Published online Mar 26, 2017. doi: 10.4330/wjc.v9.i3.261
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
Processing time: 207 Days and 15.3 Hours
To investigate the relationship of inferior wall ischemia on myocardial perfusion imaging in patients with non-dominant right coronary artery anatomy.
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.
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.
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.
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.