Author + information
- Nitesh Nerlekar, MBBS∗ ( and )
- Arthur Nasis, MBBS, PhD
- ↵∗Monash Heart, Monash Medical Centre, 246 Clayton Road, Clayton 3168, Victoria, Australia
We read with interest the study by Winther et al. (1) who conclude that rather than stress testing, either coronary computed tomographic angiography (CTA) alone or combined with single-photon emission computed tomography (SPECT) should be considered in kidney transplantation candidates. We believe that such a conclusion is premature and warrants consideration of several important issues.
Firstly, coronary CTA is recommended for symptomatic patients at low to intermediate risk of coronary artery disease (CAD) (2). Chronic kidney disease (CKD) patients have a high prevalence of CAD with 37% to 53% having obstructive stenosis on invasive coronary angiography (ICA) (3). The major utility of coronary CTA lies in its ability to exclude obstructive CAD due its high negative predictive value, but has low specificity for detecting obstructive CAD and increases ICA rates compared to a stress testing strategy. In this study, ICA revealed only a 22% incidence of obstructive CAD which may represent a lower risk cohort possibly explained by the low rate of diabetes (33%) which is the most significant predictor of CAD in CKD (4). Furthermore, despite the low CAD prevalence, there was a 29% false positive rate on coronary CTA in part driven by an 18% rate of uninterpretable segments. Therefore, the results of this study may not be generalizable to all potential transplant recipients and may underestimate the false positive rate in higher risk CKD patients.
Secondly, there is no clear association between asymptomatic CAD and prognosis in CKD patients and controversy exists regarding the management of CAD in this population. Screening should only be performed if the result changes management with subsequent improved outcomes. The presence of CAD may result in omission from transplantation listing (5) yet it is unclear whether CAD in CKD impacts survival. Contemporary data suggests no association with reduced survival after observation for up to 4 years (3). There remains equipoise regarding management: if patients are suitable for revascularization, delays to transplantation result from the need for antiplatelet therapy or rehabilitation if surgery is performed. Therefore, if an initial coronary CTA screening strategy is employed, the diagnosis of CAD may result in unnecessary transplantation delay with unintentional harmful effects.
Thirdly, Winther et al. (1) suggest a hybrid approach with coronary CTA and SPECT to improve the low specificity of coronary CTA alone in detecting myocardial ischemia. A drawback of this approach is a high radiation dose, which is not reported in this study. Stress echocardiography provides a radiation-free alternative with superior specificity and more accurate assessment of left ventricular ejection fraction, an independent predictor of survival (3).
Finally, it is not a diagnostic test that influences outcome but its ability to lead to appropriate intervention (medical therapy ± revascularization). Although Winther et al. (1) have shed light on the diagnostic accuracy of coronary CTA in CKD patients, no data is provided regarding any intervention or effect on prognosis of a coronary CTA-guided diagnostic approach. Therefore, we believe it is premature to promote an initial coronary CTA diagnostic strategy until results of future research becomes available that investigates the influence of intervention on coronary CTA findings to improve outcomes.
Please note: Both authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- American College of Cardiology Foundation
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