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Copyright ©The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Cardiol. Dec 26, 2017; 9(12): 813-821
Published online Dec 26, 2017. doi: 10.4330/wjc.v9.i12.813
Delineation of epicardial stenosis in patients with microvascular disease using pressure drop coefficient: A pilot outcome study
Ullhas Udaya Hebbar, Mohamed A Effat, Srikara V Peelukhana, Imran Arif, Rupak K Banerjee
Ullhas Udaya Hebbar, Department of Mechanical and Materials Engineering, University of Cincinnati, Cincinnati, OH 45221, United States
Mohamed A Effat, Imran Arif, Division of Cardiovascular Diseases, University of Cincinnati Medical Center, Veteran Affairs Medical Center, Cincinnati, OH 45221, United States
Srikara V Peelukhana, Department of Mechanical and Materials Engineering, University of Cincinnati, Veteran Affairs Medical Center, Cincinnati, OH 45221, United States
Rupak K Banerjee, Department of Mechanical and Materials Engineering, Veteran Affairs Medical Center, Cincinnati, OH 45221, United States
Author contributions: Hebbar UU, Effat MA, Peelukhana SV and Banerjee RK designed the research; Effat MA and Arif I performed the interventions; Banerjee RK assimilated the data; Hebbar UU and Peelukhana SV performed the data analysis; Hebbar UU, Effat MA, Peelukhana SV and Banerjee RK wrote the paper.
Supported by VA Merit Review Grant, Department of Veteran Affairs (PI: Dr. Rupak K Banerjee), No. I01CX000342-01.
Institutional review board statement: The study protocol was approved by the institutional review board at University of Cincinnati (UC) and the research and development committee at the Cincinnati Veteran Affairs Medical Center (CVAMC).
Clinical trial registration statement: The study was registered with Clinicaltrials.gov. The registration identification number is NCT01719016.
Informed consent statement: All study participants provided informed written consent prior to the study enrolment.
Conflict-of-interest statement: The authors report no financial relationships or conflicts of interest regarding the content herein.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Rupak K Banerjee, PhD, PE, Professor, Department of Mechanical and Materials Engineering, Veteran Affairs Medical Center, 598 Rhodes Hall, PO Box 0072, Cincinnati, OH 45221, United States. rupak.banerjee@uc.edu
Telephone: +1-513-5562124 Fax: +1-513-5563390
Received: July 21, 2017
Peer-review started: July 27, 2017
First decision: September 5, 2017
Revised: September 29, 2017
Accepted: October 29, 2017
Article in press: October 29, 2017
Published online: December 26, 2017
Processing time: 148 Days and 12.9 Hours
Abstract
AIM

To investigate the patient-outcomes of newly developed pressure drop coefficient (CDP) in diagnosing epicardial stenosis (ES) in the presence of concomitant microvascular disease (MVD).

METHODS

Patients from our clinical trial were divided into two subgroups with: (1) cut-off of coronary flow reserve (CFR) < 2.0; and (2) diabetes. First, correlations were performed for both subgroups between CDP and hyperemic microvascular resistance (HMR), a diagnostic parameter for assessing the severity of MVD. Linear regression analysis was used for these correlations. Further, in each of the subgroups, comparisons were made between fractional flow reserve (FFR) < 0.75 and CDP > 27.9 groups for assessing major adverse cardiac events (MACE: Primary outcome). Comparisons were also made between the survival curves for FFR < 0.75 and CDP > 27.9 groups. Two tailed chi-squared and Fischer’s exact tests were performed for comparison of the primary outcomes, and the log-rank test was used to compare the Kaplan-Meier survival curves. P < 0.05 for all tests was considered statistically significant.

RESULTS

Significant linear correlations were observed between CDP and HMR for both CFR < 2.0 (r = 0.58, P < 0.001) and diabetic (r = 0.61, P < 0.001) patients. In the CFR < 2.0 subgroup, the %MACE (primary outcomes) for CDP > 27.9 group (7.7%, 2/26) was lower than FFR < 0.75 group (3/14, 21.4%); P = 0.21. Similarly, in the diabetic subgroup, the %MACE for CDP > 27.9 group (12.5%, 2/16) was lower than FFR < 0.75 group (18.2%, 2/11); P = 0.69. Survival analysis for CFR < 2.0 subgroup indicated better event-free survival for CDP > 27.9 group (n = 26) when compared with FFR < 0.75 group (n = 14); P = 0.10. Similarly, for the diabetic subgroup, CDP > 27.9 group (n = 16) showed higher survival times compared to FFR group (n = 11); P = 0.58.

CONCLUSION

CDP correlated significantly with HMR and resulted in better %MACE as well as survival rates in comparison to FFR. These positive trends demonstrate that CDP could be a potential diagnostic endpoint for delineating MVD with or without ES.

Keywords: Fractional flow reserve, Pressure drop coefficient, Microvascular disease, Intermediate coronary stenosis, Interventional cardiology

Core tip: Fractional flow reserve (FFR), a functional diagnostic index, is currently the gold standard for decision making in the catheterization laboratory. However, FFR can be confounded by concomitant microvascular disease (MVD). In this subgroup analysis study, pressure drop coefficient (CDP) showed improved clinical outcomes for patients with MVD compared to FFR, potentially making CDP a better diagnostic endpoint compared to FFR.