Coronary computed tomography angiography derived fractional flow reserve and risk of recurrent angina: A 3-year follow-up study

BACKGROUND

The association between coronary computed tomography angiography (CTA) derived fractional flow reserve (FFRCT) and risk of recurrent angina in patients with new onset stable angina pectoris (SAP) and stenosis by CTA is uncertain.

METHODS

Multicenter 3-year follow-up study of patients presenting with symptoms suggestive of new onset SAP who underwent first-line CTA evaluation and subsequent standard-of-care treatment. All patients had at least one ≥30 ​% coronary stenosis. A per-patient lowest FFRCT-value ≤0.80 represented an abnormal test result. Patients with FFRCT ≤0.80 who underwent revascularization were categorized according to completeness of revascularization: 1) Completely revascularized (CR-FFRCT), all vessels with FFRCT ≤0.80 revascularized; or 2) incompletely revascularized (IR-FFRCT) ≥1 vessels with FFRCT ≤0.80 non-revascularized. Recurrent angina was evaluated using the Seattle Angina Questionnaire.

RESULTS

Amongst 769 patients (619 [80 ​%] stenosis ≥50 ​%, 510 [66 ​%] FFRCT ≤0.80), 174 (23 ​%) reported recurrent angina at follow-up. An FFRCT ≤0.80 vs ​> ​0.80 associated to increased risk of recurrent angina, relative risk (RR): 1.82; 95 ​% CI: 1.31-2.52, p ​< ​0.001. Risk of recurrent angina in CR-FFRCT (n ​= ​135) was similar to patients with FFRCT >0.80, 13 ​% vs 15 ​%, RR: 0.93; 95 ​% CI: 0.62-1.40, p ​= ​0.72, while IR-FFRCT (n ​= ​90) and non-revascularized patients with FFRCT ≤0.80 (n ​= ​285) had increased risk, 37 ​% vs 15 ​% RR: 2.50; 95 ​% CI: 1.68-3.73, p ​< ​0.001 and 30 ​% vs 15 ​%, RR: 2.03; 95 ​% CI: 1.44-2.87, p ​< ​0.001, respectively. Use of antianginal medication was similar across study groups.

CONCLUSION

In patients with SAP and coronary stenosis by CTA undergoing standard-of-care guided treatment, FFRCT provides information regarding risk of recurrent angina.

Predictors of percutaneous coronary intervention derived from CCTA in patients with chronic coronary syndrome

BACKGROUND

To identify anatomical and morphological plaque features predictors of PCI and create a multiparametric score to increase the predictive yield. Moreover, we assessed the incremental predictive value of FFRCT (Fractional Flow Reserve derived from CCTA) trans-lesion gradient (ΔFFRCT) when integrated into the score.

METHODS

Observational cohort study including patients undergoing CCTA for suspected coronary artery disease, with FFRCT available, referred to invasive coronary angiogram and assessment of fractional flow reserve. Plaque analysis was performed using validated semi-automated software. Logistic regression was performed to identify anatomical and morphological plaque features predictive of PCI. Optimal thresholds were defined by area under the receiver-operating characteristics curve (AUC) analysis. A scoring system was developed in a derivation cohort (70 ​% of the study population) and tested in a validation cohort (30 ​% of patients).

RESULTS

The overall study population included 340 patients (455 vessels), among which 238 patients (320 vessels) were included in the derivation cohort. At multivariate logistic regression analysis, absence of left main disease, diameter stenosis (DS), non-calcified plaque (NCP) volume, and percent atheroma volume (PAV) were independent predictors of PCI. Optimal thresholds were: DS ​≥ ​50 ​%, volume of NCP>113 ​mm3 and PAV>17 ​%. A weighted score (CT-PCI Score) ranging from 0 to 11 was obtained. The AUC of the score was 0.80 (95%CI 0.74-0.86). The integration of ΔFFRCT in the CT-PCI score led to a mild albeit not significant increase in the AUC (0.82, 95%CI 0.77-0.87, p ​= ​0.328).

CONCLUSIONS

Plaque anatomy and morphology derived from CCTA could aid in identifying patients amenable to PCI.

Diagnostic value of comprehensive on-site and off-site coronary CT angiography for identifying hemodynamically obstructive coronary artery disease

BACKGROUND

This study aimed to investigate the diagnostic value of comprehensive on-site coronary computed tomography angiography (CCTA) using stenosis and plaque measures and subtended myocardial mass (V_sub) for fractional flow reserve (FFR) defined hemodynamically obstructive coronary artery disease (CAD). Additionally, the incremental diagnostic value of off-site CT-derived FFR (FFR_CT) was assessed.

METHODS

Prospectively enrolled patients underwent CCTA followed by invasive FFR interrogation of all major coronary arteries. Vessels with ≥30% stenosis were included for analysis. On-site CCTA assessment included qualitative and quantitative stenosis (visual grading and minimal lumen area, MLA) and plaque measures (characteristics and volumes), and V_sub. Diagnostic value of comprehensive on-site CCTA assessment was tested by comparing area under the curves (AUC). In vessels with available FFR_CT, the incremental value of off-site FFR_CT was tested.

RESULTS

In 236 vessels (132 patients), MLA, positive remodeling, non-calcified plaque volume, and V_sub were independent on-site CCTA predictors for hemodynamically obstructive CAD (p < 0.05 for all). V_sub/MLA² outperformed all these on-site CCTA parameters (AUC = 0.85) and V_sub was incremental to all other CCTA predictors (p = 0.02). In subgroup analysis (n = 194 vessels), diagnostic performance of FFR_CT and V_sub/MLA² was similar (AUC 0.89 and 0.85 respectively, p = 0.25). Furthermore, diagnostic performance significantly albeit minimally increased when FFR_CT was added to on-site CCTA assessment (ΔAUC = 0.03, p = 0.02).

CONCLUSIONS

In comprehensive on-site CCTA assessment, V_sub/MLA2 demonstrated greatest diagnostic value for hemodynamically obstructive CAD and V_sub was incremental to all evaluated CCTA indices. Additionally, adding FFR_CT only minimally increased diagnostic performance, demonstrating that on-site CCTA assessment is a reasonable alternative to FFR_CT.

FFRCT and CT perfusion: A review on the evaluation of functional impact of coronary artery stenosis by cardiac CT. Int J Cardiol. 2020;300:289-296. [PMID: 31466886 DOI: 10.1016/j.ijcard.2019.08.018]

Coronary computed tomography angiography (CCTA) is at the frontline of the diagnostic strategies to detect coronary artery disease (CAD). Anatomical information have proven to be insufficient to detect hemodynamic significant epicardial stenosis. In the present invited review we discuss on FFR_CT and stress CTP, emerging technologies for an accurate and comprehensive evaluation of patients with suspected CAD, offering both anatomical (i.e. luminal and plaque) and functional assessment in one single technique.

Clinical Use of CT-Derived Fractional Flow Reserve in the Emergency Department

OBJECTIVES

This study sought to examine the feasibility, safety, clinical outcomes, and costs associated with computed tomography-derived fractional flow reserve (FFR_CT) in acute chest pain (ACP) patients in a coronary computed tomography angiography (CTA)-based triage program.

BACKGROUND

FFR_CT is useful in determining lesion-specific ischemia in patients with stable ischemic heart disease, but its utility in ACP has not been studied.

METHODS

ACP patients with no known coronary artery disease undergoing coronary CTA and coronary CTA with FFR_CT were studied. FFR_CT ≤0.80 was considered positive for hemodynamically significant stenosis.

RESULTS

Among 555 patients, 297 underwent coronary CTA and FFR_CT (196 negative, 101 positive), whereas 258 had coronary CTA only. The rejection rate for FFR_CT was 1.6%. At 90 days, there was no difference in major adverse cardiac events (including death, nonfatal myocardial infarction, and unexpected revascularization after the index visit) between the coronary CTA and FFR_CT groups (4.3% vs. 2.7%; p = 0.310). Diagnostic failure, defined as discordance between the coronary CTA or FFR_CT results with invasive findings, did not differ between the groups (1.9% vs. 1.68%; p = NS). No deaths or myocardial infarction occurred with negative FFR_CT when revascularization was deferred. Negative FFR_CT was associated with higher nonobstructive disease on invasive coronary angiography (56.5%) than positive FFR_CT (8.0%) and coronary CTA (22.9%) (p < 0.001). There was no difference in overall costs between the coronary CTA and FFR_CT groups ($8,582 vs. $8,048; p = 0.550).

CONCLUSIONS

In ACP, FFR_CT is feasible, with no difference in major adverse cardiac events and costs compared with coronary CTA alone. Deferral of revascularization is safe with negative FFR_CT, which is associated with higher nonobstructive disease on invasive angiography.

Hypertrophic Cardiomyopathy (HCM): New insights into Coronary artery remodelling and ischemia from FFRCT

INTRODUCTION

Angina, myocardial ischemia, and coronary artery physiology in hypertrophic cardiomyopathy (HCM) are poorly understood. However, coronary computed tomography angiography (CCTA) with fractional flow reserve from CT (FFR_CT) analysis offers a non-invasive method for evaluation of coronary artery volume to myocardial mass ratio (V/M) that may provide insight into such mechanisms. Thus, we sought to investigate changes in V/M in HCM.

METHODS

A retrospective analysis was performed on 37 HCM patients and 37 controls matched for age, sex, and cardiovascular risk factors; CCTA-derived coronary artery lumen volume (V) and myocardial mass (M) were used to determine V/M. FFR_CT values were calculated for the left anterior descending (LAD), left circumflex (LCx) and right coronary (RCA) arteries as well as the 3-vessel cumulative FFR_CT values.

RESULTS

HCM patients had significantly increased myocardial mass (176 ± 84 vs. 119 ± 27 g, p < 0.0001) and total coronary artery luminal volume (4112 ± 1139 vs. 3290 ± 924 mm³, p < 0.0001) that resulted from increases in segmented luminal volumes of both the left and right coronary artery systems. However, HCM patients had significantly decreased V/M (23.8 ± 5.9 vs. 26.5 ± 5.3 mm³/g; p = 0.026) which was further decreased when restricting V/M analysis to those HCM patients with septal hypertrophy (22.4 mm³/g, p = 0.01) that was mild-moderately predictive of HCM (AUC = 0.68). HCM patients also showed significantly lower nadir FFR_CT values in the LCx (0.87 ± 0.06 vs. 0.91 ± 0.06, p = 0.02), and cumulative 3-vessel FFR_CT values (2.58 ± 0.18 vs. 2.63 ± 0.14, p = 0.006).

CONCLUSIONS

HCM patients demonstrate significantly greater coronary volume. Despite this, HCM patients suffer from decreased V/M. Further prospective studies evaluating the relationship between V/M, angina, and heart failure in HCM are needed.

Prospective Comparison of FFR Derived From Coronary CT Angiography With SPECT Perfusion Imaging in Stable Coronary Artery Disease: The ReASSESS Study

OBJECTIVES

This study sought to compare the per-patient diagnostic performance of coronary computed tomography angiography (CTA)-derived fractional flow reserve (FFR_CT) with that of single-photon emission computed tomography (SPECT), using a fractional flow reserve (FFR) value of ≤0.80 as the reference for diagnosing at least 1 hemodynamically significant stenosis in a head-to-head comparison of patients with intermediate coronary stenosis as determined by coronary CTA.

BACKGROUND

No previous study has prospectively compared the diagnostic performance of FFR_CT and myocardial perfusion imaging by SPECT in symptomatic patients with intermediate range coronary artery disease (CAD).

METHODS

This study was conducted at a single-center as a prospective study in patients with stable angina pectoris (N = 143). FFR_CT and SPECT analyses were performed by core laboratories and were blinded for the personnel responsible for downstream patient management. FFR_CT ≤0.80 distally in at least 1 coronary artery with a diameter ≥2 mm classified patients as having ischemia. Ischemia by SPECT was encountered if a reversible perfusion defect (summed difference score ≥2) or transitory ischemic dilation of the left ventricle (ratio >1.19) were found.

RESULTS

The per-patient diagnostic performance for identifying ischemia (95% confidence interval [CI]), FFR_CT versus SPECT, were sensitivity of 91% (95% CI: 81% to 97%) versus 41% (95% CI: 29% to 55%; p < 0.001); specificity of 55% (95% CI: 44% to 66%) versus 86% (95% CI: 77% to 93%; p < 0.001); negative predictive value of 90% (95% CI: 82% to 98%) versus 68% (95% CI: 59% to 77%; p = 0.001); positive predictive value of 58% (95% CI: 48% to 68%) versus 67% (95% CI: 51% to 82%; p = NS); and accuracy of 70% (95% CI: 62% to 77%) versus 68% (95% CI: 60% to 75%; p = NS) respectively.

CONCLUSIONS

In patients with stable chest pain and CAD as determined by coronary CTA, the overall diagnostic accuracy levels of FFR_CT and SPECT were identical in assessing hemodynamically significant stenosis. However, FFR_CT demonstrated a significantly higher diagnostic sensitivity than SPECT.

Coronary lumen volume to myocardial mass ratio in primary microvascular angina

BACKGROUND

Microvascular angina (MVA) is an incompletely understood clinical entity. Computational analysis of coronary Computed Tomography Angiography (CTA) has shown an association between low coronary lumen volume to myocardial mass (V/M) ratio and lower Fractional Flow Reserve values, independent of plaque measures. We hypothesized that low V/M ratio may be present in patients with MVA.

METHODS

A retrospective case-control analysis was performed using patients fulfilling guideline criteria for MVA with controls matched for age, gender, coronary risk factors and atherosclerotic plaque burden. V/M was extracted off site (Heartflow Inc; Redwood City, CA) employing allometric scaling laws that allow the definition of the coronary circulation beyond the epicardium. FFR_CT values were calculated in the major epicardial coronary arteries for each group.

RESULTS

A total of 30 patients with MVA and 32 matched controls were included in the study. Mean total coronary lumen volume (2302 mm³ ± 109 vs 2978 mm³ ± 134, p < 0.001) and mean myocardial mass (90.4 g ± 13.7 vs 100.4 g ± 20.1, p = 0.029) were lower in MVA patients compared to controls. Mean V/M ratio was significantly lower in MVA compared to controls (25.6 mm³/g ± 5.9 vs 30.0 mm³/g ± 6.5, p = 0.007; c-statistic 0.69). V/M ratio did not differ significantly between subclasses of angina severity (p = 0.747). No difference in mean nadir FFR_CT values was found between MVA and control groups in the LAD (0.86 ± 0.07 vs 0.83 ± 0.07, p = 0.154), LCX (0.90 ± 0.05 vs 0.90 ± 0.06, p = 0.240) and RCA (0.90 ± 0.04 vs 0.90 ± 0.03, p = 0.773) vessels.

CONCLUSION

Patients with microvascular angina demonstrate a significantly lower coronary CTA-derived coronary volume/myocardial mass ratio than asymptomatic controls.

Noninvasive Fractional Flow Reserve Derived from Coronary Computed Tomography Angiography for the Diagnosis of Lesion-specific Ischemia

Fractional flow reserve derived from coronary computed tomography angiography (FFR_CT) has emerged as a powerful tool for the assessment of flow-limiting coronary stenoses. To date, FFR_CT is the only noninvasive imaging modality for the depiction of lesion-specific ischemia and large prospective multicenter studies have established its high diagnostic value. The nature of FFR_CT allows the prediction of functional outcome of coronary stenting, which will expand the role of cardiac computed tomography in the evaluation and management of coronary artery disease.

Five-year clinical and functional multislice computed tomography angiographic results after coronary implantation of the fully resorbable polymeric everolimus-eluting scaffold in patients with de novo coronary artery disease: the ABSORB cohort A trial

OBJECTIVES

This study sought to demonstrate the 5-year clinical and functional multislice computed tomography angiographic results after implantation of the fully resorbable everolimus-eluting scaffold (Absorb BVS, Abbott Vascular, Santa Clara, California).

BACKGROUND

Multimodality imaging of the first-in-humans trial using a ABSORB BVS scaffold demonstrated at 2 years the bioresorption of the device while preventing restenosis. However, the long-term safety and efficacy of this therapy remain to be documented.

METHODS

In the ABSORB cohort A trial (ABSORB Clinical Investigation, Cohort A [ABSORB A] Everolimus-Eluting Coronary Stent System Clinical Investigation), 30 patients with a single de novo coronary artery lesion were treated with the fully resorbable everolimus-eluting Absorb scaffold at 4 centers. As an optional investigation in 3 of the 4 centers, the patients underwent multislice computed tomography (MSCT) angiography at 18 months and 5 years. Acquired MSCT data were analyzed at an independent core laboratory (Cardialysis, Rotterdam, the Netherlands) for quantitative analysis of lumen dimensions and was further processed for calculation of fractional flow reserve (FFR) at another independent core laboratory (Heart Flow, Redwood City, California).

RESULTS

Five-year clinical follow-up is available for 29 patients. One patient withdrew consent after 6 months, but the vital status of this patient remains available. At 46 days, 1 patient experienced a single episode of chest pain and underwent a target lesion revascularization with a slight troponin increase after the procedure. At 5 years, the ischemia-driven major adverse cardiac event rate of 3.4% remained unchanged. Clopidogrel was discontinued in all but 1 patient. Scaffold thrombosis was not observed in any patient. Two noncardiac deaths were reported, 1 caused by duodenal perforation and the other from Hodgkin's disease. At 5 years, 18 patients underwent MSCT angiography. All scaffolds were patent, with a median minimal lumen area of 3.25 mm(2) (interquartile range: 2.20 to 4.30). Noninvasive FFR analysis was feasible in 13 of 18 scans, which yielded a median distal FFR of 0.86 (interquartile range: 0.82 to 0.94).

CONCLUSIONS

The low event rate at 5 years suggests sustained safety after the implantation of a fully bioresorbable Absorb everolimus-eluting scaffold. Noninvasive assessment of the coronary artery with an option of functional assessment could be an alternative to invasive imaging after treatment of coronary narrowing with such a polymeric bioresorbable scaffold. (ABSORB Clinical Investigation, Cohort A [ABSORB A] Everolimus-Eluting Coronary Stent System Clinical Investigation [ABSORB]; NCT00300131).