Observational Study
Copyright ©The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Cardiol. Mar 26, 2017; 9(3): 261-267
Published online Mar 26, 2017. doi: 10.4330/wjc.v9.i3.261
Significance of inferior wall ischemia in non-dominant right coronary artery anatomy
Ali Osama Malik, Oliver Abela, Subodh Devabhaktuni, Arhama Aftab Malik, Gayle Allenback, Chowdhury H Ahsan, Sanjay Malhotra, Jimmy Diep
Ali Osama Malik, Department of Internal Medicine, University of Nevada School of Medicine, Las Vegas, NV 89102, United States
Oliver Abela, Subodh Devabhaktuni, Chowdhury H Ahsan, Sanjay Malhotra, Jimmy Diep, Department of Cardiovascular Medicine, University of Nevada School of Medicine, Las Vegas, NV 89102, United States
Arhama Aftab Malik, Aga Khan Univesity Medical College, Karachi 74800, Pakistan
Gayle Allenback, Office of Medical Research, Universtiy of Nevada, School of Medicine, Las Vegas, NV 89102, United States
Author contributions: All the authors contributed to the paper.
Institutional review board statement: The institute review board at University Medical Center of Southern Nevada.
Informed consent statement: Not needed due to the non-clinical study design.
Conflict-of-interest statement: The authors declare no conflicts of interest regarding this manuscript.
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: Jimmy Diep, MD, Department of Cardiovascular Medicine, University of Nevada School of Medicine, 1701 West Charleston Boulevard, Suite 230, Las Vegas, NV 89102, United States. jdiep@medicine.nevada.edu
Telephone: +1-702-3832383
Received: August 31, 2016
Peer-review started: September 2, 2016
First decision: October 26, 2016
Revised: November 14, 2016
Accepted: December 16, 2016
Article in press: December 19, 2016
Published online: March 26, 2017
Abstract
AIM

To investigate the relationship of inferior wall ischemia on myocardial perfusion imaging in patients with non-dominant right coronary artery anatomy.

METHODS

This was a retrospective observational analysis of consecutive patients who presented to the emergency department with primary complaint of chest pain. Only patients who underwent single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) were included. Patients who showed a reversible defect on SPECT MPI and had coronary angiography during the same hospitalization was analyzed. Patients with prior history of coronary artery disease (CAD) including history of percutaneous coronary intervention and coronary artery bypass graft surgerys were excluded. True positive and false positive results were identified on the basis of hemodynamically significant CAD on coronary angiography, in the same territory as identified on SPECT MPI. Coronary artery dominance was determined on coronary angiography. Patients were divided into group 1 and group 2. Group 1 included patients with non-dominant right coronary artery (RCA) (left dominant and codominant). Group 2 included patients with dominant RCA anatomy. Demographics, baseline characteristics and positive predictive value (PPV) were analyzed for the two groups.

RESULTS

The mean age of the study cohort was 57.6 years. Sixty-one point seven percent of the patients were males. The prevalence of self-reported diabetes mellitus, hypertension and dyslipidemia was 36%, 71.9% and 53.9% respectively. A comparison of baseline characteristics between the two groups showed that patients with a non-dominant RCA were more likely to be men. For inferior wall ischemia on SPECT MPI, patients in study group 2 had a significantly higher PPV, 32/42 (76.1%), compared to patients in group 1, in which only 3 out of the 29 patients (10.3%) had true positive results (P value < 0.001 Z test). The difference remained statistically significant even when only patients with left dominant coronary system (without co-dominant) were compared to patients with right dominant system (32/40, 76.1% in right dominant group, 3/19, 15.8% in left dominant group, P value < 0.001 Z test). There was no significant difference in mean hospital stay, re-hospitalization, and in-hospital mortality between the two groups.

CONCLUSION

The positive predictive value of SPECT MPI for inferior wall ischemia is affected by coronary artery dominance. More studies are needed to explain this phenomenon.

Keywords: Myocardial perfusion imaging, Single photon emission commuted tomography, False positive results, Coronary artery dominance, Inferior wall ischemia

Core tip: A positive test for ischemia on single photon emission computed tomography (SPECT), myocardial perfusion imaging (MPI) is often followed up with coronary angiography. The aim of our study was to assess the relationship of inferior wall ischemia on SPECT MPI with non-dominant right coronary artery (RCA) anatomy. We found that positive predictive value of inferior wall ischemia on SPECT MPI was significantly lower in patients with non-dominant RCA anatomy. We postulate that in non-dominant RCA anatomy flow tracer may show relatively decreased uptake in the inferior wall that might not be indicative of flow limiting stenosis.