Association of quantitative flow ratio-derived microcirculatory indices with anatomical-functional discordance in intermediate coronary lesions

Discrepancy between coronary lesion severity and functional significance has always been a relevant issue in the management of patients undergoing coronary angiography and/or revascularization. We sought to investigate the relationship between quantitative flow ratio (QFR)-derived microcirculatory indices and anatomical-functional mismatch/reverse mismatch in intermediate coronary lesions. Intravascular ultrasound (IVUS) imaging and QFR were analyzed in 117 de novo intermediate coronary lesions. Lesions with QFR ≤ 0.8 were considered hemodynamically significant. Anatomical significance of the lesions was defined according to the best cutoff value of combined IVUS parameters for predicting QFR ≤ 0.8. QFR-derived microcirculatory indices including contrast-flow QFR minus fixed-flow QFR (cQFR-fQFR), hyperemic flow velocity and angiography-derived index of microcirculatory resistance (IMR_angio) were calculated. The best cutoff values of IVUS parameters for predicting QFR ≤ 0.8 were minimum lumen area (MLA) 3.1mm² and plaque burden (PB) 70%, with area under the curve of 0.635 and 0.703, respectively. The total discordance rate of lesion functional significance between IVUS and QFR assessments was 26.5%, with 21 lesions (17.9%) being classified as mismatch (MLA ≤ 3.1mm² and PB ≥ 70% and QFR > 0.8) and 10 lesions (8.5%) as reverse-mismatch (MLA > 3.1 mm² or PB < 70% and QFR ≤ 0.8). At multivariate analysis, IMR_angio was identified as an independent predictor of mismatch (OR1.675, 95%CI:1.176-2.386, P = 0.004), whereas hyperemic flow velocity was identified as an independent predictor of reverse-mismatch (OR 1.233, 95%CI:1.073-1.416, P = 0.003). In intermediate coronary lesions, although MLA 3.1mm² and PB 70% determined by IVUS are predictive of QFR-defined functional significance, the discordance rate remains substantial. QFR-derived microcirculatory indices are independently associated with anatomical-functional discordance between IVUS and QFR assessments.

Utility of Imaging Modalities in Coronary Lesions With Borderline Fractional Flow Reserve

BACKGROUND

Coronary intervention is routinely deferred in intermediate lesions with fractional flow reserve (FFR) ≥ 0.80. Patients with borderline FFR (0.80-0.85) who were initially deferred, have been shown to have higher risk of future interventions; however, the data is limited, and the long term prognosis in these patients remains unknown. We assessed the utility of adjunctive imaging modalities to determine the need for intervention in lesions with borderline FFR.

METHODS

We retrospectively evaluated consecutive patients who underwent coronary angiography at Einstein Medical Center from January 2013 to April 2016. All patients with borderline FFR (0.80-0.85) were included. Patients were divided into Defer or Perform intervention groups based on additional available or procured clinical data. The Perform group was further stratified into intervention With or Without adjunctive imaging guidance (including intravascular ultrasound, optical coherence tomography, echocardiography, and exercise or pharmacologic stress test). Follow-up data was collected for all patients, which included future target lesion revascularization (TLR) and major adverse cardiac events (MACE; all-cause and cardiovascular mortality and acute coronary syndromes).

RESULTS

A total of 196 patients were eligible. Median (IQR) FFR in Perform and Defer groups was 0.81 (0.8-0.83) and 0.84 (0.82-0.85) respectively. Median (IQR) follow up was 21 (13-29) and 25 (15-36) months respectively. Overall MACE rate in Perform group (n = 101) was 20.8% (n = 21) and Defer group (n = 95) was 15.8% (n = 15). The stratified MACE rate in Perform group With imaging guidance (n = 57) was 17.5% (n = 10) and Without imaging guidance (n = 44) was 25% (n = 11). Overall, the FFR only guided management (n = 196) led to MACE rate of 18.4% (n = 36); whereas, FFR With imaging guidance (n = 136) led to MACE rate of 16.2% (n = 22). The p values were non-significant in each of the above group comparisons due to relatively low numbers with trends as noted.

CONCLUSIONS

Our study suggests that intervention of coronary lesions with borderline FFR under imaging guidance, although not significant, trends towards improved cardiovascular outcomes compared with intervention in this group without adjunctive imaging. These findings are merely speculative without achieving statistical significance in a small subset and need to be further validated in a large scale prospective study.

Tissue characterization of non-culprit intermediate coronary lesions in non ST elevation acute coronary syndromes

Background

Disruption of vulnerable plaques is the most common cause of acute coronary syndromes. Intravascular ultrasound facilitates cross-sectional imaging of coronary arteries. We aimed at using IVUS to investigate the morphology and tissue characteristics of atherosclerotic plaques of non-culprit intermediate coronary lesions in non-ST elevation ACS setting.

Methods

IVUS assessment of sixty-one intermediate coronary lesions in twenty-eight patients with the diagnosis of Non ST elevation acute coronary syndromes. Ultrasound signals were obtained by an IVUS system using a 40-MHz catheter.

Results

Mean age was 53.2 ± 9.1 years. Males = 20 (71.4%). Smoking in 17 (60.7%), hypertension in 16 (57.1%), Dyslipidemia in 12 (42.9%) and DM in 8 (28.6%). Culprit vessels represent 42% of affected vessels. Sixty-one intermediate lesions were detected. Twenty-nine lesions in culprit vessels and thirty-two lesions in non-culprit vessels with higher lipidic content in lesions of culprit vessels (P < 0.001) while a higher calcific content in lesions of non-culprit vessels (P < 0.001). Higher calcific content of proximal more than distal lesions (P = 0.048). Negative remodeling in 55.7% of lesions.

Conclusions

A higher lipidic content in lesions of culprit vessels, while the lesions of non-culprit vessels were more calcific. Higher calcific content of proximal more than distal lesions was defined as well.

Intravascular ultrasound-based analysis of factors affecting minimum lumen area in coronary artery intermediate lesions

OBJECTIVE

To identify clinical characteristics associated with the minimum lumen area (MLA) of proximal or middle intermediate lesions in the left anterior descending (LAD) artery, and to develop a model to predict MLA.

METHODS

We retrospectively analyzed demographic data, medical history, and intravascular ultrasound findings for 90 patients with intermediate lesions in the LAD artery. Linear regression was used to identify factors affecting MLA, and multiple regression was used to develop a model for predicting MLA.

RESULTS

Age, number of lesions, and diabetes mellitus correlated significantly with MLA of proximal or middle intermediate lesions. A regression model for predicting MLA (mm(2)) was derived from the data: 7.00 - 0.05 × (age) - 0.50 × (number of lesions). A cut-off value of 3.1 mm(2) was proposed for deciding when to perform percutaneous coronary intervention.

CONCLUSION

This model for predicting MLA of proximal or middle intermediate lesions in the LAD artery showed high accuracy, sensitivity, and specificity, indicating good diagnostic potential.