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Early outcomes following integration of computed tomography (CT) coronary angiography service in an established cardiology practice in disease management
Advara HeartCare, 3/245 Given Terrace, Paddington, QLD, 4064, AustraliaSchool of Medicine, The University of Notre Dame Australia, Fremantle, WA, Australia
Advara HeartCare, 3/245 Given Terrace, Paddington, QLD, 4064, AustraliaDepartment of Cardiology, Austin Health, Melbourne, VIC, AustraliaDepartment of Medicine, The University of Melbourne, Melbourne, VIC, Australia
Computed tomography coronary angiography (CTCA) is an established modality for the diagnosis and assessment of cardiovascular disease. However, price and space pressure have mostly necessitated outsourcing CTCA to external radiology providers. Advara HeartCare has recently integrated CT services within local clinical networks across Australia. This study examined the benefits of the presence (integrated) or absence (pre-integrated) of this “in-house” CTCA service in real-world clinical practice.
Methods
De-identified patient data from electronic medical records were used to create an Advara HeartCare CTCA database. Data analysis included clinical history, demographics, CTCA procedure, and 30-day outcomes post-CTCA from two age-matched cohorts: integrated (n = 495) and pre-integrated (n = 456).
Results
Data capture was more comprehensive and standardised across the integrated cohort. There was a 21% increase in referrals for CTCA from cardiologists observed for the integration cohort vs. pre-integration [n = 332 (72.8%) pre-integration vs. n = 465 (93.9%) post-integration, p < 0.0001] with a parallel increase in diagnostic assessments including blood tests [n = 209 (45.8%) vs. n = 387 (78.1%), respectively, p < 0.0001]. The integrated cohort received lower total dose length product [Median 212 (interquartile range 136–418) mGy∗cm vs. 244 (141.5, 339.3) mGy∗cm, p = 0.004] during the CTCA procedure. 30-days after CTCA scan, there was a significantly higher use of lipid-lowering therapies in the integrated cohort [n = 133 (50.5%) vs. n = 179 (60.6%), p = 0.04], along with a significant decrease in the number of stress echocardiograms performed [n = 14 (10.6%) vs. n = 5 (11.6%), p = 0.01].
Conclusion
Integrated CTCA has salient benefits in patient management, including increased pathology tests, statin usage, and decreased post-CTCA stress echocardiography utilisation. Our ongoing work will examine the effect of integration on cardiovascular outcomes.
A normal study (zero calcium, no visible atherosclerosis) is associated with very low long-term cardiovascular event rates and may help reclassify intermediate-risk patients to low-risk.
The use of CTCA in addition to standard of care in patients with stable chest pain assists with clinical decision-making, with subsequent treatment decisions resulting in a lower rate of death from non-fatal myocardial infarction or coronary heart disease two months after diagnosis.
Low-attenuation noncalcified plaque on coronary computed tomography angiography predicts myocardial infarction: results from the multicenter SCOT-HEART trial (Scottish Computed Tomography of the HEART).
CT coronary angiography in patients with suspected angina due to coronary heart disease (SCOT-HEART): an open-label, parallel-group, multicentre trial.
Identification of patients with stable chest pain deriving minimal value from coronary computed tomography angiography: an external validation of the PROMISE minimal-risk tool.
Rationale and design of the coronary computed tomographic angiography for selective cardiac catheterization: relation to cardiovascular outcomes, cost effectiveness and quality of life (CONSERVE) trial.
Calcium imaging and selective computed tomography angiography in comparison to functional testing for suspected coronary artery disease: the multicentre, randomized CRESCENT trial.
have demonstrated CTCA is an important first step in evaluating patient chest pain. This has led the Australian cardiac health advisory, Cardiac Society of Australia and New Zealand (CSANZ), to outline the use of CTCA in the guidelines for non-invasive coronary artery imaging.
Identification of patients with stable chest pain deriving minimal value from coronary computed tomography angiography: an external validation of the PROMISE minimal-risk tool.
Rationale and design of the coronary computed tomographic angiography for selective cardiac catheterization: relation to cardiovascular outcomes, cost effectiveness and quality of life (CONSERVE) trial.
As a direct result of this, many Australian health insurers updated their reimbursement policies to cover CTCA as a “first line” test to assess stable chest pain in patients with low or intermediate risk for coronary artery disease (CAD).
This guideline is in alignment with UK's National Institute for Health and Care Excellence (NICE) and European Society of Cardiology (ESC) guidelines recommendation for CTCA as the first test for stable chest pain in 2016 and 2019, respectively.
Despite these endorsements from professional societies, CTCA is typically outsourced to an external (often geographically close) service provider, often due to multiple perceived issues of cost, referral volume, service capacity and floor space. However, since most other tools used for cardiovascular risk prediction are co-located in cardiology services, such as echocardiography, stress echocardiography and electrocardiography, with competency in cardiac CT interpretation amongst cardiologists has become more frequent, there have been increasing calls for integration of CTCA service as well. The potential clinical impact of integrated CTCA services has not been explored. We recently integrated cardiac CT scanners at 4 cardiology practices across Australia (Queensland, Western Australia, South Australia, and Victoria), and retrospectively studied the clinical impact of integration of CTCA compared with pre-integration (involving external CTCA referral to radiology practices).
2. Methods
2.1 Study design and population
The integrated CT scanners were a GE Cardiographe™ [GE Healthcare, NSW; installed in Perth (Western Australia), Melbourne (Victoria), and Brisbane (Queensland) in February 2020, October 2020, and February 2021, respectively] and a Siemens Cardiac CT machine [Siemens Healthcare, Vic; installed in Adelaide (South Australia) in November 2019]. The pre-integration CT scanners consisted of GE Cardiographe™ (Queensland and Victoria), GE Revolution™ (Victoria and Western Australia), Siemens Cardiac CT machine (South Australia), Toshiba Aquilion ONE (Queensland, Victoria, and Western Australia), Canon Aquilion (Western Australia), and Phillips ICT (Queensland and Western Australia). At all sites, CTCA was performed as per standard imaging protocol
with a skilled CT radiographer, and images were stored in an analysis workstation (GE or Siemens) for subsequent analysis and 3D reconstruction, and a Picture Archive Cardiology System (PACS) for storage and co-reporting with a radiologist. All reporting was performed by either a cardiologist and radiographer with training and accreditation in CTCA, who selected the best imaging procedure for the patient. Pre-integrated services had limited cardiologists’ input whereas patients in the integrated service were reviewed by a cardiologist to ensure safety, including heart rate regulation (with oral and/or intravenous beta-blockers, and oral ivabradine) and short-acting sublingual nitrates.
A retrospective CTCA database was developed involving all four CTCA sites. All individuals in this study are outpatients being evaluated for stable coronary disease. Data was collected based on available data from existing Advara HeartCare Cardiac Outcome Registry (AHCOR) information and supplemented with contemporaneous CTCA report data obtained from Advara HeartCare electronic health records (EMR). All patients with CTCA data available were extracted from the EMR and divided into two cohorts: integrated and pre-integrated, depending on whether the patient had a CTCA prior to integration (at an external radiology service reported by a radiologist), or following the integration of cardiac CT scanner (within the cardiology service reported by a cardiologist). Pre-integrated patients received their scans between February 21, 2016 to April 13, 2021 and the integrated scans between November 18, 2019 and September 22, 2021. The two cohorts of patient data were matched for sex and age at the time of CTCA procedure, providing 500 patients in each group. The study complied with the Declaration of Helsinki and was approved by the Bellberry Human Research Ethics Committee (ID#2020-03-234).
2.2 Data collection
All relevant data were collected in a de-identified database and included standard clinical and pathology assessments collected at both baseline and 30-day follow-up. Additionally, reports including CT procedural reports and clinical follow-up information was also reviewed and collected to provide a dataset with structured information.
Coronary artery calcium (CAC) was measured at low-dose (<1 mSv), and electrocardiogram-gated with no contrast and reported as Agatston/Janowitz −130 (AJ-130) units according to the area and density of coronary calcium lesions,
and recorded as an absolute score (unitless). Multi-Ethnic Study of Atherosclerosis (MESA) risk scores were calculated using baseline data on race, gender and age along with the recorded CAC score (CACS). Patients with coronary stents, pacing leads, or extensive non-coronary cardiac calcification did not have a CACS calculated. Patients with no ethnicity listed were assumed to be of “non-Hispanic white” race as they are the largest pan-ethnic cohort in Australia.
The presence and extent of Coronary Artery Disease–Reporting and Data System (CAD-RADS) scores were calculated by following Cury et al.‘s (2016) guidelines.
CAD-RADS(TM) coronary artery disease - reporting and data system. An expert consensus document of the society of cardiovascular computed tomography (SCCT), the American college of radiology (ACR) and the North American society for cardiovascular imaging (NASCI). Endorsed by the American college of cardiology.
In addition, dyslipidaemia [total cholesterol (mmol/L), HDL cholesterol (mmol/L)], systolic blood pressure (mmHg), presence or absence of hypertension medication, lipid-lowering therapy, diabetes, family history of myocardial infarction and smoking status were recorded. Patients with no documentation on any of binary/categorical variables required for calculating risk scores were considered as “absent” for the specific risk factor and given an appropriate score.
2.3 Statistical analysis
Categorical variables were reported as numbers with percentages and compared using the Chi-squared test or Fisher's exact test. Continuous variables were reported as mean [±standard deviation (S.D)] if normally distributed, or median with interquartile ranges (IQR) for non-normally distributed data, with comparisons performed using Student's t-test or Mann–Whitney U test respectively. Significant differences were identified using two-sided p-values of <0.05. Statistical analysis was performed using GraphPad Prism version 8.0.0 (GraphPad Software INC., San Diego, California USA) and IBM SPSS Statistics version 27.0 (SPSS Software INC., Chicago, Illinois, USA) for Windows.
3. Results
3.1 Study cohort
Of the 1000 patients, final data analysis was performed on a total of 951 patients (n = 495 integration cohort vs. n = 456 pre-integration cohort). 49 patients were excluded due to incomplete data in the CTCA procedure. Patient baseline characteristics are presented in Table 1. In both cohorts, cardiovascular risk factors were common including dyslipidaemia [n = 278 (60.9%) pre-integration vs. n = 282 (56.7%) integration, p = ns], diabetes [n = 52 (11.4%) vs. 60 (12.1%), p = ns], hypertension [n = 210 (46.0%) vs. n = 203, (41.0%), p = ns], and a family history of CAD [n = 135, (29.6%), vs. n = 180, (36.4%), p = ns]. In the integration cohort, renal function testing prior to CTCA increased significantly [n = 209 (42.2%) vs. n = 387, (84.9%) p < 0.0001, Fig. 1A], with a smaller number of individuals being started on anti-platelet medication prior to their CTCA [n = 135 (29.6%) vs. n = 98 (19.7%), p = 0.0007, Fig. 1B].
Fig. 1Baseline Pathology tests and Medications. Pre-integration (black) and Integration (grey) cohorts baseline (A) serum creatinine and (B) medications. Anti-platelets included aspirin, clopidogrel, and ticagrelor. Anti-coagulants included warfarin, dabigatran, rivaroxaban and apixaban. RAASi included ACEi, ARB, and ARNI. Statistical comparisons were performed between corresponding populations by Mann-Whitney test. P-values not shown are not significant. ACEi = Angiotensin-Converting Enzyme Inhibitors; ARBs = Angiotensin Receptor Blockers; ARNI = Angiotensin Receptor Neprilysin Inhibitors; BB = Beta-Blockers, RAASi = Renin-angiotensin-aldosterone system inhibitors.
CT procedural characteristics were collected to highlight any differences in the workflow (Table 2). All patients (100%) had a CTCA, with simultaneous CAC more likely after integration. Cardiologists were significantly more likely to refer for CTCA with an integrated service [n = 332 (72.8%) pre-integration vs. n = 465 (93.9%) integration, p < 0.0001]. Patients post-integration tended to be higher risk such as being treated with diabetes medications and relative contraindications [n = 44 (9.6%) vs. n = 100 (20.2%), p = 0.04]. Nitrates were given more commonly and at a higher median dose [median 600mcg (interquartile range 400–800) vs. 800mcg (400–800), p < 0.0001], whereas the median bradycardia-inducing medications were similar in both cohorts. The integrated cohort had a lower total dose length product [DLP; 244 mGy-cm (141.5, 339.3) vs. 212 mGy-cm (136, 418), p = 0.004].
Cardiac Risk stratification includes patients with family history of CAD/MI, negative stress echo, obstructive coronary artery disease, and premature CAD.
Cardiac Risk stratification includes patients with family history of CAD/MI, negative stress echo, obstructive coronary artery disease, and premature CAD.
Cardiac Risk stratification includes patients with family history of CAD/MI, negative stress echo, obstructive coronary artery disease, and premature CAD.
57 (12.5%)
70 (14.1%)
ns
Patient Characteristics at Procedure
Pre-scan Electrocardiogram (ECG)
129 (28.2%)
326 (65.8%)
p < 0.0001
Relative Contraindications for CT scan
44 (9.6%)
100 (20.2%)
p = 0.04
Asthma
3 (0.6%)
18 (3.6%)
ns
Diabetes/metformin/gliclazide
19 (4.1%)
41 (8.2%)
ns
Allergies
2 (0.4%)
16 (3.2%)
ns
Other
25 (5.5%)
31 (6.3%)
ns
Procedure-related characteristics
Glyceryl Trinitrate (GTN)
327 (71.7%)
486 (98.1%)
p < 0.0001
GTN dose (mcg), median (IQR)
600 (400, 800)
800 (400, 800)
p < 0.0001
Metoprolol
225 (49.3%)
271 (54.7%)
ns
Metoprolol dose (mg), median (IQR)
50 (50, 100)
50 (50,100)
p = 0.04
Ivabradine
36 (7.8%)
58 (11.7%)
ns
Ivabradine dose (mg), median (IQR)
10 (10,15)
7.5 (7.5, 12.5)
p = 0.002
Total contrast volume documented
Contrast volume documented
131 (28.7%)
446 (90.1%)
p < 0.0001
Contrast volume (IV), mL
80.7 ± 27.3
81.2 ± 20.0
ns
CT scan type
GE
10 (2.1%)
340 (68.6%)
ns
Siemens
128 (28%)
19 (3.8%)
ns
Other
44 (9.6%)
0 (0%)
ns
Unknown
258 (56.5%)
134 (27%)
ns
Total dose-length product (DLP), mGy-cm, median (IQR)
244 (141.5, 339.3)
212 (136, 418)
p = 0.004
Documentation of Image Quality
Excellent
121 (24.2%)
71 (14.2%)
p < 0.0001
Good
93 (18.6%)
227 (45.4%)
p < 0.0001
Fair
18 (3.6%)
56 (11.2%)
p < 0.0001
Non-diagnostic
0 (0%)
2 (0.4%)
p < 0.0001
Not documented
268 (53.6%)
144 (28.8%)
p < 0.0001
CTCA/CAC score by vessel (AJ-130)
Total coronary artery calcium score (HU), mean ± SD
218.3 ± 525.9
184.8 ± 471.3
ns
Calcium score percentile, mean ± SD
44.3 ± 37.1
45.3 ± 35.2
ns
Distribution dominance
406 (89%)
485 (97.9%)
ns
Co-dominant system
7 (1.5%)
26 (5.2%)
ns
Left dominant system
30 (6.5%)
61 (12.3%)
p = 0.006
Right dominant system
369 (80.9%)
398 (80.4%)
ns
CAD-RADS score from One site
61 (13.3%)
69 (13.9%)
ns
Additional Calculated Risk Score
Assumptive MESA score calculated for:
93 (20.4%)
179 (36.1%)
ns
MESA-10-year risk, mean ± SD%
7.5 ± 5.3%
6.8 ± 5.2%
ns
MESA-10- year risk with CAC, mean ± SD%
11.6 ± 7.2%
9.9 ± 8.4%
ns
CAC = 0–0.9
182 (39.9%)
169 (34.1%)
ns
CAC = 1–100
99 (21.7%)
139 (28.1%)
ns
CAC = ≥ 100
123 (26.9%)
126 (25.4%)
ns
Statistical comparisons were performed between corresponding populations by Mann-Whitney test. P-values not shown are not significant.
BB = Beta Blocker; CAC = Coronary Artery Calcification; CAD = Coronary Artery Disease; CT = Computed Tomography; CTCA = CT Coronary Angiography; RAD = Reporting and Data System; SD = Standard Deviation; MESA = Multi-Ethnic Study of Atherosclerosis; MI = Myocardial Infarction.
a Cardiac Risk stratification includes patients with family history of CAD/MI, negative stress echo, obstructive coronary artery disease, and premature CAD.
b Other = additional free text data collected on patients who did not fit the multiple choices provided during data entry for that variable.
The integrated cohort had higher documentation of CT procedures details such as contrast volume [n = 131 (28.7%) pre-integration vs. n = 446 (90.1%) post-integration, p < 0.0001] and data on image quality [n = 232 (46.4) vs. n = 356 (71.2%) p < 0.0001]. No differences were observed between the cohorts for total CAC, CAD-RADS or MESA risk scores.
3.3 30-Day outcomes
Data on 30-day outcomes (Table 3) was collected for n = 558 (58.7%) of all patients at baseline. Patients lost to 30-day follow-up included: 53 patients (5.6% of baseline cohort) discharged before 30-day follow-up period, 128 patients (13.5% of baseline cohort) had a follow-up outside of the 30-day timeframe and 27 patients (2.8% of baseline cohort) were lost to follow-up, while 185 patients (19.4% of baseline cohort) had missing data. Of the remaining patients, we observed no mortality events at 30 days, and no differences in hospitalisation between cohorts. Post-CT stress echocardiography was almost three times lower in the integrated cohort [n = 31 pre-integrated (11.7%) vs. n = 12 integrated (4.0%), p = 0.01]. In parallel with “normal” reports, anti-platelet use was lower [n = 104 (39.5%) vs. n = 90 (30.5%), p = 0.008] whereas with higher atherosclerosis disease burden, cholesterol-lowering medication use increased [n = 133 (50.5%) vs. n = 179 (60.6%), p = 0.04] in the integrated cohort (Table 3). Minor differences in recommendations for lifestyle modifications did not meet statistical significance.
Table 330-Day outcomes.
n (%)
Pre-integration
Integrated
p-value
Patient Data Available at 30 days
263 (100%)
295 (100%)
Number of Patients Alive at 30 days
263 (100%)
295 (100%)
Lost to follow up
14 (5.3%)
13 (4.4%)
ns
Death
0 (0%)
0 (0%)
ns
Hospitalisations
33 (12.5%)
34 (11.5%)
ns
Reason for Hospitalisation(s)
Arrhythmia
1 (0.4%)
4 (1.3%)
ns
Coronary Angiogram - Planned
19 (7.2%)
17 (5.7%)
ns
PCI Planned
2 (0.8%)
3 (1.0%)
ns
PCI Unplanned
2 (0.8%)
3 (1.0%)
ns
Non-cardiac chest pain
1 (0.4%)
2 (0.7%)
ns
CABG
1 (0.4%)
2 (0.7%)
ns
Other
7 (2.7%)
3 (1.0%)
ns
Average Length of hospital stay (LOS) ± SD
1.2 ± 0.5
1.6 ± 1.9
Patients with LOS = 1 day
21 (7.9%)
24 (8%)
ns
Patients with LOS = 2 days
5 (2%)
4 (1.3%)
ns
Patients with LOS ≥2 days
4 (1.5%)
3 (1%)
ns
Documented Pathology Tests
Serum Creatinine
36 (13.6%)
48 (16.2%)
ns
Haemoglobin A1c
12 (4.5%)
20 (6.7%)
ns
Fasting Glucose
12 (4.5%)
20 (6.7%)
ns
Documented Metabolic Tests
27 (10.2%)
47 (15.9%)
p = 0.07
Total Cholesterol, mmol/L, mean ± SD
4.7 ± 0.9
4.4 ± 1.1
ns
LDL-C, mmol/L, mean ± SD
2.6 ± 0.8
2.5 ± 0.9
ns
HDL-C, mmol/L, mean ± SD
1.5 ± 0.6
1.4 ± 0.5
ns
Triglyceride, mmol/L, mean ± SD
1.8 ± 1.4
1.4 ± 0.6
ns
Medications
Anti-platelets
104 (39.5%)
90 (30.5%)
p = 0.008
Anti-coagulants
30 (11.4%)
36 (12.2%)
ns
BB
68 (25.8%)
65 (22%)
ns
RAASi
96 (36.5%)
110 (37.3%)
ns
Nitrates
15 (5.7%)
6 (2%)
ns
Nicorandil
2 (0.7%)
2 (0.6%)
ns
Ezetimibe
15 (5.7%)
21 (7.1%)
ns
Statins
133 (50.5%)
179 (60.6%)
p = 0.04
Post-CT diagnostic tests
114 (43.3%)
94 (31.8%)
p = 0.007
Echocardiogram
26 (9.8%)
16 (5.4%)
Stress echocardiogram
31 (11.7%)
12 (4.0%)
p = 0.01
Coronary angiography
24 (9.1%)
23 (7.7%)
ns
Other
43 (16.3%)
53 (18.0%)
ns
Documented post-CT lifestyle modifications
33 (12.5%)
66 (22.3%)
ns
Diet
16 (6.1%)
29 (9.8%)
ns
Exercise
11 (4.1%)
32 (10.8%)
ns
Reduce alcohol consumption
1 (0.3%)
4 (1.3%)
ns
Recommendation to quit smoking
10 (3.8%)
5 (1.6%)
ns
Maintain Healthy Weight/BMI
4 (1.5%)
20 (6.7%)
ns
Other
11 (4.1%)
19 (6.4%)
ns
Statistical comparisons were performed between corresponding populations by Mann-Whitney test. P-values not shown are not significant.
A more granular investigation of patient calcium scores (CACS 0, CACS 1–100, and CACS >100) on patient downstream testing at 30-day is shown in Table 4 and Supplementary Table 1. The integrated group had a higher proportion of patients with CACS 0 who made dietary changes [n = 3 (3%) pre-integrated vs. n = 10 (11.6%) integrated, p = 0.02] and maintained a healthy weight/BMI [n = 1 (1%) vs. 8 (9.3%), respectively, p = 0.01]. Post-CTCA stress echocardiogram testing in the integrated cohort was significantly lower in both the CACS 1–100 and CACS >100 groups when compared to the pre-integrated cohort [CACS 0: n = 8 (15.1%) vs. n = 3 (3.5%), p = 0.02 and CACS >100, n = 14 (17.1%) vs. n = 5 (5.6%), p = 0.03]. A greater number of integrated patients with CACS >100 was on cholesterol-lowering statins, compared to the pre-integrated cohort [n = 63 (76.8%) vs. n = 81 (91%), p = 0.01]. Despite this significant statin change, we found no significant difference in medication gain per patient between the CACS groups (Supplementary Table 1), however this may be due to small sample size.
Table 430-day patient diagnostic assessment and outcomes as stratified to CAC scores.
To our knowledge, this is the first study to examine the potential benefits of integration of a cardiac CT facility within a clinical cardiology practice, allowing a more streamlined service and potentially optimising CAD management. We have demonstrated improved clinical patient management in four key areas
; improved risk factor modification (in particular, prescription of lipid lowing therapy and antiplatelet therapy) when atherosclerosis was demonstrated on CTCA
; a decrease in requests for stress echocardiography after CTCA. Our objective demonstrates that integrated coronary imaging improves key measures of clinical management and future planning of cardiology services in cardiac patients.
Previous studies have revealed that implementing medical technologies into clinical practices improves the quality of care and increases clinical diagnostic assessments.
We have extended these observations with a decrease in post-CTCA diagnostics tests, such as stress echocardiography with important cost implications and a shortening of time to final diagnosis. Our results are consistent with the findings from PROMISE, in which CTCA may be interpreted as an alternative to stress echocardiography.
in which the CTCA arm was associated with more intense medical therapy and favourable cardiovascular outcomes at 5 years. Although stress echocardiography vs CTCA should not be seen as a binary choice,
stress echocardiography is most suitable for evaluation of ischaemia and a normal result does not exclude the presence of coronary artery disease. As such, CTCA may be seen as a more suitable test to assist in treatment decisions around lipid-lowering therapy
Prognostic value of coronary artery calcium score, area, and density among individuals on statin therapy vs. non-users: the coronary artery calcium consortium.
and should be performed prior to stress echocardiography when clinically appropriate. Our observation of lower stress echocardiography usage after CTCA integration highlights this change in workflow, noting that stress echocardiography remained relevant for a subgroup of patients after CTCA was performed. These were predominantly those with CACS>400 and those with moderate (50–69%) obstructive disease noted on CTCA, where the likelihood of coronary ischaemia was unclear based on CTCA alone. This is consistent with studies showing the complementary value of stress echocardiography in intermediate CTCA results.
and use of antiplatelet therapy, improving this decision process has direct clinical relevance. There is evidence in favour of CT-guided decisions around lipid-lowering therapy
compared with the absence of CACS information, and changes in risk factor modification therapies post-CTCA diagnosis significantly reduce patient death from myocardial infarction or CAD.
Our finding that 30-days post-CT the integration cohort had a higher proportion of lipid-lowering therapy suggests improved imaging-guided management decisions. At baseline and 30-day post-CTCA, anti-platelet medications usage was significantly lower in the integration cohort suggesting that patients having a CTCA externally may have had delayed decisions on antiplatelet therapy or that a decision to stop antiplatelet therapy was made based on a normal CTCA result.
Our finding revealed a tendency of improved adherence to lifestyle recommendations is consistent with other studies where physician-patient interaction, and visualisation of their coronary artery images influenced individual patient behaviour.
CT coronary angiography in patients with suspected angina due to coronary heart disease (SCOT-HEART): an open-label, parallel-group, multicentre trial.
trials demonstrated that patients with detected CAD through CTCA were more likely to receive appropriate preventive therapies, and consequently, may have greater motivation to implement healthy lifestyle modifications, although we did not prospectively examine the potential beneficial effects of lifestyle modification.
The integration cohort received a lower radiation dose length product (DLP) than previous effective dose studies such as the Prospective Randomized Trial on Radiation Dose Estimates of Cardiac CT Angiography in Patients Scanned with a High-Pitch Helical Scan Strategy (PROTECTION VI)
Current worldwide nuclear cardiology practices and radiation exposure: results from the 65 country IAEA Nuclear Cardiology Protocols Cross-Sectional Study (INCAPS).
Conversely, the radiation dose from the pre-integration cohort compares well to the total DLP interquartile range of 246 (153–402) seen in the PROTECTION VI study.
While higher image quality was reported in the integrated cohort, we were unable to directly compare heart rates because of a lack of documentation in the pre-integration cohort.
In Australia, doctors in various specialities such as cardiology, nuclear medicine and radiology, are required to undergo a comprehensive training program to be accredited to report CTCA imaging scans.
Conversely, in several European and North American countries, only radiologists can endorse CTCA diagnostic reports, irrespective of the level of cardiologist proficiency in CTCA imaging.
SCCT guideline for training cardiology and radiology trainees as independent practitioners (level II) and advanced practitioners (level III) in cardiovascular computed tomography: a statement from the society of cardiovascular computed tomography.
While the present study did not concentrate on the professions of those who conducted the diagnostic report, all patients within the integrated CTCA service had their report finalised by a cardiologist, while pre-integrated services had limited cardiologists' input. This more intense point-of-contact with cardiologists could explain the improvements in workflow and documentation. Although the ability of cardiologists to authorise the final diagnostic report may vary by jurisdiction, other countries may consider offering specialised cardiac CT education programmes for general cardiologists as part of their training.
This initiative will enhance cardiologists' ability to refer suitably and comprehend the CTCA reports they receive, which would increase the modality's efficiency.
4.1 Limitations
Our study has some important limitations. Due to its retrospective nature, the study is not randomized, and other external factors may have influenced the result. In addition, missing data due to lack of documentation (particularly in the pre-integration group) could have potentially influenced the results. Although we were unable to capture complete data on 41.3% of patients at 30 days post-CTCA, many of these patients were discharged prior to 30 days due to lack of significant coronary artery disease, highlighting the efficiency of an early CTCA approach to evaluation of patients with suspected CAD. It is important to note that this study was not intended to detect differences in clinical outcomes (such as death or myocardial infarction). Finally, the cost-effectiveness of an integrated CT service compared with a non-integrated service has not yet been investigated.
5. Conclusion
Integration of CTCA service into cardiology clinics was associated with potential benefits to patient care through improved pre-procedure pathology testing, revised use of lipid-lowering, and antiplatelet therapy based on imaging results, and a reduction in the use of post-CTCA stress echocardiography. The integration cohort also had lower radiation dosages. Each of these has important implications for individual patient management and suggests a potentially greater role for integrated non-invasive coronary imaging within cardiology practice in the future. Our future work involves the evaluation of long-term outcomes of an integrated approach and evaluation of cost-effectiveness.
Formatting of funding sources
This study was supported by GE Healthcare Australia Pty Ltd.
Declaration of competing interest
Amied Shadmaan and Daneh Turner are employees of GE Healthcare. The remaining authors have no relevant disclosures.
Acknowledgements
We wish to acknowledge the Clinical Data team at Advara HeartCare, who gathered the data for the CTCA registry.
Appendix A. Supplementary data
The following is the Supplementary data to this article:
Low-attenuation noncalcified plaque on coronary computed tomography angiography predicts myocardial infarction: results from the multicenter SCOT-HEART trial (Scottish Computed Tomography of the HEART).
CT coronary angiography in patients with suspected angina due to coronary heart disease (SCOT-HEART): an open-label, parallel-group, multicentre trial.
Identification of patients with stable chest pain deriving minimal value from coronary computed tomography angiography: an external validation of the PROMISE minimal-risk tool.
Rationale and design of the coronary computed tomographic angiography for selective cardiac catheterization: relation to cardiovascular outcomes, cost effectiveness and quality of life (CONSERVE) trial.
Calcium imaging and selective computed tomography angiography in comparison to functional testing for suspected coronary artery disease: the multicentre, randomized CRESCENT trial.
CAD-RADS(TM) coronary artery disease - reporting and data system. An expert consensus document of the society of cardiovascular computed tomography (SCCT), the American college of radiology (ACR) and the North American society for cardiovascular imaging (NASCI). Endorsed by the American college of cardiology.
Prognostic value of coronary artery calcium score, area, and density among individuals on statin therapy vs. non-users: the coronary artery calcium consortium.
Current worldwide nuclear cardiology practices and radiation exposure: results from the 65 country IAEA Nuclear Cardiology Protocols Cross-Sectional Study (INCAPS).
SCCT guideline for training cardiology and radiology trainees as independent practitioners (level II) and advanced practitioners (level III) in cardiovascular computed tomography: a statement from the society of cardiovascular computed tomography.
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