Detection of perfusion abnormalities in patients with permanent pacemakers on stress–rest 99mTc-tetrofosmin myocardial perfusion single-photon emission computed tomography

OBJECTIVE: The aim of the study was to compare the myocardial perfusion defects in patients with right ventricular outflow tract (RVOT) and right ventricular apex (RVA) pacing on stress-rest Tc-tetrofosmin myocardial perfusion single-photon emission computed tomography. PATIENTS AND METHODS: A total of 31 patients with permanent pacemakers (RVOT: 16 and RVA: 15) underwent stress-rest Tc-tetrofosmin involving a 1-day protocol. All patients underwent 1-day low-dose stress-gated and high-dose rest-gated Tc-tetrofosmin myocardial perfusion single-photon emission computed tomography imaging. RESULTS: Fixed perfusion defects were noted in 13 (42%) of 31 patients. Two (13%) patients of the RVOT group and 11 (69%) patients of the RVA group showed fixed perfusion defects (P=0.003). The fixed perfusion defects were located in the anteroapical, anteroseptal, and apical in the RVOT pacing group and in the apical, distal anteroseptal, inferoapical, distal anterior, and distal inferoseptal in the RVA pacing group. On univariate analysis, the incidence of perfusion defects was significantly associated with apical pacing, longer pQRS duration, and higher percentage of ventricular pacing. On multivariate analysis, the site of pacemaker insertion was found to be the most important pacemaker parameter determining the incidence of perfusion defects. Importantly, the duration of postpacemaker implantation did not show any significant relation to the incidence of perfusion defects. CONCLUSION: Fixed perfusion abnormalities are observed in patients with pacemakers and are independent of duration of time since implantation. RVOT pacing is associated with fewer incidences of myocardial perfusion abnormalities compared with RVA pacing.