P6175Prediction of coronary revascularization by coronary computed tomography angiography derived fractional flow reserve - different algorithms for interpretation

Introduction

Coronary CT angiography (CTA) derived fractional flow reserve (FFRct) is increasingly used for guiding referral to invasive procedures in patients with stable chest pain. However, optimal interpretation of FFRct-analysis in terms of location and threshold of applied FFRct-values is unclear.

Purpose

To evaluate the clinical performance of various vessel-specific physiological FFRct derived measures of ischemia for prediction of standard of care guided coronary revascularization in patients with stable chest pain and coronary artery disease as determined by coronary CTA.

Methods

Retrospective study in patients with stable chest pain referred for coronary angiography based on coronary CTA. Standard acquired coronary CTA data sets were transmitted for core-laboratory analysis at HeartFlow. Any FFRct value in the major coronary arteries ≥1.8 mm in diameter, including side branches, were registered. Lesions were categorized as positive for ischemia using 6 different algorithms: Lowest in vessel FFRct-value (1) ≤0.75 or (2) ≤0.80; 2 cm distal-to-lesion FFRct-value (3) ≤0.75 or (4) ≤0.80; ΔFFRct (5) ≥0.06 or a combination of 2 and 5. The personnel responsible for downstream patient management had no information regarding FFRct test results.

Results

A total of 172 patients were included. Revascularization was performed in 62 (35%) patients. The diagnostic performance of different FFRct algorithms for predicting standard of care guided coronary revascularization is shown in the Table.

Revascularization Predictions by FFRct N=172 Diagnostic performance FFRCT false negative FFRCT false positive Values given as (%) No. of revasc vessels No. of abnormal vessels FFRCT Algorithm Sens Spec PPV NPV Acc 1 2 3 1 2 3 Distal FFRCT ≤0.75 77 68 58 84 72 12 2 0 29 5 1 Distal FFRCT ≤0.80 92 43 48 90 61 5 0 0 40 20 3 Lesion-specific FFRCT ≤0.75 68 86 74 83 80 17 3 0 12 3 0 Lesion-specific FFRCT ≤0.80 82 78 68 89 80 10 2 0 21 3 1 ΔFFRCT ≥0.06 98 36 47 98 59 1 0 0 51 19 0 Combinationa 92 54 53 92 67 5 0 0 39 12 0 aDistal FFRCT ≤0.80 and ΔFFRCT ≥0.06. Sens = sensitivity; Spec = specificity; PPV = positive predictive value; NPV = negative predictive value; Acc = accuracy; FFRCT = fractional flow reserve derived from coronary CTA; ΔFFRCT = difference between FFRCT-value immediately proximal and distal to lesion; Revasc = revascularized.

Conclusion

The diagnostic performance of FFRct in terms of predicting standard of care guided coronary revascularization is dependent on the applied algorithm for interpretation of the FFRct-analysis.

P6186Symptomatic effect of coronary revascularization at 1-year follow-up in stable chest pain - prediction by coronary computed tomography angiography derived fractional flow reserve

Introduction

Coronary CT angiography (CTA) derived fractional flow reserve (FFRct) is increasingly being used for guiding referral to invasive procedures in patients with stable chest pain. However, the ability of FFRct to predict the symptomatic effect of revascularization remains unclear.

Purpose

To evaluate the ability of different vessel-specific physiological FFRct derived measures of ischemia for predicting the occurrence of chest pain one year after coronary revascularization in stable patients.

Methods

Retrospective study in patients with stable chest pain referred for coronary angiography based on coronary CTA. Standard acquired coronary CTA data sets were transmitted for core-laboratory analysis at HeartFlow. Patients were categorized as positive for ischemia using 3 different algorithms: Lowest in vessel FFRct-value ≤0.80; ΔFFRct ≥0.06 or a combination of the two. Personnel responsible for downstream patient management had no information on FFRct test results. Classification of revascularization was performed based on the applied FFRct algorithm: complete if all FFRct positive lesions were revascularized; incomplete if ≥1 FFRct positive lesion was not revascularized. Symptomatic status at 1-year follow-up was obtained by a visit in the outpatient clinic or by telephone.

Results

A total of 172 patients were included. Revascularization was performed in 62 (35%) patients. At 1-year follow-up 48 (28%) patients had chest pain; 15 (24%) revascularized vs 33 (30%) non-vascularized patients, p=0.415. No difference in utilization of anti-anginal medicine for patients with and without chest pain was registered at 1-year follow-up. The association between the chosen FFRct algorithm, revascularization and occurrence of chest pain at 1-year follow-up are shown in the Table.

FFRct, Revascularization and Chest pain FFRCT, Algorithm Revascularizationb Patients with chest pain 1-year risk of chest pain p-valuec N (%) OR (95%-CI) Distal FFRCT ≤0.80 Incomplete 32 (34) Ref. Distal FFRCT ≤0.80 Complete 4 (15) 0.34 (0.11, 1.06) Distal FFRCT >0.80 No 11 (24) 0.61 (0.27, 1.35) 0.097 ΔFFRCT ≥0.06 Incomplete 34 (35) Ref. ΔFFRCT ≥0.06 Complete 7 (21) 0.49 (0.19, 1.24) ΔFFRCT <0.06 No 7 (18) 0.41 (0.16, 1.03) 0.074 Combinationa abnormal Incomplete 30 (40) Ref. Combination abnormal Complete 6 (18) 0.32 (0.12, 0.87) Combination normal No 11 (19) 0.35 (0.16, 0.78) 0.009 aDistal FFRCT ≤0.80 and ΔFFRCT ≥0.06. bIncomplete (≥1 FFRCT positive lesion not revascularized); complete (All FFRCT positive lesions revascularized); No (No FFRCT positive lesions and revascularization not performed). cBetween group comparison performed using logistic regression.

Conclusion

Revascularization based on classification by FFRct is associated with symptomatic relief at 1-year follow-up in patients with stable chest pain.