Myocardial Blood Flow Quantification in Patients with an Implanted Cardiodefibrillator during Stress and at Rest using a Wideband Perfusion Pulse Sequence: An Initial Feasibility Study.

Background: Although a recently developed wideband perfusion sequence has shown diagnostically acceptable image quality and accurate myocardial blood flow (MBF) quantification at rest in patients with cardiac implanted electronic devices (CIEDs), its performance during vasodilator stress remains unproven. This study aims to determine whether the sequence produces diagnostically acceptable image quality during stress and is capable of quantitatively detecting abnormal stress MBF and myocardial perfusion reserve (MPR) in patients with implanted cardiodefibrillators (ICDs).

Methods: We enrolled 29 patients with an ICD (mean age = 63 ± 15 years, 17 males, 12 females) and 11 control patients (mean age = 50 ± 17 years, 6 males, 5 females; negative coronary artery disease; negative stress perfusion CMR; and no cardiac event one year post CMR) with an ICD taped below the left clavicle to mimic image artifacts. Both groups underwent imaging using a six-fold accelerated wideband perfusion sequence during adenosine stress and at rest. Images were reconstructed using a compressed sensing framework. Two clinical readers independently graded the following three categories on a 5-point Likert scale (1: worst, 3: clinically acceptable, 5: best): conspicuity of wall enhancement, noise, and artifact. Pixel-wise stress-rest MBF maps were quantified for both global and segmental analysis. MPR was calculated as the ratio of mean stress to rest MBFs.

Results: The median summed visual score was above the acceptable cut-point (>9.0) and not significantly different between the two groups. Both mean global and segmental stress MBF and MPR were significantly lower (p < 0.05) in the ICD patient group (global MBF=1.79±0.50ml/g/min; global MPR=2.11±0.53) compared to the control group (global MBF=2.92±0.52ml/g/min; global MPR=3.28±0.57), while rest MBF showed no significant difference (global MBF=0.88±0.18ml/g/min in the patient group vs. 0.92±0.13ml/g/min in the control group).

Conclusions: This study demonstrates the feasibility of using a six-fold accelerated wideband perfusion pulse sequence, which provides diagnostically acceptable image quality during stress and is sensitive for detecting abnormal stress MBF and MPR in patients with ICDs.