Significance of inferior wall ischemia in non-dominant right coronary artery anatomy

Abstract

AIMTo investigate the relationship of inferior wall ischemia on myocardial perfusion imaging in patients with non-dominant right coronary artery anatomy.METHODSThis 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.RESULTSThe 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.CONCLUSIONThe positive predictive value of SPECT MPI for inferior wall ischemia is affected by coronary artery dominance. More studies are needed to explain this phenomenon.

The Relationship Between Coronary Dominance and Positive Results in Myocardial Perfusion Imaging

“…Our study demonstrated additional evidence that SPECT MPI in detecting inferior/inferior-lateral wall ischemia has a statistically significant higher incidence of false positive studies with left or codominant coronary circulation compared to its right dominant counterpart. This finding was previously described in an observational study in which the authors hypothesized that the flow tracer in a left dominant or codominant circulation may show relatively decreased uptake in the inferior wall that might not be indicative of flow-limiting stenosis [ 3 ]. In addition, anatomical variation in vessel size might also be contributing to this observed phenomenon [ 3 ].…”

“…This finding was previously described in an observational study in which the authors hypothesized that the flow tracer in a left dominant or codominant circulation may show relatively decreased uptake in the inferior wall that might not be indicative of flow-limiting stenosis [ 3 ]. In addition, anatomical variation in vessel size might also be contributing to this observed phenomenon [ 3 ].…”

“…SPECT MPI remains a widely used modality to analyze myocardial perfusion with a sensitivity of 0.83 and a specificity of 0.77 according to a meta-analysis conducted by Marcus et al [ 5 ]. MPI plays an important role in clinical decision-making as a gatekeeper for further intervention and has been proven to be a cost-effective non-invasive imaging modality to evaluate for the presence of obstructive coronary artery disease [ 3 ]. However, nuclear perfusion imaging is subject to a variety of artifacts and pitfalls, which may affect its clinical utility.…”

“…Approximately 70%-80% of the general population are right dominant, 5%-12% are left dominant and the remainder is codominant [ 2 ]. Previous studies have explored the potential effect of coronary dominance on the accuracy of single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) tests in detecting inferior/inferior-lateral wall ischemia, Ali et al showed more false positive MPI results were noted in non-right dominant circulation in detecting inferior/inferior-lateral wall ischemia [ 3 ]. However, more studies are needed to confirm those findings.…”

Resting coronary flow estimated by dynamic coronary CT angiography: Potential for use in the detection of plaque burden and myocardial ischemia

“…When the optimal cutoff of rCFI was used to diagnose ischemia, the sensitivity was only 53%, but the speci city was 93%. One of the reasons for the low sensitivity is the presence of false positives in the inferior wall of the left ventricle on SPECT; that is, in the RCA territory 23 . In our study, the rCFI for the RCA ischemia depicted by SPECT (n = 7) was 0.81 ± 0.21.…”