In this prospective study of consecutive patients aged ≤60 years presenting with unexplained AVB, we found that 11/32 (34%) had previously undiagnosed CS. Among patients with CS, 3/11 had adverse clinical outcomes compared with 0/21 (P = 0.011). Our data suggest that all patients aged ≤60 years with unexplained AVB should be investigated for CS. Moreover, patients diagnosed with CS should be closely followed.

Rubidium-ARMI ( 82 Rb as an Alternative Radiopharmaceutical for Myocardial Imaging) is a multicenter trial to evaluate the accuracy, outcomes, and cost-effectiveness of low-dose 82 Rb perfusion imaging using 3-dimensional (3D) PET/CT technology. Standardized imaging protocols are essential to ensure consistent interpretation. Methods: Cardiac phantom qualifying scans were obtained at 7 recruiting centers. Low-dose (10 MBq/kg) rest and pharmacologic stress 82 Rb PET scans were obtained in 25 patients at each site. Summed stress scores, summed rest scores, and summed difference scores (SSS, SRS, and SDS [respectively] 5 SSS-SRS) were evaluated using 17-segment visual interpretation with a discretized color map. All scans were coread at the core lab (University of Ottawa Heart Institute) to assess agreement of scoring, clinical diagnosis, and image quality. Scoring differences greater than 3 underwent a third review to improve consensus. Scoring agreement was evaluated with intraclass correlation coefficient (ICC-r), concordance of clinical interpretation, and image quality using k coefficient and percentage agreement. Patient 99m Tc and 201 Tl SPECT scans (n 5 25) from 2 centers were analyzed similarly for comparison to 82 Rb. Results: Qualifying scores of SSS 5 2, SDS 5 2, were achieved uniformly at all imaging sites on 9 different 3D PET/CT scanners. Patient scores showed good agreement between core and recruiting sites: ICC-r 5 0.92, 0.77 for SSS, SDS. Eighty-five and eighty-seven percent of SSS and SDS scores, respectively, had site-core differences of 3 or less. After consensus review, scoring agreement improved to ICC-r 5 0.97, 0.96 for SSS, SDS (P , 0.05). The agreement of normal versus abnormal (SSS $ 4) and nonischemic versus ischemic (SDS $ 2) studies was excellent: ICC-r 5 0.90 and 0.88. Overall interpretation showed excellent agreement, with a k 5 0.94. Image quality was perceived differently by the site versus core reviewers (90% vs. 76% good or better; P , 0.05). By comparison, scoring agreement of the SPECT scans was ICC-r 5 0.82, 0.72 for SSS, SDS. Seventy-six and eighty-eight percent of SSS and SDS scores, respectively, had site-core differences of 3 or less. Consensus review again improved scoring agreement to ICC-r 5 0.97, 0.90 for SSS, SDS (P , 0.05). Conclusion: 82 Rb myocardial perfusion imaging protocols were implemented with highly repeatable interpretation in centers using 3D PET/CT technology, through an effective standardization and quality assurance program. Site scoring of 82 Rb PET myocardial perfusion imaging scans was found to be in good agreement with core lab standards, suggesting that the data from these centers may be combined for analysis of the rubidium-ARMI endpoints.

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Patient driving behaviour following ICD implantation is variable, with over one-third not remembering and almost one-quarter not adhering to physician-directed driving restrictions. Over one-third of secondary ICD patients drive within 1 month despite physician recommendations. Further studies are required to establish the optimal duration of driving restriction in ICD recipients.