Impact of the dynamics of ejection fraction on risk stratification in a large multicenter registry of STEMI patients using sequential CMR
Authors: Marcos Garces V , Gavara J , Lopez-Lereu M.P , Monmeneu J.V , Rios-Navarro C , De Dios E , Merenciano-Gonzalez H , Gabaldon-Perez A , Bonanad C , Chorro F.J , Valente F , Lorenzatti D , Rodriguez-Palomares J.F , Ortiz J.T , Bodi V 
Published: November 2020

Abstract

Background
Left ventricular ejection fraction (LVEF) has traditionally been used as the cornerstone for risk stratification after ST-segment elevation myocardial infarction (STEMI) and it can be accurately quantified by cine cardiovascular magnetic resonance (CMR). In recent years, the additional prognostic value of contrast CMR-derived infarct size (IS) and microvascular obstruction (MVO) has been demonstrated.

Purpose
We explored the impact of sequential assessment of CMR-derived LVEF on dynamic risk stratification after STEMI.

Methods
Data were obtained from three prospective registries of reperfused STEMI patients (n=1036) in whom LVEF, IS and MVO were sequentially quantified by CMR (at least at 1 week and at 6 months). Major adverse cardiac events (MACE) were defined as a combined clinical end-point: death or re-admission for acute heart failure (HF), whichever occurred first. Late events were regarded as those occurring after the 6-month CMR.

Results
During a mean and median follow-up of 5 years, 105 first MACE (10%, 36 deaths and 69 HF) and 82 late MACE (8%, 35 deaths and 47 HF) were registered. From 1-week to 6-month CMR, LVEF improved (49±12 vs. 53±12%), IS decreased (21±14 vs 17±12% of LV mass) and MVO vanished (1.3±1.9 vs. 0.1±0.7% of LV mass), p&lt;0.001 for all comparisons. At 1-week CMR, 207 patients (20%) displayed reduced LVEF (r-LVEF, &lt;40%), 328 (32%) mid-range LVEF (mr-LVEF, 40–50%) and 501 (48%) preserved LVEF (p-LVEF, &gt;50%). At 6-month CMR, 144 patients (14%) displayed r-LVEF, 247 (24%) mr-LVEF and 645 (62%) p-LVEF. The total MACE rate was higher (p&lt;0.001) only in patients with r-LVEF at 1 week (22%) vs. 7% in those with mr-LVEF and 7% in those with p-LVEF. Similarly, the late MACE rate was higher (p&lt;0.001) only in patients with r-LVEF at 6 months (20%) vs. 7% in those with mr-LVEF and 5% in those with p-LVEF. The late MACE rate was very low in patients with sustained mr- or p-LVEF (41/794, 5%), intermediate in those with improved LVEF from r-LVEF at 1 week to mr- or p-LVEF at 6 months (12/98, 12%) and high in patients with sustained r-LVEF (22/109, 20%) or worsened LVEF from mr- or p-LVEF at 1 week to r-LVEF at 6 months (7/35, 20%), p&lt;0.001 for the trend. Using a Markov approach, only r-LVEF (at any time assessed) significantly related to a higher MACE rate.

Conclusions
Of available CMR parameters, LVEF persists as the pivotal index for simple post-STEMI risk stratification. Mid-range or preserved LVEF in acute phase associates with excellent long-term outcome. Changes in LVEF provide valuable dynamic prognostic information. Maintenance of mid-range or preserved LVEF in chronic phase occurs in the majority of patients and associates with a very low risk of late clinical events. Whereas late improvement reaching at least mid-range LVEF exerts salutary effects, detection of reduced LVEF at this point identifies the small subset of patients at high risk in the long term.
Figure 1

Funding Acknowledgement
Type of funding source: Public grant(s) – National budget only. Main funding source(s): This study was funded by “Instituto de Salud Carlos III” and “Fondos Europeos de Desarrollo Regional FEDER” (PIE15/00013, PI17/01836, and CIBERCV16/11/00486 grants).