title: Significance of inferior wall ischemia in non-dominant right coronary artery anatomy.
abstract: OBJECTIVE
  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 (Pvalue < 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,Pvalue < 0.001 Z test). There was no significant difference in mean hospital stay, re-hospitalization, and in-hospital mortality between the two groups.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Ali Osama Malik, Department of Internal Medicine, University of Nevada School of Medicine, Las Vegas, NV 89102, United States.
authors.forename: Ali Osama
authors.initials: AO
authors.lastname: Malik
authors.affiliation: Ali Osama Malik, Department of Internal Medicine, University of Nevada School of Medicine, Las Vegas, NV 89102, United States.
authors.forename: Oliver
authors.initials: O
authors.lastname: Abela
authors.affiliation: Ali Osama Malik, Department of Internal Medicine, University of Nevada School of Medicine, Las Vegas, NV 89102, United States.
authors.forename: Subodh
authors.initials: S
authors.lastname: Devabhaktuni
authors.affiliation: Ali Osama Malik, Department of Internal Medicine, University of Nevada School of Medicine, Las Vegas, NV 89102, United States.
authors.forename: Arhama Aftab
authors.initials: AA
authors.lastname: Malik
authors.affiliation: Ali Osama Malik, Department of Internal Medicine, University of Nevada School of Medicine, Las Vegas, NV 89102, United States.
authors.forename: Gayle
authors.initials: G
authors.lastname: Allenback
authors.affiliation: Ali Osama Malik, Department of Internal Medicine, University of Nevada School of Medicine, Las Vegas, NV 89102, United States.
authors.forename: Chowdhury H
authors.initials: CH
authors.lastname: Ahsan
authors.affiliation: Ali Osama Malik, Department of Internal Medicine, University of Nevada School of Medicine, Las Vegas, NV 89102, United States.
authors.forename: Sanjay
authors.initials: S
authors.lastname: Malhotra
authors.affiliation: Ali Osama Malik, Department of Internal Medicine, University of Nevada School of Medicine, Las Vegas, NV 89102, United States.
authors.forename: Jimmy
authors.initials: J
authors.lastname: Diep
keywords: Coronary artery dominance; False positive results; Inferior wall ischemia; Myocardial perfusion imaging; Single photon emission commuted tomography