaluate inter-operator variability effect in FFRCT estimates. Sensitivity analysis was done by cardiac risk factors, degree of stenosis and image quality.

Results

A total of 535 coronary segments in 60 patients were assessed. The overall ICC was 0.986 per patient (95% CI: 0.977 - 0.992) and 0.972 per segment (95% CI: 0.967 - 0.977). The absolute mean difference in FFRCT estimates was 0.012 per patient (95% CI for limits of agreement: -0.035 - 0.039) and 0.02 per segment (95% CI for limits of agreement: -0.077 - 0.080). Tight limits of agreement were seen on Bland-Altman analysis. Distal segments had greater variability compared to proximal/mid segments (absolute mean difference 0.011 vs 0.025, p < 0.001). Sensitivity analysis showed similar results across degrees of stenosis, image quality and those with cardiac risk factors such as hypertension, diabetes and dyslipidemia.

Conclusion

A high degree of inter-operator reproducibility can be achieved by onsite machine learning based ML-FFRCT assessment. Future research is required to evaluate the physiological relevance and prognostic value of ML-FFRCT.

The prognostic role of PET myocardial perfusion imaging in patients with cardiac sarcoidosis: a systematic review

Funding Acknowledgements

Type of funding sources: None.

Background

Sarcoidosis is a multi-systemic inflammatory disease of unknown etiology. Cardiac Sarcoidosis (CS) has been reported in as much as 25% of patients with systemic involvement. 18Fluorodeoxyglucose (FDG) Positron Emission Tomography (PET) has a high diagnostic sensitivity/specificity in the diagnosis of CS.

Purpose

The aim of this review is to summarize evidence on the prognostic role of FDG PET.

Methods

Studies were identified by searching MEDLINE from inception to October 2020. Medical Subject Headings (MeSH) terms for sarcoidosis; cardiac and FDG PET imaging were used. Studies of any design assessing the prognostic role of FDG PET in patients with either suspected or confirmed cardiac sarcoidosis imaging done at baseline were included. Abnormal PET was defined as abnormal metabolism (presence of focal or focal-on-diffuse uptake of FDG) OR abnormal metabolism and a perfusion defect. Studies reporting any outcome measure were included. Pooled risk ratio for the composite outcome of MACE was done.

Results

A total of 6 studies were selected for final inclusion (515 patients, 53.4% women, 19.8% racial minorities.) Studies were institution based, retrospective in design and enrolled consecutive patients. All were observational in nature and published in English. All studies used a qualitative assessment of PET scans (abnormal FDG uptake with or without abnormal perfusion). Two studies assessed quantitative metrics (summed stress score in segments with abnormal FDG uptake, standardized uptake value and cardiac metabolic activity.) All studies reported Major Adverse Cardiovascular Events (MACE) as a composite outcome. After a mean follow up ranging from 1.4 to 4.1 years, there were a total of 105 MACE. All studies included death (either all-cause death or sudden cardiac death) and ventricular arrhythmia (ventricular tachycardia or ventricular fibrillation) as a component of MACE. Four of the six studies adjusted for several characteristics in their analysis. All four studies used Left Ventricular Ejection Fraction (LVEF). However, other adjustment variables were not consistent across studies. Five studies found a positive prognostic association with the primary outcome, two of which assessing right ventricular uptake.

Conclusion

Although available evidence indicates FDG PET can be used in the risk stratification of patients with CS, our findings show further studies are needed to quantify the effect in this patient group.

P26 Bridging the gap – benefits of neurosurgical tissue for pre-clinical research

Objectives

The use of primary human neural tissue for research provides an invaluable insight into human neural function that cannot be achieved in any other way. Despite this it is successfully collected and used in only a small minority of units. We have established a collaboration between Neurosurgical Unit and the University that allows us to study using human tissue resected during neurosurgery. Tissue is most commonly collected from oncological, epilepsy and vascular operations. Here we share our experiences of the practicalities and try to provide some insights for practicing neurosurgeons.

Subjects

We discuss the practical difficulties of the co-ordination of the clinical and academic teams, and challenge of optimization of the tissue for the research. We will present the mechanisms in place to optimize the study of human neural tissue. We will review the progression from resection of limited tissue to any neurosurgical procedure in which the normal brain is resected and tissue discarded. We discuss the different models that can be used and the application locally to glioma stem cells, pathways activated in TBI and the electrophysiology of the normal brain.

Conclusions

We will present examples of the value of human tissue studies, including electrophysiological differences between humans and rodent that could only be investigated through the use of live human tissue. We will also demonstrate how we have moved to streamline tissue collection and propose a move to establish a national framework.

Retroperitoneal Varix ligation with sclerotherapy: a prospective randomized comparative study

Introduction

The aim of this article is to compare the results of high varix ligation with and without sclerotherapy.

Material and methods

Between November 2014 and December 2015, sixty patients with varicocele were included in this study. Patients were divided into two equal groups; group I (underwent high varix ligation), and group II (underwent high varix ligation with a retrograde injection of 2 mL of 5% ethanolamine oleate in the lower end of the bisected gonadal vein). The operative time, intra- and postoperative complications, postoperative pain, improvement of semen parameters, incidence of recurrence and achieving of unassisted pregnancy were recorded for both groups.

Results

The age range was 19-34 years in group I and 21-37 years in group II. The operative time was shorter in group I (34.6 ±7.81 min) than group II (43.3 ±8.5 min) (P <0.001), which was statistically significant.Improvement of semen parameters and the occurrence of spontaneous pregnancy were insignificant between both groups. No intraoperative complications occurred. The postoperative complications were statistically insignificant in both groups.

Conclusions

Combined varix ligation with retrograde sclerotherapy does not offer significant advantages over high varix ligation alone with a longer operative time and prolonged post-operative pain.

Molecular epidemiology of avian influenza virus and incidence of H5 and H9 virus subtypes among poultry in Egypt in 2009-2011

Egypt has experienced outbreaks of avian influenza (AI) since 2006. A total of 3583 cloacal swabs were collected from chickens, ducks, geese and turkeys from commercial farms, backyards and local bird markets in Qena and Luxor governorates in South Egypt during 2009-2011. These samples were examined for the presence of AI virus (AIV) and positive samples were further subtyped for the H5 and H9 by real time RT-PCR. In this way, 202 (5.64%) samples were found to be AIV-positive of which 186 (92.08%) and 7 (3.46%) belonged to H5 and H9 subtypes, respectively. Higher infection rates were observed in backyard birds and birds from local bird markets in comparison to birds from commercial farms. In conclusion, the predominance of H5 infection indicates a need for continuous monitoring of AIV among avian species and the awareness against public health risk.

Decompressive craniectomy for acute disseminated encephalomyelitis

BACKGROUND

Acute disseminated encephalomyelitis (ADEM) is a rare, acute demyelinating condition. Although it usually presents in an acute or subacute manner over days, its clinical course may be rapid with symptoms and signs of severe intracerebral mass effect secondary to cerebral oedema.

METHODS

Case report and literature review.

RESULTS

We report a case of a patient presenting with a hyperacute course manifested by rapid loss of consciousness and focal neurological signs. Management with emergency hemicraniectomy and steroids resulted in rapid neurological improvement and minimal long-term deficit.

CONCLUSIONS

We believe that only surgical decompression is likely to be life saving in similar cases of hyperacute cerebral oedema due to ADEM. The wide decompression performed was concordant with that indicated for traumatic brain swelling. Such aggressive management is vindicated by the rapid recovery shown by our patient within days of surgery and the finding of minimal neurological sequelae at 3 months.

Review of 3,530 referrals for bone density measurements of spine and femur: evidence that radiographic osteopenia predicts low bone mass

PURPOSE

To determine the relationship between bone mineral density (BMD) measurements and the initial reason for referral to a BMD screening service.

MATERIALS AND METHODS

Referral letters for 3,479 of the 3,530 women referred for BMD screening were classified according to the indication for screening. Mean age-matched standard deviation scores (Z scores) were derived for each of the 10 most common indications. Mean BMD between each group was compared with the age-matched value from the local normal range by means of a one-sample Student t test. Mean young normal standard deviation scores (T scores) were derived, and the percentages of women with osteopenia or osteoporosis from each referral group were calculated on the basis of the World Health Organization criteria.

RESULTS

The most common reason for referral was to aid in a decision regarding hormone replacement therapy (n = 700). The highest proportion of women with osteoporosis in any group was in the radiographic osteopenia group (n = 269).

CONCLUSION

Radiographic evidence of osteopenia is a strong predictor of osteoporosis. Screening for osteopenia appears justified in this and other high-risk groups and those seeking a rationale for preventive therapy.

Screening for osteopenia and osteoporosis: do the accepted normal ranges lead to overdiagnosis?

Osteoporosis is a common disease which causes significant morbidity and mortality and in many cases may be preventable. In the absence of fragility fractures the accepted method of identifying those at high risk is based upon bone mineral density (BMD) measurements with defined cut-off points. To correctly delineate normal from abnormal, reliable reference ranges appropriate to the observed population are required. We have studied the age-dependent changes in mean BMD and standard deviation at the lumbar spine and femoral neck in a normal population extracted from 4280 women screened for osteopenia and compared our findings with the manufacturer's normal range (MNR). The recent World Health Organization criteria for the diagnosis of osteopenia and osteoporosis using the 'manufacturer's young normal' (MYN) values and our 'study young normal' (SYN) values have been applied. The study normal population (SNP) included 2068 women (mixed social class; mean age 53 years, range 30-79 years). The distribution of mean lumbar spine BMD with age in SNP was generally similar to the MNR. In contrast mean femoral neck bone density from SNP was significantly different from the MNR, ranging from 3% to 12% lower in each 5-year group analysed (p < 0.05). Comparison of standard deviations in spine BMD in SNP against the fixed MNR standard deviation showed a statistically significant increase commencing at 45 years of age. The magnitude of this increase appeared to rise with age and remained significant in the 75- to 79-year age group (p < 0.05). In contrast, standard deviation in femoral neck BMD in SNP appeared relatively constant with age except in the group of women at and around the time of the menopause. The SYN value for mean lumbar spine BMD was 0.994 g/cm2 (cf. MYN value 1.047, p < 0.0001) with a standard deviation of 0.122 g/cm2 (cf. MYN 0.11, p = 0.0005). Similarly our SYN value for femoral neck BMD was 0.787 (cf. MYN value 0.895, p < 0.0001) with a standard deviation of 0.109 (cf. MYN value 0.10, p = 0.0027). Using SYN values 36% (748) for the spine and 33% (675) for the hip of our normal population are classified as osteopenic or osteoporotic. Using MYN values increases the proportion of women classified as osteopenic or osteoporotic to 52% (1078) for the spine and 68% (1409) for the femur. If both sites of measurement are considered simultaneously SYN classifies 46% (952) as either osteopenic or osteoporotic at one or other site, which is increased to 73% (1513) when the MYN values are used. We observe that manufacturer's reference ranges may not be appropriate for the local population and may lead to an erroneously high diagnosis of osteopenia and osteoporosis, which would lead to unnecessary patient anxiety and perhaps errors regarding treatment.

Hormone replacement therapy and serum angiotensin-converting-enzyme activity in postmenopausal women

The mechanisms by which hormone replacement therapy (HRT) reduces the risk of coronary heart disease (CHD) are incompletely understood, but may include direct arterial effects. We examined the effect of oestrogen/progestagen HRT on serum angiotensin-converting-enzyme (ACE) activity in postmenopausal women. After 6 months, ACE activity was reduced by 20% (p < 0.001) on average in 28 treated women but remained unchanged in 16 controls. Serum ACE activity is modifiable by gonadal steroids and changes in serum ACE may represent a novel mechanism by which HRT reduces CHD risk in women.

Prolonged pregnancy

The perceived risks to the fetus of the postmature syndrome have led to the obstetrician's dilemma of whether to await spontaneous parturition or to artificially bring forward the onset of labor to an arbitrarily defined gestation. A prolonged or post-term pregnancy relates to a gestation of greater than 42 weeks and should not be regarded as synonymous with postmaturity. The latter describes a clinical syndrome thought to be a consequence of failing placental function. It is the difficulty in identifying the 'at risk' fetus which has led to routine induction policies. But is such a policy justified in terms of fetal outcome, and if so, is the mother put at increased risk? This review puts into perspective the most recent publications and points out areas requiring further study.

Trypanosome infection rate of Glossina morsitans submorsitans in Bahr El Arab, South Darfur Province, Sudan

Trypanosome infection rate of Glossina morsitans submorsitans in Bahr El Arab fly belt, Sudan was investigated in four areas using fly rounds with screen and bait animals together with traps during the dry season February to May 1985. The overall infection rate of tests flies captured in the four areas was 5.1%. The infection rate of vivax group trypanosomes comprised 64.7% of total infections, congolense group 31.2% and brucei group trypanosomes 3.9%: 27.3% of the vivax and 31.3% of the congolense were immature trypanosome infections. Mixed trypanosome infections were encountered in a few flies. Trypanosome infection rate of flies differed with the sampling technique employed. A linear positive correlation existed between the physiological age of males and their trypanosome infection rates.

Ocular toxicity of desferrioxamine: light microscopic histochemical and ultrastructural findings

This study documents for the first time light and electron microscopical changes in the retinal pigment epithelium (RPE) following treatment with high dose desferrioxamine for systemic iron overload. The changes include loss of microvilli from the apical surface, patchy depigmentation, vacuolation of the cytoplasm, swelling and calcification of mitochondria, and disorganisation of the plasma membrane. In addition, Bruch's membrane overlying degenerate RPE cells appeared abnormally thickened owing to the accumulation of large amounts of mature elastic fibres, pre-elastic oxytalan, and long spacing collagen. The specificity of these changes and the mechanism of toxicity are discussed.

Lipid keratopathy and atheromatosis in an SPF laboratory rabbit colony attributable to diet

Sporadic cases of corneal opacity occurred in an SPF rabbit colony fed on a diet containing 10% white fish-meal. Routine histological monitoring also revealed atheromatous lesions involving the intima of the aorta, coronary arteries and the arteries of other organs in 29 rabbits examined. Serum cholesterol levels above 10 mmol/l were found in 7 rabbits, including 4 affected with corneal lesions, which proved to be lipid keratopathy on histochemical and electron microscopical examination. The serum cholesterol level was found to be within normal range (below 2.27 mmol/l) in 10 rabbits reared entirely on a modified version of the diet, where the 10% fish-meal content was replaced with 10% grass-meal. No more ocular or atheromatous lesions have been found since the adoption of the new diet for the colony.

Physiological and pathobiological significance of ocular glycoproteins. I. Studies using fluorescein labelled glycine max

Cell surface carbohydrates play an important role in several biological, immunological, and neoplastic phenomena including development, growth regulation, cellular locomotion, receptor activation, and tumour metastasis. Fluorescein labelled lectins which bind to specific carbohydrate residues in glycoproteins and glycolipids are being increasingly used as chemical probes to study cell components. Several different preparations of ocular tissues from human, rabbit, and rat were examined for the distribution of N-acetyl-D-galactosamine (D-gal NAc) by means of fluorescein-labelled lectin from soybean (glycine max). A very strong fluorescence was observed in the corneal epithelium; Descemet's membrane and corneal endothelium were also strongly fluorescent. The conjunctival epithelium similarly showed a strong reaction, as did the goblet cells. The iris epithelium and the dilator pupillae were only weakly fluorescent, but the ciliary body showed strong fluorescence, as did the blood vessels. As compared with lens fibres the lens epithelium was strongly fluorescent. The outer retina, that is, the photoreceptors, the pigment epithelium, and Bruch's membrane, showed a very strong reactivity. The optic nerve showed moderate fluorescence, but reaction with extraocular muscles was variable. The skin of the upper and lower eyelids, hair follicles, and blood vessels showed strong lectin binding. Sections of retinoblastoma and malignant melanoma showed no reaction. The physiological and pathological significance of these findings is discussed.

Intake and digestibility of berseem (Medicago sativa) and Sorghum Abu 70 (Sorghum vulgare) forages by Sudan zebu cattle and desert sheep

Two experiments were carried out with Sudan zebu cattle and desert sheep to study the voluntary intake and digestibility of berseem (Medicago sativa) and Abu 70 (Sorghum vulgare) forages when offered ad lib. alone and with supplements of molasses to the cattle and dura grain to the sheep. In both experiments the intake of berseem was significantly higher than Abu 70. Supplementation increased Abu 70 intake and while molasses significantly increased berseem intake by cattle, dura decreased its intake by sheep. On the basis of metabolic body size sheep showed a higher intake of these forages than cattle. There was no significant difference in DM digestibility between berseem and Abu 70 by cattle. Sheep digested berseem significantly better than Abu 70. Molasses and dura significantly increased the digestibility of Abu 70 by cattle and sheep but had no significant effect on the DM digestibility of berseem.

Formation of stable crystalline enzyme-substrate intermediates at sub-zero temperatures

Sub-zero temperatures can be used to trap intermediates in enzyme-catalysed reactions using suitable cryosolvents. The feasibility of obtaining such intermediates in the crystalline state for X-ray diffraction studies has been demonstrated with several proteases, using specific substrates and optimal pH.

Antifreeze glycoproteins from Antarctic fish. Inactivation by borate

Antifreeze glycoprotein, which has previously been shown to be inactive in the presence of borate, migrates electrophoretically as the borate complex, presumably through formation of borate complexes with hydroxyl groups on the sugar side chains. Antifreeze glycoprotein (5 mg/ml) has been found to be completely active in the presence of 0.1 M borate at pH 7, but inactive at pH 9. A titration curve of pH versus the antifreeze activity of glycoprotein (5 mg/ml) in 0.1 M borate showed a progressive decrease in antifreeze activity as the pH was increased. Concomitant with decreases in activity were increases in binding of borate. At pH 9.0, nearly 2 mol of borate were complexed per glycotripeptide. Ultracentrifuge analyses showed similar molecular weights and laser quasi-elastic light scattering showed similar diffusions at pH 7.0 and 9.0 in borate and in the absence of borate. The binding of borate, rather than a change in conformation, is thus directly related to the loss of antifreeze activity. Alkaline borate also decreased hemagglutinating activity of Osage orange lectin and decreased the inhibition of the activity by the antifreeze glycoproteins.

Antifreeze glycoproteins from an Antarctic fish. Quasi-elastic light scattering studies of the hydrodynamic conformations of antifreeze glycoproteins

A quasi-elastic light-scattering technique was used to study the hydrodynamic conformations of antifreeze glycoproteins from an Antarctic fish. Antifreeze glycoprotein is composed of repeating units of Ala-Ala-Thr, with each threonine O-linked to a disaccharide, and it exists as several polymers of different numbers of this repeating unit. Molecular weights of the two major active polymers are 10,500 and 17,500 by such methods as centrifugation and osmotic pressure, but smaller than 20 by freezing-point depression. Translational diffusion coefficients at 20 degrees were 8.35 times 10-7 cm2 s-1 and 6.15 times 10-7 cm2 s-1 for the M-r-10,500 and 17,500 polymers, respectively. Measurements at -0.2 degrees in the presence of ice crystals did not indicate any conformational changes that might be related to the lowering of the freezing temperature. Lowering the temperature of these glycoprotein solutions close to temperatures of freezing caused a decrease in the effective hydrodynamic radius of both active and inactive glycoprotein components.