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June 13, 2022

Cardiac computed tomography angiography (CCTA) plays a vital role in clinical practice in evaluating patients with congenital heart disease (CHD) when the information from echocardiography is equivocal.

In this study, researchers from Thailand’s Khon Kaen University set out to test the hypothesis that CCTA has significant value for pre-operative evaluation of CHD and practicality in the diagnosis and management of CHD patients at their tertiary care academic hospital.

Overcoming the limitations of traditional techniques

It was highlighted that cardiologists have traditionally relied on echocardiography and conventional angiography for CHD diagnosis, but that both these techniques have potential limitations. Echocardiography is operator-dependent and limited by an acoustic window, and lung disease further complicates echocardiographic image quality.

Conventional angiography is an invasive procedure with inherent risks and the potential for the confusion of the complex anatomy picture due to overlapping pulmonary and systemic circulations.

Cross-sectional imaging with cardiac magnetic resonance (CMR) or CCTA can overcome these limitations. Both these modalities offer enhanced pre-operative understanding of CHD to simplify surgical decision-making and potentially improve outcomes.

CMR’s disadvantages in developing countries

The study pointed out that CMR can also provide cardiac function and anatomical information which is impossible with echocardiography and invasive angiography alone but poses the disadvantages such as:

  • Requirement of general anesthesia
  • Higher cost
  • Limited availability
  • Image degrading artifacts due to implanted stents and coils

This may make CMR unsuitable for Thailand and other developing countries. CCTA was singled out for its diagnostic performance, offering speedy volume acquisition of the entire heart and coronary arteries, and excellent temporal and spatial resolution. With these benefits in mind, the study set out to accentuate the usefulness of CCTA in assessing congenital cardiovascular diseases across a broad spectrum of pathologic structures.

Patient selection, scanning protocol, and statistical analysis

A total of 78 CHD patients who had undergone CCTA at a tertiary care academic hospital from January 2017 to October 2018 were enrolled. Echocardiography is the first-line modality of choice in all patients with CHD, and CCTA imaging was done only in patients for whom echocardiography or angiography was not a completely informative or mandatory confirmation of echocardiography findings.

Sedation, intubation, and adverse procedural occasions were determined from medical records, and almost all patients could complete CCTA without general anesthesia. Imaging was accomplished using a second-generation dual-source CT scanner (Somatom Definition; Siemens Healthcare, Forchheim, Germany).

In statistical analysis, continuous variables were described as the median and analyses were conducted using version 19.0 of SPSS. Taking the surgical and/or cardiac catheterization results as the standard reference, the sensitivity, specificity, and diagnostic accuracy of CCTA for cardiovascular abnormalities was appraised.

Group classifications

Patients were classified into multiple groups according to several findings for each individual. There were no procedure-related complications. The results were classified as diagnostic categories, and the impact of the procedure on strategizing management was analyzed.

The common indication for CCTA in the study was the requirement to evaluate pulmonary artery anatomy and major aortopulmonary collateral arteries (MAPCAs) in the pulmonary atresia with ventricular septal defect patients. Other than this pulmonary artery evaluation group, other groups included aortic anomalies, coronary artery anomalies, heterotaxy syndrome, and a miscellaneous group.

The advantages of CCTA for a diversity of anatomic abnormalities

The study reported its findings on the specific advantage of CCTA for a diversity of anatomic abnormalities across the spectrum of CHD:

Pulmonary artery evaluation

For the evaluation of pulmonary arteries, CCTA was particularly worthwhile in demonstrating the confluence or discontinuity of the pulmonary MAPCAs, assisting in the selection of surgical techniques, and in evaluating the growth of the pulmonary artery after the procedure.

Aortic anomalies

For aortic anomalies, CCTA precisely identified the coarctation site, the severity of narrowing, and the associated diseases While CCTA in pediatrics is hindered by high heart rate affecting cardiac motion artifacts, in selected cases in the study, this limitation did not preclude demonstration of the origin and course of coronary arteries.

Coronary artery anomalies

CCTA determined the origin and course of the coronary artery precisely in an 8-year-old boy with an anomalous origin of the right coronary artery from the left sinus of Valsalva.

Heterotaxy syndrome

The study found that CCTA was particularly valuable for visceral heterotaxy, establishing the assorted range of abnormalities in various structures in addition to cardiac abnormalities.

Reducing diagnostic invasive catheterization procedures

A previous study had advised that after preliminary valuation with echocardiography, CCTA could possibly substitute invasive diagnostic catheterization for supplementary anatomic clarification in neonates. The researchers believe that this concept could be extended to all age groups for CHD, and reported that after introducing CCTA, the number of diagnostic invasive catheterization procedures decreased dramatically at their institution.

Advantages of CCTA over CMR

While the study acknowledged that CMR does not require ionizing radiation and can provide a range of useful information, it highlighted that CCTA may be preferable to CMR because of its investigation simplicity and image acquisition speed. Other CCTA advantages cited included a shorter scan time and fewer sedation requirements than CMR, making it more suitable for unstable patients. CCTA’s superior ability to identify the coronary arteries and small collateral vessels thanks to its spatial resolution was also reported.

CCTA’s “decision-aiding role” in CHD assessment

In conclusion, the study underlined the superior image quality enabled by advances in CT scanners and CCTA techniques. Dual-source CT scanners were praised as “the foremost innovation in cardiovascular imaging, with superior temporal resolution and the ability to diminish radiation exposure”.

CCTA was shown to have “importance” and a “decision-aiding role” in assessing CHD. The study pointed to its “excellent diagnostic performance, particularly for answering questions not determined by echocardiography”.

Reducing global radiation in CHD patients

It was proposed that “anatomical information attained from CCTA might be prudently used to limit the number of views acquired using invasive catheterization, and it might be a substitute diagnostic method to invasive cardiac catheterization” making it a valuable technique for planning surgery or interventional cardiac catheterization. This, the study suggested, could make CCTA valuable for reducing global radiation exposure in CHD patients.

Sources:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8340641/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8340641/#cit0025