Patients with anterior ST-elevation myocardial infarction (STEMI) may benefit from the implementation of selective intracoronary hypothermia during primary percutaneous coronary intervention (PPCI), according to research results published in JACC: Cardiovascular Interventions.
Selective intracoronary hypothermia is a novel therapy that may reduce myocardial reperfusion injury in STEMI that has had demonstrated efficacy in animal model studies. In humans, only a small pilot study—SINTAMI (ClinicalTrials.gov Identifier: NCT02753478)—has been conducted and no clinical outcome data are no. Currently, the randomized controlled EURO-ICE trial (ClinicalTrials.gov Identifier: NCT03447834) is evaluating the effectiveness of selective intracoronary hypothermia to decrease infarct size.
In the current study, researchers evaluated the prespecified procedural safety in the first 50 patients with anterior STEMI in the EURO-ICE trial who were treated with selective intracoronary hypothermia during primary percutaneous coronary intervention (PPCI) vs the first 50 patients in the control group who received standard PPCI.
EURO-ICE includes adult patients between 18 and 80 years with anterior STEMI and summed ST-segment deviation on electrocardiogram of at least 5 mm. Patients were randomly assigned 1:1 to either the intervention or control group.
Patients were recruited between 2019 and 2021 in 6 European heart centers. Median age was 62.1 and 64.9 years in the intervention and control groups; 45 and 41 patients were men and median ∑ST-deviation was 16 vs 13 mm, respectively.
Culprit occlusion was in the proximal LAD (syntax segment 6) in 30 vs 26 patients, and in the mid LAD (syntax segment 7) in 20 vs 24 patients. Thrombolysis in myocardial infarction (TIMI) grade flow pre-PCI was grade 0 in 42 and 45 patients and grade 1 in 8 and 5 patients.
In the intervention group, symptom onset-to-balloon time was slightly shorter: 2 hours 23 minutes vs 2 hours 44 minutes. Door-to-balloon time, though, was slightly longer in this group: 30 vs 24 minutes, indicative of an additional 6 minutes needed for instrumentation required for the cooling procedure.
In the intervention group, target temperature was achieved in 104 seconds (interquartile range [IQR], 17-165) after infusion began; duration of the occlusion phase was 8 minutes (IQR, 7-10) and median intracoronary temperature was -6.47˚C (IQR, -6.00 to -7.00) vs baseline. Tympanically measured temperature fell by -0.20˚C (IQR, 0.00-0.60).
No heart rate change was noted during the occlusion phase and compared with baseline, mean arterial pressure (MAP) increased during the occlusion phase by 83 mmHg vs 92 mmHg, respectively.
Reperfusion duration was 10 minutes (IQR, 9-10). During this phase, intracoronary temperature was -6.44˚C vs baseline. Tympanic temperature changed by -0.10˚C. Heart rate did not change, but MAP slightly increased vs baseline.
In 15 patients in whom a CoolCell® catheter was used, door-to-balloon time was shorter (27 minutes vs 32 minutes for over the wire balloon).
All patients survived to hospital discharge. Five and 3 patients in each group experienced ventricular fibrillation (VF) requiring defibrillation at some point during the procedure. In the intervention group, 1 patient experienced before saline infusion began; 2 patients had VF during the occlusion phase, 1 had VF during the reperfusion phase, and 1 had VF 10 minutes after the intervention was completed. In the control group, 2 patients experienced VF before and 1 had VF directly after reperfusion.
No reports of peripheral embolization have been made, and no procedures were complicated by air emboli. Post-PCI TIMI grade flow 2 or 3 was noted in 50 vs 47 patients in the intervention and control groups, while stent thrombosis was observed in 2 and 0 patients, respectively.
Across both groups, 1 patient developed acute heart failure requiring the use of intravenous diuretics and vasopressive agents. One patient in the intervention group required extracorporeal membrane oxygenation (ECMO) support as a “bridge to recovery”; this patient was weaned successfully from ECMO after 1 week.
Study limitations include a lack of outcome data due to the nature of the exploratory safety analysis, the potential for bias due to the small study sample size, and the inclusion only of patients with anterior STEMI and proximal or mid left anterior descending occlusion.
“This first report on the safety of selective intracoronary hypothermia…suggests that the procedure can be implemented safety during primary PIC without increased risk of complications,” the researchers concluded. “The ongoing randomized controlled EURO-ICE study will demonstrate whether selective intracoronary hypothermia will reduce [infarct size] and improve clinical outcome.”
Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
El Farissi M, Good R, Engstrøm T, et al. Safety of selective intracoronary hypothermia during primary percutaneous coronary intervention in patients with anterior STEMI. JACC: Cardiovasc Interv. Published online August 17, 2021. doi:10.1016/j.jcin.2021.06.009