Myocardial flow reserve recovery in patients with Takotsubo syndrome: insights from positron emission tomography

Coronary microvascular dysfunction (CMD) has been implicated in the pathogenesis of Takotsubo syndrome (TTS). Positron emission tomography (PET) plays a key role in the assessment of CMD through myocardial flow reserve (MFR). However, there is limited information on the temporal progression of MFR and its relationship to coronary artery disease (CAD) in TTS patients.

This study evaluated patients with TTS who underwent cardiac catheterization and PET within one year of hospitalization. Patients were categorized into acute (≤10 days), subacute (11-30 days), and chronic (≥31 days) stages based on post-onset time of PET assessment. MFR comparisons between stages, prevalence of abnormal MFR (<2.0), and MFR changes with or without obstructive CAD (≥70% stenosis as per coronary angiography) were analyzed.

Of the 88 patients studied (mean age 70; 96% female), 52 (59%) were in the acute, 17 (19%) in the subacute, and 19 (22%) in the chronic stage. Median MFR in the acute stage was 2.0 (1.5-2.3), with 58% of patients showing abnormal MFR. A significant time-dependent improvement in MFR was observed (p=0.002) (Figure A), accompanied by a decreased prevalence of abnormal MFR. Patients with obstructive CAD in the acute stage had a significantly lower MFR compared to patients without CAD (1.81 vs. 2.15, p=0.027), while no MFR improvement was observed in the subacute and chronic stages (p=0.346) (Figure B).

PET-derived MFR was impaired in TTS patients during the acute phase, with improvement suggesting potential recovery from CMD over time. The concurrent presence of obstructive CAD might impede this recovery process.  Figure B