Key result
In patients with Takotsubo syndrome, angiography-derived index of microvascular resistance in the left anterior descending artery was significantly higher in those with left ventricular ejection fraction ≤40% compared to those with preserved function (59.3 vs 46.3, p=0.030).
Why the study?
Coronary microvascular dysfunction (CMD) is proposed as a key driver in Takotsubo syndrome (TTS), but assessment using angiography-derived index of microcirculatory resistance (IMR) and its correlation with clinical presentation required evaluation.
Observational (n=41)
No
Absolute Event Rate: 59.3% vs 46.3%
p-value: p=0.030
Angiography-derived IMR reveals that coronary microvascular dysfunction is universally present in Takotsubo syndrome and inversely correlates with left ventricular systolic function.
CMD assessment via IMR in TTS is hypothesis-generating; prospective validation needed before clinical adoption.
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.
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Castaldi et al. (2022) conducted an observational in Takotsubo syndrome (n=41). Left ventricular ejection fraction impairment (≤ 40%) vs. Preserved left ventricular ejection fraction (> 40%) was evaluated on Angiography-derived index of microvascular resistance (NH-IMRangio) in the left anterior descending artery (p=0.030). In patients with Takotsubo syndrome, angiography-derived index of microvascular resistance in the left anterior descending artery was significantly higher in those with left ventricular ejection fraction ≤40% compared to those with preserved function (59.3 vs 46.3, p=0.030).
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