Role of CT Coronary Angiogram in pre-renal transplant evaluation

Is it good? In 2016, the National Institute for Health and Care Excellence in UK made coronary CTA the first test for all patients without established CAD who present with typical or atypical angina or with non-anginal chest pain plus an abnormal EKG Stress imaging studies were recommended in patients with known CAD Exercise stress ECG testing was not recommended for the diagnosis of CAD due to its low accuracy and high rates of subsequent testing.

CTA has been well tested PROMISE (Prospective Multicenter Imaging Study for Evaluation of Chest Pain; n = 10,003) SCOT-HEART (Scottish Computed Tomography of the Heart; n = 4,146) -At least as effective as strategies that do not utilize coronary CTA for all studied cardiovascular outcomes. -Associated with reduced incident myocardial infarction (MI) in both acute and stable chest pain populations

But… Specificity is not optimal: False-positive with extensive coronary calcifications or high/irregular heart rates. These factors could affect the applicability of coronary CTA in our patient group

Before we poo poo CT imaging….. ……..NO TEST IS PERFECT HERE

Limitations of MPS Altered endothelial function with impaired coronary flow reserve in the absence of epicardial stenosis is well known in diabetic patients with ESRD and could decrease the sensitivity of vasodilator stress testing The presence of severe LVH also could compromise the sensitivity of MPS by missing small and mild perfusion defects due to partial volume effect.

A Cochrane review concluded that the pooled sensitivity was 0 A Cochrane review concluded that the pooled sensitivity was 0.67, with a specificity of 0.77 (95% CI: 0.61 to 0.88), in kidney transplant candidates Wang LW, Fahim MA, Hayen A, et al. Cardiac testing for coronary artery disease in potential kidney transplant recipients. Cochrane Database Syst Rev 2011;(12):CD008691.

Limitations of DSE(dobutamine stress echo) Increased LV mass or concentric remodeling limits the sensitivity for subtle wall motion abnormality. Increased afterload due to hypertensive response could cause transient cavity dilation, flat inotropic response, and WMA in the absence of underlying epicardial CAD.

Limitations of LHC Invasive angiographic evaluations of epicardial stenosis are limited in assessing the functional significance of noncritical coronary stenosis or microvascular function Revascularization improves outcomes only in subset of patients

Is CTA feasible in our population?

If > 1 vessel noninterpretable: scan non-interpretable. 70 patients(ICD2 study): All major epicardial segments were analyzed: 1-3 in RCA; 5-8 in the LAD; 11-13 in LCx If >1 segment in a vessel was non-interpretable: vessel non-interpretable. If > 1 vessel noninterpretable: scan non-interpretable. -this is the ICD study -dialysis patients have calcification in media as well

Total 627 segments analyzed, 91.4% were considered interpretable Patients with non-interpretable segments had higher BMI (29.8 vs. 25.4 kg/m2). No other significant differences between patients with and without non-interpretable segments. In particular, were no significant differences with regard to heart rate during scanning and CACS.

Significant lesion was found in 15.3% segments, 42.9% patients Incidence of cardiovascular events after 2-years follow-up: -36% in patients with significant CAD on CT -None in patients with no significant CAD on CT

9 hospitals in Denmark, 2011- 2014. Inclusion criteria: CKD and presence of at least 1 of the following characteristics: Age >40 years, diabetes, dialysis treatment for >5 years, registered on kidney transplant waiting list for >3 years without cardiac screening, symptoms of cardiovascular disease All patients were scheduled for 1) CACS and coronary CTA; 2) stress SPECT; and 3) ICA.

68 patients (49%) had an abnormal coronary CTA scan. 2 patients were misclassified as normal according to coronary CTA despite obstructive CAD on ICA. Stenosis in these 2 patients were located in the distal RCA and in the second diagonal branch

Results CTA: Sensitivity, specificity, PPV, and NPV for obstructive CAD were 93% , 63%, 41% , and 97%. -The sensitivity for obstructive CAD in a proximal segment was 100% SPECT: Sensitivity, specificity, PPV, and NPV were 53%, 82%, 44% and 86% . -Compared with coronary CTA, the sensitivity was lower (p < 0.01) and specificity was higher (p < 0.01)

Hybrid imaging? Hybrid (coronary CTA/ SPECT) classified as normal regardless of the SPECT result when coronary CTA is normal because of the very high NPV of coronary CTA. Classified as abnormal regardless of the SPECT result when the coronary CTA displayed 3-vessel or left main disease because of the risk of “balance ischemic” vessel disease, a situation in which the SPECT result is false negative due to the flow reserve of each of the coronary arteries being equally impaired.

Hybrid reduced the sensitivity and increased the specificity compared with coronary CTA alone, and the PPV increased from 41% for coronary CTA to 57% for the Hybrid (coronary CTA/SPECT). It outperformed SPECT on all diagnostic variables.

Coronary CTA had a significantly higher sensitivity and NPV for diagnosing obstructive CAD but a lower specificity than CACS(>400) and MPS Hybrid imaging with coronary CTA and MPS had a moderate sensitivity and a high specificity compared with MPS or coronary CTA alone.

31 patients with advanced CKD/ESRD The median CACS was 519, and the prevalence of ICA-verified obstructive CAD was high (61%). Coronary CTA had a sensitivity and specificity of 100% and 91%, respectively. Jug B, Kadakia J, Gupta M, et al. Coronary calcifications and plaque characteristics in patients with end-stage renal disease: a computed tomographic study. Coron Artery Dis 2013;24:501–8.

Perhaps…. In view of the known excellent negative predictive value of a CACS of 0 and normal CTA results in excluding significant angiographic CAD, the potential role of CTA likely rests in serving as gatekeeper for invasive angiography in those patients with submaximal, equivocal, or mildly abnormal stress testing results.

Any role for CACS alone?

Future direction?

https://www. youtube. com/watch https://www.youtube.com/watch?v=_TRuHtpHRuA&list=PLRtOTHEegkp9yFjNVMijgjNFBl6UXmbsI