Global Microvascular Dysfunction and Incomplete Recovery in Takotsubo Syndrome: Insights From Serial PET Imaging

BACKGROUND: The proposed cause of Takotsubo syndrome (TTS) includes coronary microvascular dysfunction. This study aimed to investigate coronary microvascular dysfunction and its recovery in patients with TTS using serial positron emission tomography myocardial perfusion imaging. METHODS: Patients with TTS who underwent cardiac positron emission tomography within 30 days of admission and at 6-month follow-up (May 2017–June 2023) were analyzed. Changes in positron emission tomography parameters, including extent of myocardial perfusion abnormality, left ventricular function, rest and stress myocardial blood flow (MBF), myocardial flow reserve, and coronary vascular resistance (CVR), were assessed from baseline to follow-up. In apical TTS, segmental analyses (basal, mid, distal segments, and apex) and intersegment differences were evaluated. RESULTS: Of 130 patients screened, 62 patients (median age, 70 years, 97% female) were included. After a median follow-up of 178 (121–282) days, global rest and stress MBF, myocardial flow reserve, and CVR significantly improved at follow-up (0.81–0.89 mL/min per gram, P =0.004; 1.56–2.61 mL/min per gram, P <0.001; 1.96–2.65, P <0.001; 52.0–36.2 mm Hg·min·g/mL, P <0.001, respectively). Among 53 patients with apical TTS, improvements in stress MBF, myocardial flow reserve, and CVR were noted in all myocardial segments (all P <0.001), including the basal segment; however, persistent MBF and CVR abnormalities were identified in the distal segment and apex, despite full recovery of left ventricular function. CONCLUSIONS: Patients who underwent serial positron emission tomography perfusion imaging for TTS demonstrated reversible reductions in rest and stress MBF, myocardial flow reserve, and increases in CVR, suggestive of TTS-related coronary microvascular dysfunction and subsequent subtotal recovery. Coronary microvascular dysfunction extended beyond regions of wall motion abnormalities, and regional coronary flow abnormalities persisted in the medium term even after recovery of left ventricular function.