Does Infarct Size Matter?

Steady Flow Left Ventricle Unloading Is Superior to Pulsatile Pressure Augmentation Venting During Venoarterial Extracorporeal Membrane Oxygenation Support

Venoarterial extracorporeal membrane oxygenation (VA-ECMO) shunts venous blood to the systemic arterial circulation to provide end-organ perfusion while increasing afterload that may impede left ventricle (LV) ejection and impair cardiac recovery. To maintain flow across the aortic valve and reduce risk of lethal clot formation, secondary mechanical circulatory support (MCS) devices are increasingly used despite limited understanding of their effects on cardiac function. This study sought to quantify the effects of VA-ECMO and combined with either intraaortic balloon pump (IABP) or percutaneous ventricular assist device (pVAD) on LV physiologic state and perfusion metrics in a porcine model of acute cardiogenic shock. Shock was induced through serial left anterior descending artery microbead embolization followed by initiation of VA-ECMO support and then placement of either IABP or pVAD. Hemodynamic measurements, LV pressure-volume loops, and carotid artery blood flow were evaluated before and after institution of combined MCS. The IABP decreased LV end-diastolic pressure by a peak of 15% while slightly increasing LV stroke work compared with decreases of more than 60% and 50% with the pVAD, respectively. The pVAD also demonstrated increased coronary perfusion and systemic pressure gradients in comparison to the IABP. Combined support with VA-ECMO and pVAD improves cardiovascular state in comparison to IABP.

Effect of tanshinone IIA for myocardial ischemia/reperfusion injury in animal model: preclinical evidence and possible mechanisms

Introduction: Tanshinone IIA (Tan IIA), the major active lipophilic ingredient of Radix Salviae Miltiorrhizae, exerts various therapeutic effects on the cardiovascular system. We aimed to identify the preclinical evidence and possible mechanisms of Tan IIA as a cardioprotective agent in the treatment of myocardial ischemia/reperfusion injury. Methods: The study quality scores of twenty-eight eligible studies and data analyses were separately assessed using the CAMARADES 10-item checklist and Rev-Man 5.3 software. Results: The study quality score ranged from 3/10 to 7/10 points. The present study provided preliminary preclinical evidence that Tan IIA could significantly decrease the myocardial infarct size, cardiac enzyme activity and troponin levels compared with those in the control group (p < 0.05). Discussion: Tan IIA alleviated myocardial I/R injury via antioxidant, anti-inflammatory, anti-apoptosis mechanisms and improved circulation and energy metabolism. Thus, Tan IIA is a promising cardioprotective agent for the treatment of myocardial ischemia/reperfusion injury and should be further investigated in clinical trials.

Effects of endovascular cooling on infarct size in ST-segment elevation myocardial infarction: A patient-level pooled analysis from randomized trials

OBJECTIVES

This study sought to examine the relationship between temperature at reperfusion and infarct size.

BACKGROUND

Hypothermia consistently reduces infarct size when administered prior to reperfusion in animal studies, however, clinical results have been inconsistent.

METHODS

We performed a patient-level pooled analysis from six randomized control trials of endovascular cooling during primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI) in 629 patients in which infarct size was assessed within 1 month after randomization by either single-photon emission computed tomography (SPECT) or cardiac magnetic resonance imaging (cMR).

RESULTS

In anterior infarct patients, after controlling for variability between studies, mean infarct size in controls was 21.3 (95%CI 17.4-25.3) and in patients with hypothermia <35°C it was 14.8 (95%CI 10.1-19.6), which was a statistically significant absolute reduction of 6.5%, or a 30% relative reduction in infarct size (P = 0.03). There was no significant difference in infarct size in anterior ≥35°C, or inferior infarct patients. There was no difference in the incidence of death, ventricular arrhythmias, or re-infarction due to stent thrombosis between hypothermia and control patients.

CONCLUSIONS

The present study, drawn from a patient-level pooled analysis of six randomized trials of endovascular cooling during primary PCI in STEMI, showed a significant reduction in infarct size in patients with anterior STEMI who were cooled to <35°C at the time of reperfusion. The results support the need for trials in patients with anterior STEMI using more powerful cooling devices to optimize the delivery of hypothermia prior to reperfusion.

Appropriate use of noninvasive ischemia testing to guide revascularization decision making following acute ST elevation myocardial infarction in Latin American countries: Results from an expert panel meeting of the International Atomic Energy Agency

Across Latin American and Caribbean countries, cardiovascular disease and especially ischemic heart disease is currently the main cause of death both in men and in women. For most Latin American and Caribbean countries, public and community health efforts aim to define care strategies which are both clinically and cost effective and promote primary and secondary prevention, resulting in improved patient outcomes. The optimal approach to deal with acute events such as ST-elevation myocardial infarction (STEMI) is a matter of controversy; however, there is an expanding role for assessing residual ischemic burden in STEMI patients following primary percutaneous coronary intervention. Although randomized clinical trials have established the value of staged fractional flow reserve-guided revascularization, the use of noninvasive functional imaging modalities may play a similar role at a much lower cost. For LAC, available stress imaging techniques could be applied to define residual ischemia in the non-infarct related artery and to target revascularization in a staged procedure after primary percutaneous coronary intervention The use of nuclear cardiac imaging, supported by its relatively wide availability, moderate cost, and robust quantitative capabilities, may serve to guide effective care and to reduce subsequent cardiac events in patients with coronary artery disease. This noninvasive approach may avert potential safety issues with repeat and lengthy invasive procedures, and serve as a baseline for subsequent follow-up stress testing following the index STEMI event. This consensus document was devised from an expert panel meeting of the International Atomic Energy Agency, highlighting available evidence with a focus on the utility of stress myocardial perfusion imaging in post-STEMI patients. The document could serve as guidance to the prudent and appropriate use of nuclear imaging for targeting therapeutic management and avoiding unnecessary invasive procedures within Latin American and Caribbean countries, where resources could be scarce.