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. 2023 Jan;39(1):233-244.
doi: 10.1007/s10554-022-02698-6. Epub 2022 Nov 7.

Angiography-derived index of microvascular resistance in takotsubo syndrome

Gianluca Castaldi #  1 , Simone Fezzi #  1 , Maddalena Widmann #  1 , Micaela Lia  1 , Francesca Rizzetto  1 , Concetta Mammone  1 , Sara Pazzi  1 , Solange Piccolo  1 , Verdiana Galli  1 , Michele Pighi  1 , Gabriele Pesarini  1 , Daniele Prati  1 , Valeria Ferrero  1 , Roberto Scarsini  1 , Domenico Tavella  1 , Flavio Ribichini  2
Affiliations

Angiography-derived index of microvascular resistance in takotsubo syndrome

Gianluca Castaldi et al. Int J Cardiovasc Imaging. 2023 Jan.

Abstract

Coronary microvascular dysfunction (CMD) has been proposed as a key driver in the etiopathogenesis of Takotsubo syndrome (TTS), likely related to an "adrenergic storm" upon a susceptible microvascular circulation. The aim of our manuscript was to assess CMD in patients with TTS through the computation of the angiography-derived index of microcirculatory resistance (IMR) and its correlation with clinical presentation. Coronary angiograms of 41 consecutive TTS patients were retrospectively analyzed to derive angiography-based indices of CMD. Three indices (NH-IMRangio, AngioIMR and A-IMR) were calculated based on quantitative flow ratio. CMD was defined as an IMRangio value ≥ 25 units. The correlation between CMD and clinical presentation was then assessed. Median age was 76 years, 85.7% were women and mean left ventricular ejection fraction (LVEF) at first echocardiogram was 41.2%. Angiography-derived IMR was higher in left anterior descending artery (LAD) than circumflex and right coronary artery with either NH-IMRangio (53.9 ± 19.8 vs 35.8 ± 15.4 vs 40.8 ± 18.5, p-value < 0.001), AngioIMR (47.2 ± 17.3 vs 31.8 ± 12.2 vs 37.3 ± 13.7, p-value < 0.001) or A-IMR (52.7 ± 19 vs 36.1 ± 14.1 vs 41.8 ± 16.1, p-value < 0.001). All patients presented CMD with angiography-derived IMR ≥ 25 in at least one territory with each formula. Angiography-derived IMR in LAD territory was significantly higher in patients presenting with LVEF impairment (≤ 40%) than in those with preserved ventricular global function (NH-IMRangio: 59.3 ± 18.1 vs 46.3 ± 16.0 p-value = 0.030; AngioIMR: 52.9 ± 17.8 vs 41.4 ± 14.2, p-value = 0.037; A-IMR: 59.2 ± 18.6 vs 46.3 ± 17.0, p-value = 0.035). CMD assessed with angiography-derived IMR is a common finding in TTS and it is inversely correlated with LV function. The available formulas have a substantial superimposable diagnostic performance in assessing coronary microvascular function.

Keywords: Coronary physiology; Index of microvascular resistance; Quantitative flow ratio; Takotsubo syndrome.

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Conflict of interest statement

The authors declare no competing interests.

The authors declare that no funds, grants, or other support were received during the preparation of this manuscript. The authors have no relevant financial or non-financial interests to disclose.

Figures

Fig. 1
Fig. 1
Step-by-step angiography-derived IMR computation from QFR. Firstly, 2D-QCA analysis of target vessel is performed; secondly, 3D-QCA model simulation is automatically derived and vessel QFR is computed by the software. Finally, IMR according to the respective formulas is calculated, cQFR contrast-QFR; fps frame per second; IMR index of microvascular resistance; LAD left anterior descending; LCX left circumflex; N number; Pa arterial pressure; QFR quantitative flow ratio; RCA right coronary artery
Fig. 2
Fig. 2
Correlation of angiography-derived IMR in the LAD territory with the three different formulas and LVEF (A) and TnxURL (C); correlation of global IMR MEAN according to three formulas and LVEF (B). IMR index of microvascular resistance; LAD left anterior descending; LCX left circumflex; LVEF left ventricular ejection fraction; RCA right coronary artery; TnxURL high-sensitivity troponin upper reference limit
Fig. 3
Fig. 3
Scatter plot of angiography-derived IMR for each main epicardial vessel (LAD, LCX, RCA) and mean global value with each formula (NH-IMRangio, AngioIMR, A-IMR). IMR: index of microvascular resistance; LAD left anterior descending; LCX left circumflex; RCA right coronary artery
Fig. 4
Fig. 4
Bland–Altman plot analysis (difference vs average) of the agreement between the three formulas. IMR index of microvascular resistance
Fig. 5
Fig. 5
Multiparametric and multimodality approach to TTS. CMD coronary microvascular disfunction; IMR index of microvascular resistance; LGE late gadolinium enhancement; LVEF left ventricular ejection fraction
See this image and copyright information in PMC

Comment in

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