1356611 - Myocardial Strain Impacts of Hypothermia as an Adjunctive Therapy to Percutaneous Intervention after ST-elevation Myocardial Infarction - Randomized Trial

The role of endovascular therapeutic hypothermia (ETH) is still controversial in ST-elevation myocardial infarction (STEMI) and its impact on segmental contractility has still not been evaluated. Our study aims to investigate whether ETH as adjunctive therapy to percutaneous coronary intervention (PCI) has implications for myocardial strains.

Methods: We included 40 patients with acute anterior or inferior STEMI randomized to receive ETH, who underwent 1.5T cardiac magnetic resonance (CMR) at 5 and 30 days after STEMI. We excluded patients with previous acute MI and recent stroke. Circumferential (Circ) and radial (Rad) strains were measured (feature tissue-tracking by CVI42 - Circle Cardiovascular Imaging) on cine-MR LV short axes, each one divided in 12 segments (5210 in total), and labeled as infarcted, adjacent, and remote from infarcted myocardium, based on late gadolinium enhancement (LGE). Repeated measures of ANOVA were used to compare strains with time and treatment, accounting for non-independence in segments within each patient.

Results: Hypothermia (H, primary PCI+ETH, n=29, 53±10 years) and control (C, primary PCI, n=11, 58±8 years) groups had no differences in sex, global volume parameters, infarct area and ejection fraction. From 5 to 30 days after STEMI, infarcted areas in the H group showed higher increase in Rad (11.2±16 vs 14.8±15.2, p=0.001) and Circ (-5.4±11.1 vs -8±11.1, p=0.001) strains, compared to C group (Rad: 11.4±14 vs 13.1±16.8, p=0.09; Circ: -6.5±10.6 vs -6.4±12.5, p=0.94). Rad and Circ strains were higher at 30 days in the H group (14.8±15.2 vs 13.1±16.8, p=0.01; -8±11.1 vs -6.4±12.5, p=0.01; respectively). Remote areas in the C group had a greater increase from 5 to 30 days in Rad (28±18 vs 31.7±18.5, p=0.001) and Circ (-15.5±10.7 vs -17.1±9, p=0.001) strains, compared to the H group (28.6±18.6 vs 29±20, p=0.44; -15.2±10.4 vs -15.3±10.6, p =0.82). Rad and Circ strains were higher at 30 days in the C (31.7±18.5 vs 29±20, p=0.001; -17.1±9 vs -15.3±10.6, p=0.001). Non-viable infarcted areas (LGE >50%) in H group had higher Rad (11.8±13.2 vs 8.17±14.7, p=0.001) and Circ (-6.1±10.9 vs -3.1±11.3, p=0.001) strain increase compared to C, with higher values at 30 days (Rad: 11.8±13.2 vs 8.9±16.3, p=0.003; Circ: -6.1±10.9 vs -3.3±12.9, p=0.001), compared to the C group. There was no decline of contractility in any case.

Conclusion: In patients with anterior and inferior STEMI, ETH adjuvant to PCI is associated with significant increase in radial and circumferential strains of the infarcted area, even in non-viable infarcted areas, but not in the remote area. This finding may be related to the lower need for myocardial compensatory contractility recruitment in the remote area, since hypothermia patients recovered more contractility in the infarcted area. Further larger studies are needed to confirm these findings.