J Cardiovasc Imaging.  2018 Sep;26(3):175-185. 10.4250/jcvi.2018.26.e21.

Impact of Natural Mild Hypothermia in the Early Phase of ST-Elevation Myocardial Infarction: Cardiac Magnetic Resonance Imaging Study

• Lim K
• Yang JH
• Hahn JY
• Choi SH
• Gwon HC
• Park SJ
• Song YB

• KMID: 2429859
• DOI: http://doi.org/10.4250/jcvi.2018.26.e21

Abstract

BACKGROUND
Mild hypothermia (32-35°C) during acute myocardial ischemia has been considered cardioprotective in animal studies. We sought to determine the association of between natural mild hypothermia and myocardial salvage as assessed by cardiac magnetic resonance imaging (CMR) in ST-elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (PCI).
METHODS
In 291 patients with STEMI, CMR was performed a median of 3 days after the index event. Body temperature was collected for 24 hours after PCI. Fifty-one patients (17.5%) had natural mild hypothermia (less than 35°C) during the day after PCI, and 240 (82.5%) did not.
RESULTS
The primary endpoint, the myocardial salvage index, was significantly higher in the natural mild hypothermia group than in the normothermia group (median [IQR], 50 [37-64] vs. 43 [30-56], p = 0.013). The myocardial area at risk between the 2 groups did not differ (39 [22-51] vs. 35 [24-44], p = 0.361), nor did the infarct size (16 [10-28] vs. 20 [12-27], p = 0.301), presence of microvascular obstruction (57% vs. 60%, p=0.641), or hemorrhagic infarction (43% vs. 46%, p = 0.760). A multivariable linear regression showed a significant association between the lowest body temperature and myocardial salvage index (β = -0.191, p = 0.001).
CONCLUSIONS
In patients with STEMI undergoing primary PCI, natural mild hypothermia within 24 hours is associated with greater salvaged myocardium.

Keyword

Natural mild hypothermia; ST-elevation myocardial infarction; Percutaneous coronary intervention; Cardiac magnetic resonance imaging

MeSH Terms

Animals
Body Temperature
Humans
Hypothermia*
Infarction
Linear Models
Magnetic Resonance Imaging*
Myocardial Infarction*
Myocardial Ischemia
Myocardium
Percutaneous Coronary Intervention

Figure

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  Figure 1 A schematic diagram of study patents selection. BT: body temperature, MI: myocardial infarction, PCI: percutaneous coronary intervention, STEMI: ST-segment elevation myocardial infarction.

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  Figure 2 Example CMR images of anterior STEMI underwent PCI. Short-axis slices of T2-weighted image (A) and the corresponding delayed hyperenhancement image (B) in patients with anterior STEMI. The extent of area at risk (C) and infarct size (D) are the area surrounded by dot lines and indicated by white arrow. CMR: cardiac magnetic resonance imaging, PCI: percutaneous coronary intervention, STEMI: ST-segment elevation myocardial infarction.

• 

  Figure 3 Boxplots of CMR findings according to the presence of mild hypothermia and MSI (A), IS (% of LV) (B), extent of AAR (% of LV) (C). AAR: area at risk, CMR: cardiac magnetic resonance imaging, IS: infarct size, LV: left ventricle, MSI: myocardial salvage index.

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  Figure 4 The relationship between MSI and body temperature in patients with STEMI. MSI: myocardial salvage index, STEMI: ST-segment elevation myocardial infarction.

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  Figure 5 The median value of body temperature measured during 24 hours. The blue solid line indicates the normothermia group. The brown dotted line indicate mild hypothermia group. PCI: percutaneous coronary intervention.

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