Longitudinal strain in remote non-infarcted myocardium by tissue tracking CMR: characterization, dynamics, structural and prognostic implications.

Purpose: In ST-segment elevation myocardial infarction (STEMI) patients, longitudinal strain (LS) in remote non-infarcted myocardium (RNM) has not yet been characterized by tissue tracking (TT) cardiovascular magnetic resonance (CMR). In STEMI patients, we aimed to characterize RNM-LS by TT-CMR and to assess both its dynamics and its structural and prognostic implications.
Methods: We recruited 271 patients with a first STEMI studied with TT-CMR 1 week after infarction. Of these patients, 145 underwent 1-week and 6-month TT-CMR and were used to characterize both the dynamics and the short-term and long-term structural implications of RNM-LS. Based on previously validated data, RNM areas were defined depending on the culprit coronary artery.
Results: Reduced RNM-LS at 1 week (n = 70, 48%) was associated with larger infarct size and more depressed left ventricular ejection fraction (LVEF) at both the 1-week and 6-month TT-CMR (p value < 0.001). Late normalization of RNM-LS was frequent (28/70, 40%) and independently related to late recovery of LVEF (p value = 0.002). Patients with reduced RNM-LS at 1-week TT-CMR had more major adverse cardiac events (death, heart failure or re-infarction) in both the 271 patients included in the study group (26% vs. 11%, p value = 0.002) and in an external validation cohort made up of 177 STEMI patients (57% vs. 13%, p value < 0.001).
Conclusion: After STEMI, reduced RNM-LS by TT-CMR is common and is associated with more severe short- and long-term structural damage. There is a beneficial tendency towards recovery of RNM-LS that parallels late recovery of LVEF. More events occur in patients with reduced RNM-LS.