Independent prognostic value of left ventricular stroke volume index in patients with takotsubo syndrome: insights from the EVOLUTION registry

Background Prognostic relevance of cardiac magnetic resonance (CMR) in takotsubo syndrome (TTS) is not fully elucidated. We aimed to assess the prognostic value of CMR-derived left ventricular stroke volume indexed (LVSVi) in patients with TTS. Methods Consecutive patients with TTS underwent CMR at median 5 days (3–7) after admission. CMR analysis was centralised, patients were categorised by LVSVi (<35 vs ≥35 mL/m²). Median follow-up was 360 days. Primary endpoint was a composite of major adverse cardiovascular events and all-cause-death, secondary endpoint was all-cause-death. Results This observational study included 376 patients (mean age 70±11 years; 9% male). Average left ventricular ejection fraction (LVEF) on admission was 43%, increasing to 48% at CMR imaging. 172 (46%) patients had CMR-derived LVSVi <35 mL/m²; these were older and showed higher prevalence of hypertension and dyspnoea and a lower LVEF at admission. On CMR, low LVSVi patients demonstrated smaller LV end-diastolic volumes, lower biventricular systolic function and larger myocardial oedema. Kaplan-Meier analyses showed higher primary and secondary endpoint rates in the low-LVSVi group (both log-rank p<0.01) and lowest event rates in patients having both high LVSVi and normal LVEF (both log-rank p<0.01). Multivariable Cox-regression analysis identified LVSVi as an independent predictor of both the primary (HR 0.96; 95% CI 0.92 to 0.98) and secondary (HR 0.95; 95% CI 0.90 to 0.99) endpoint. Conclusions Early CMR after admission in patients with TTS highlights recovering LVEF with relatively low LVSVi. Low LVSVi independently predicted mid-term outcomes, and the presence of both high LVSVi and recovered LVEF identified a low-risk subgroup.