Influence of non-invasive anatomical versus functional testing on physician certainty score among patients assessed within a rapid access chest pain clinic

Background

Recently, rapid access chest pain clinics (RACPC) have been shown to improve clinical and economic efficiency, with some well-established models adopting non-invasive anatomical testing (CTCA) as a universal first test. Physician certainty over the presence of significant coronary artery disease (CAD) and that symptoms are likely secondary to CAD, may influence management decisions. Data directly comparing the performance of anatomical versus functional testing, in regards to their influence on physician certainty scores, remains sparse.

Purpose

To assess the influence of non-invasive anatomical versus functional testing on physician certainty among patients attending a RACPC.

Methods

Patients attending our RACPC were invited to participate. Recruitment to the research registry was via written consent. Registry patients undergoing non-invasive anatomical (CTCA) or functional testing (myocardial perfusion imaging (MPS), exercise treadmill test (ETT) or stress echo (SE)) were included in the current analysis. Physician certainty scores (yes/likely/unlikely/no) were generated at baseline (pre-test) and post-test for all registry patients for (1) the presence of CAD and (2) angina secondary to CAD. Change in physician certainty (frequency and direction) post-test was identified and analysed to determine the influence of each testing modality.

Results

Between December 2015 and October 2021, 2541 patients attended RACPC, with 1542 patients recruited to the registry; mean age 57±12 years, 49% male, 16% typical angina, 30% atypical angina and 54% with non-anginal chest pain. Non-invasive anatomical or functional testing was performed in 1223 (79%) registry patients, with paired (pre and post-test) physician certainty scores available in 1184 (97%); 665 (56%) CTCA, 243 (21%) MPS, 210 (18%) ETT and 66 (5%) SE. Compared with functional testing, CTCA demonstrated a greater frequency of change in physician certainty scores for (1) presence of CAD (92% vs 58%, p<0.001) and (2) angina secondary to CAD (74% vs 61%, p<0.001), Figure 1. In addition, anatomical testing was also associated with greater differentiation in physician certainty for the presence of CAD; increased certainty, 47% vs 21% (p<0.001); decreased certainty, 44% vs 35% (p<0.01), with no change in certainty observed in only 8% anatomical vs 43% functional testing (p<0.001). Certainty for angina due to CAD was similar; increased certainty, 10% vs 8% (p=0.45); decreased certainty, 64% vs 53% (p<0.001); and no change 26% vs 38% (p<0.001), Figure 2.

Conclusion

Compared to functional testing, non-invasive anatomical testing resulted in greater frequency of change and increased differentiation of physician certainty. These observations suggest that non-invasive anatomical testing within a RACPC setting may significantly enhance diagnostic confidence, which may help guide management decisions.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): State Health Research Advisory Council (SHRAC)- Western Australia

480 Successful anticoagulation treatment of an ascending aortic thrombus associated with myocardial infarction and systemic embolism

Background

The ascending aorta is an uncommon site for non-infective mural thrombus. The detection of such a thrombus is of particular importance, given the risk of systemic and coronary embolisation. We present a case of a 60-year-old female with an ascending aortic thrombus complicated by non-ST-elevation myocardial infarction (NSTEMI), and associated systemic embolism in the form of renal and splenic infarcts.

Case Report

A 60-year-old female was admitted to a local secondary hospital with a 4-day history of crampy abdominal pain and intermittent bilateral arm pain associated with nausea and vomiting. Past medical history included known hypertrophic cardiomyopathy, gastroesophageal reflux disease, carpal tunnel syndrome, hepatic steatosis, but no known thrombophilia or coronary artery disease. Computer tomography (CT) scan of the abdomen revealed subacute infarction of the right kidney and spleen in keeping with a thrombo-embolic event. A CT pulmonary angiogram revealed a small pulmonary embolus in the right lower lobe. Troponin I level was elevated at 11 mg/L (normal <0.04 mg/L). She was treated with aspirin, clopidogrel and therapeutic enoxaparin for a NSTEMI, and transferred to a metropolitan tertiary centre for ongoing investigation. A transthoracic echocardiogram performed showed known hypertrophic cardiomyopathy, but negative for intracardiac shunting via bubble study. Coronary angiography revealed an acutely occluded distal left anterior descending (LAD) artery with no collaterals, and mild irregularities in all other coronary arteries. A transoesophageal echocardiogram performed to exclude any intracardiac sources of emboli showed a pedunculated and mobile non-calcific mass measuring 1.0cm X 0.5cm in the posterior aspect of the ascending aorta, associated with atheroma in the aortic arch. A laboratory workup for antiphospholipid syndrome, antithrombin III, protein S and protein C deficiency were negative.

After discussion with the multidisciplinary Heart team, the consensus was that the aortic mass was likely thrombus formation relating to erosion of aortic atheroma. It was hypothesised that this may have resulted in distal embolisation to the left kidney and spleen, and possibly also caused embolisation to the LAD artery, although the cause of the pulmonary embolism was still unknown. The patient was then discharged on rivaroxaban and aspirin.

A repeat transoesophageal echocardiogram was performed 4 months after discharge to assess the ascending aortic mass. It showed complete resolution of the mass in the ascending aorta, with no change in any other cardiac structures.

Discussion

Although thrombus formation is uncommon in the ascending aorta, certain conditions, such as pregnancy and thrombophilia increase its risk. Several case reports of ascending aortic thrombus were found in the literature, but this will be the first to report complete resolution with treatment using a direct oral anticoagulant.

Abstract 480 Figure. Ascending Aortic Thrombus + Resolution

Development of a glial cell-derived neurotrophic factor-releasing artificial dura for neural tissue engineering applications

Develop a scaffold consisting of aligned, drug releasing nanofiber to serve as a replacement for damaged dura mater.

Prospective development and validation of a model to predict heart failure hospitalisation

Objective

Acute heart failure syndrome (AHFS) is a major cause of hospitalisation and imparts a substantial burden on patients and healthcare systems. Tools to define risk of AHFS hospitalisation are lacking.

Methods

A prospective cohort study (n=628) of patients with stable chronic heart failure (CHF) secondary to left ventricular systolic dysfunction was used to derive an AHFS prediction model which was then assessed in a prospectively recruited validation cohort (n=462).

Results

Within the derivation cohort, 44 (7%) patients were hospitalised as a result of AHFS during 1 year of follow-up. Predictors of AHFS hospitalisation included furosemide equivalent dose, the presence of type 2 diabetes mellitus, AHFS hospitalisation within the previous year and pulmonary congestion on chest radiograph, all assessed at baseline. A multivariable model containing these four variables exhibited good calibration (Hosmer–Lemeshow p=0.38) and discrimination (C-statistic 0.77; 95% CI 0.71 to 0.84). Using a 2.5% risk cut-off for predicted AHFS, the model defined 38.5% of patients as low risk, with negative predictive value of 99.1%; this low risk cohort exhibited <1% excess all-cause mortality per annum when compared with contemporaneous actuarial data. Within the validation cohort, an identically applied model derived comparable performance parameters (C-statistic 0.81 (95% CI 0.74 to 0.87), Hosmer–Lemeshow p=0.15, negative predictive value 100%).

Conclusions

A prospectively derived and validated model using simply obtained clinical data can identify patients with CHF at low risk of hospitalisation due to AHFS in the year following assessment. This may guide the design of future strategies allocating resources to the management of CHF.

Cell-specific insulin resistance: implications for atherosclerosis

Insulin resistance is increasingly acknowledged as an independent risk factor for cardiovascular disease. Despite this, our understanding of the cellular and molecular mechanisms that might account for this relationship remain incompletely understood. A key challenge has been in distinguishing between a 'whole-body' milieu of inflammation and oxidative stress from the ramifications of cell-specific resistance to insulin. Transgenic models have now begun to explore the cellular influences of insulin resistance on vascular biology, with novel implications for atherosclerosis across a range of cells including endothelial cells, endothelial progenitor cells, vascular smooth muscle cells, macrophages and fibroblasts. Emerging data from these models have also begun to challenge conventional dogma. In particular, the findings across various cell types are disparate with some even implying a protective influence on vascular biology. We now review these data, highlighting recent advances in our understanding of cellular resistance to insulin as well as those areas where there remains a paucity of data.

Is it possible to identify a population in which the incidence of future development of AIS is greatly increased when compared to the normal population?

For future research of predictors of AIS, it would be advantageous to identify a general population in which the development of AIS is greatly increased when compared to the normal population. The probability of predicting future development of AIS among younger relatives of current patients based on the probability of AIS incidence was assessed from the research literature. Although there is considerable literature relating to familial relationships of the probability of developing AIS or having AIS, the probability is relatively low in most cases. Even with the best of predicted probabilities, the identification of patients with a high probability of developing AIS remained low. The identification of people among the general population who have a high probability of developing AIS based on the probabilities expressed in the literature is not possible.

Use of blood donation history of people with HIV infection to identify recipients at risk

OBJECTIVE

To determine whether previous blood donations from HIV-positive patients posed a threat to recipients.

DESIGN

Interviewer-administered questionnaire survey.

SETTING

Regional HIV outpatient referral clinic for southern Alberta.

PATIENTS

All 478 patients attending the clinic from May 1, 1993, to Mar. 31, 1994; 366 were excluded: 335 had not donated blood, and 31 could not provide reliable information regarding possible donations.

INTERVENTIONS

Patients were asked at a routine clinic visit regarding the dates, frequency and location of previous blood donations. The Canadian Red Cross was informed, with patient consent, if the previous donations posed a potential risk of HIV transmission.

OUTCOME MEASURES

Number of HIV-positive patients whose donations posed a possible or definite risk to recipients.

RESULTS

A total of 545 units of blood had been donated by the 112 patients in the study; 57 units (donated by 29 patients) posed a possible risk, and 12 (given by 11 patients) posed a definite risk of HIV transmission to the recipients. Thirty-two of these donors had been unknown to the Red Cross through its "look-back" and "trace-back" protocols. Only 1 of the 13 patients found to be HIV positive by the Red Cross openly admitted donating blood to undergo HIV antibody testing; the remainder were either ill-informed or did not perceive themselves to be at risk. The patients were highly mobile, 36.7% donating blood at some time in a province other than the one where they had received their positive HIV test result.

CONCLUSION

Asking HIV-positive patients about their blood donation history, although subject to recall bias, is a simple and inexpensive method for identifying high-risk blood donations. The Red Cross should routinely be notified, with patient consent, of all donations posing a risk in order to enhance the prospect for identifying HIV-positive blood recipients.