Optimal diagnostic approach for using CT-derived quantitative flow ratio in patients with stenosis on coronary computed tomography angiography.

BACKGROUND: Coronary computed tomography angiography (CCTA)-derived quantitative flow ratio (CT-QFR) is an on-site non-invasive technique estimating invasive fractional flow reserve (FFR). This study assesses the diagnostic performance of using most distal CT-QFR versus lesion-specific CT-QFR approach for identifying hemodynamically obstructive coronary artery disease (CAD). METHODS: Prospectively enrolled de novo chest pain patients (n â€‹= â€‹445) with ≥50 â€‹% visual diameter stenosis on CCTA were referred for invasive evaluation. On-site CT-QFR was analyzed post-hoc blinded to angiographic data and obtained as both most distal (MD-QFR) and lesion-specific CT-QFR (LS-QFR). Abnormal CT-QFR was defined as ≤0.80. Hemodynamically obstructive CAD was defined as invasive FFR ≤0.80 or ≥70 â€‹% diameter stenosis by 3D-quantitative coronary angiography. RESULTS: In total 404/445 patients had paired CT-QFR and invasive analyses of whom 149/404 (37 â€‹%) had hemodynamically obstructive CAD. MD-QFR and LS-QFR classified 188 (47 â€‹%) and 165 (41 â€‹%) patients as abnormal, respectively. Areas under the receiver-operating characteristic curve for MD-QFR was 0.83 vs. 0.85 for LS-QFR, p â€‹= â€‹0.01. Sensitivities for MD-QFR and LS-QFR were 80 â€‹% (95%CI: 73-86) vs. 77 â€‹% (95%CI: 69-83), p â€‹= â€‹0.03, respectively, and specificities were 73 â€‹% (95%CI: 67-78) vs. 80 â€‹% (95%CI: 75-85), p â€‹< â€‹0.01, respectively. Positive predictive values for MD-QFR and LS-QFR were 63 â€‹% vs. 69 â€‹%, p â€‹< â€‹0.01, respectively, and negative predictive values for MD-QFR and LS-QFR were 86 â€‹% vs. 85 â€‹%, p â€‹= â€‹0.39, respectively). CONCLUSION: Using a lesion-specific CT-QFR approach has superior discrimination of hemodynamically obstructive CAD compared to a most distal CT-QFR approach. CT-QFR identified most cases of hemodynamically obstructive CAD while a normal CT-QFR excluded hemodynamically obstructive CAD in the majority of patients.

The Diagnostic Yield and Clinical Impact of Systematic Screening of Kidney Transplant Candidates by Cardiac Computed Tomography: A Cohort Study.

BACKGROUND: Although cardiovascular screening of kidney transplant candidates is recommended, the optimal approach is debated. Previous studies show that noninvasive imaging provides prognostic information, but systematic screening may have less recognized effects, such as additional investigations, incidental findings, procedural complications, and delay of transplantation. To address this, we characterized the diagnostic yield and clinical implications of systematic screening for cardiovascular disease using cardiac computed tomography (CT) in potential kidney transplant candidates. METHODS: This was a single-center, observational cohort study including all potential kidney transplant candidates >40 years of age or with diabetes or on dialysis treatment for >5 years, systematically referred to cardiac computed tomography (CT; non-contrast CT and coronary CT angiography) between 2014 and 2019 before evaluation for kidney transplantation at Aarhus University Hospital. Patient records were examined for data on baseline characteristics, additional investigations and complications, plasma creatinine, dialysis initiation, time until wait-listing, and incidental findings. RESULTS: Of 473 patients who underwent cardiac CT, additional cardiac investigations were performed in 156 (33%), and 32 (7%) were revascularized. Twenty-two patients had significant incidental nonvascular findings on cardiac CT. No patient was rejected for transplantation based on cardiac CT. In patients not yet on dialysis, the slope in the estimated glomerular filtration rate decline did not change significantly after coronary CT angiography. CONCLUSION: Screening by cardiac CT led to additional cardiac investigations in one-third of patients; only a few patients were revascularized, with unknown benefits in asymptomatic patients. Cardiac CT was safe in this population; however, the clinical consequences of the screening were limited.

Coronary Calcium Scoring Improves Risk Prediction in Patients With Suspected Obstructive Coronary Artery Disease.

BACKGROUND: In patients with suspected obstructive coronary artery disease (CAD), the risk factor-weighted clinical likelihood (RF-CL) model and the coronary artery calcium score-weighted clinical likelihood (CACS-CL) model improves the identification of obstructive CAD compared with basic pretest probability (PTP) models. OBJECTIVES: The aim of this study was to assess the prognostic value of the new models. METHODS: The incidences of myocardial infarction and death were stratified according to categories by the RF-CL and CACS-CL and compared with categories by the PTP model. We used cohorts from a Danish register (n = 41,177) and a North American randomized study (n = 3,952). All patients were symptomatic and were referred for diagnostic testing because of clinical indications. RESULTS: Despite substantial down-reclassification of patients to a likelihood ≤5% of CAD with either the RF-CL (45%) or CACS-CL (60%) models compared with the PTP (18%), the annualized event rates of myocardial infarction and death were low using all 3 models; RF-CL 0.51% (95% CI: 0.46-0.56), CACS-CL 0.48% (95% CI: 0.44-0.56), and PTP 0.37% (95% CI: 0.31-0.44), respectively. Overall, comparison of the predictive power of the 3 models using Harrell's C-statistics demonstrated superiority of the RF-CL (0.64 [95% CI: 0.63-0.65]) and CACS-CL (0.69 [95% CI: 0.67-0.70]) compared with the PTP model (0.61 [95% CI: 0.60-0.62]). CONCLUSIONS: The simple clinical likelihood models that include classical risk factors or risk factors combined with CACS provide improved risk stratification for myocardial infarction and death compared with the standard PTP model. Hence, the optimized RF-CL and CACS-CL models identify 2.5 and 3.3 times more patients, respectively, who may not benefit from further diagnostic testing.

Prognostic value of computed tomography derived fractional flow reserve for predicting cardiac events and mortality in kidney transplant candidates.

BACKGROUND: Cardiac screening using coronary computed tomography angiography (CCTA) in kidney transplant candidates before transplantation yields both diagnostic and prognostic information. Whether CT-derived fractional flow reserve (FFRCT) analysis provides prognostic information is unknown. This study aimed to assess the prognostic value of FFRCT for predicting major adverse cardiac events (MACE) and all-cause mortality in kidney transplant candidates. METHODS: Among 553 consecutive kidney transplant candidates, 340 CCTA scans (61%) were evaluated with FFRCT analysis. Patients were categorized into groups based on lowest distal FFRCT; normal >0.80, intermediate 0.80-0.76, and low ≤0.75. In patients with ≥50% stenosis, a lesion-specific FFRCT was defined as; normal >0.80 and abnormal ≤0.80. The primary endpoint was MACE (cardiac death, resuscitated cardiac arrest, myocardial infarction or revascularization). The secondary endpoint was all-cause mortality. RESULTS: Median follow-up was 3.3 years [2.0-5.1]. MACE occurred in 28 patients (8.2%), 29 patients (8.5%) died. When adjusting for risk factors and transplantation during follow-up, MACE occurred more frequently in patients with distal FFRCT ≤0.75 compared to patients with distal FFRCT >0.80: Hazard Ratio (HR): 3.8 (95%CI: 1.5-9.7), p â€‹< â€‹0.01. In the lesion-specific analysis with <50% stenosis as reference, patients with lesion-specific FFRCT >0.80 had a HR for MACE of 1.5 (95%CI: 0.4-4.8), p â€‹= â€‹0.55 while patients with lesion-specific FFRCT ≤0.80 had a HR of 6.0 (95%CI: 2.5-14.4), p â€‹< â€‹0.01. Abnormal FFRCT values were not associated with increased mortality. CONCLUSION: In kidney transplant candidates, abnormal FFRCT values were associated with increased MACE but not mortality. Use of FFRCT may improve cardiac evaluation prior to transplantation.