The efficacy and safety of ECG-gated dipyridamole MPI in patients with aortic stenosis using a CZT camera

1561 Objectives: Aortic stenosis (AS) is the most valvular disorder, and concomitant coronary artery disease (CAD) is rather common. The role of vasodilator myocardial perfusion imaging (MPI) in the patients with significant AS is still controversial due to safety concerns and unclear clinical accuracy. In addition, the utility to detect myocardial ischemia in patients after aortic valve (AV) intervention has not been established. The purpose of this study is to evaluate the efficacy and safety of MPI in patients with AS and after AV intervention. Methods: Patients, who underwent ECG-gated dipyridamole MPI using a CZT camera between 2015 and 2016, with AS based on echocardiography within 6 months were retrospectively reviewed (n=102) and divided into 3 groups: (1) mild AS, (2) moderate-to-severe AS, and (3) prior AV intervention (post-intervention day, median=2,897, range=350-11,014). Patients with angiographically documented CAD (≧50% stenosis) (n=36), severe arrhythmia (n=9), left ventricular ejection fraction (LVEF)UCG<40% (n=4), left bundle branch block (n=3) or no follow-up after MPI (n=3) were excluded. Summed stress and rest scores (SSS, SRS) were derived from a 0 (normal) to 4 (absent uptake) score system and 17-segment model. Lung/heart ratio (LHR) and volumetric data using QGS analysis were also calculated. The relationships between severity of AS and clinical characteristics, hemodynamic response, serious adverse events and MPI parameters were compared between groups. All variables were processed with appropriate analytic methods. Results: A total of 47 patients were included for analysis. None had serious adverse effects, including significant hypotension and LVEF reduction after stress. In addition, no differences of adverse events between groups except marginally more hot flush in patients with moderate to severe AS (p=0.05) were noted. Comparing to patients with mild AS, patients with moderate to severe AS had significantly higher SSS and lower LVEF (p<0.05). On the contrary, there was no statistical difference in SSS, SRS and LVEF between patients with moderate-severe AS and after AV intervention. SSS was positively correlated with male gender, AV mean pressure gradient (PG), post-stress LHR, and post-stress end-diastolic volume (EDVs) (p<0.05). After multivariate analysis, post-stress LHR and EDVs were the independent contributors to SSS. SRS was positively correlated with male gender, AV mean PG, post-stress LHR (p<0.05) but not EDVs, and only post-stress LHR was the independent predictor of SRS after multivariate analysis. Conclusions: In this AS cohort, there was no serious adverse event, significant hypotension or LVEF reduction during vasodilator stress, except a trend of more hot flush in patients with moderate to severe AS. Vasodilator-induced ischemia and LV dysfunction using ECG-gated MPI may result from microvascular dysfunction in patients with moderate to severe AS in absence of obstructive CAD. In addition, the abnormalities might continue after AV intervention. These findings support that MPI provides additional prognostic information in such patients.