The clinical challenge of preventing sudden cardiac death immediately after acute ST-elevation myocardial infarction

Thrombus aspiration catheter improve the myocardial reperfusion of STEMI patients with high thrombus load during the emergency PCI operation

OBJECTIVE

This study aims to discuss the efficacy and safety of the application of thrombus aspiration catheters during emergency PCI operations for acute ST-elevation myocardial infarction (STEMI) patients with high thrombus load.

METHODS

A total of 204 patients diagnosed with acute STEMI and high thrombus load in the Sixth Affiliated Hospital of Guangxi Medical University from July 1, 2016 to June 30, 2017 were selected for the present study. These patients were randomly divided into two groups: thrombus catheter aspiration group (group A, n = 101), and balloon dilatation group (group B, n = 103). The blood flow of the culprit coronary artery in the thrombolysis in myocardial infarction (TIMI) immediately after the emergency PCI operation in these two groups of patients was recorded. Then, an echocardiogram was performed to determine the left ventricular end-diastolic diameter (LVEDD) and left ventricular ejection fraction (LVEF) after the operation, and data on major adverse cardiovascular events (MACE) during the 30 days of postoperative follow-up were collected.

RESULTS

The comparative difference between these two groups of patients in terms of hypertension, smoking, diabetes, usage rate of GPIIb/IIIa receptor antagonist, time from hospitalization to balloon dilatation (D2B) and other basic clinical data was not statistically significant (P > 0.05). The postoperative TIMI flow grade of these two groups of patients improved, and the comparative difference between the data obtained from these two groups was statistically significant (P < 0.05). The comparative difference between these two groups in terms of LVEDD and LVEF at 7 days after the operation was not statistically significant (P > 0.05). There was a difference in the occurrence rate of MACE in these two groups of patients during the 30 days of postoperative follow-up, but the comparative difference between these two groups was not statistically significant (P = 0.335).

CONCLUSION

The application of thrombus aspiration catheter during the emergency PCI operation of STEMI patients with high thrombus load can better improve the myocardial reperfusion. There is no basis for increasing the stroke occurrence risk. However, it obviously fails to improve the recent prognosis and more studies need to explore its effect on myocardial remodeling and major adverse cardiovascular events.

The Role of the Cardioversion Defibrillator in Post Myocardial Infarction Sudden Cardiac Death: A Systematic Review of Clinical Trials and Observational Studies

Sudden cardiac death (SCD) accounts for approximately half of all the deaths attributed to cardiovascular disease in the United States. Survivors of an acute myocardial infarction (AMI) are at high risk of SCD, largely due to cardiac arrhythmias and severe left ventricular (LV) systolic dysfunction. The implantable cardioverter defibrillator (ICD) or automated implantable cardioverter defibrillator (AICD) is a device that is implantable inside the body, able to perform cardioversion, defibrillation, and (in modern versions) pacing of the heart. According to a study included in our review, patients who received an ICD contributed to an adjusted 44% reduction (hazard ratio [HR] 0.56, 95% CI: 0.32-1.01; P = 0.053) of all-cause mortality compared to those with a comparable baseline. Patients with an ICD implant three months after a myocardial infarction (MI) demonstrated a non-significantly higher mortality than patients who did not receive an ICD. The factors favoring ICD implantation were multiple MIs, increased resting heart rate, occurrence of non-sustained ventricular tachycardia, QRS duration = 120 ms, syncope events, anti-arrhythmic drug treatment (mostly Class III), and an index MI of more than one year. The likelihood of receiving an ICD diminished with the patient's age. Increased periodic repolarization dynamics were a significant predictor of mortality. It can be concluded that cardioverter defibrillators help reduce not only all-cause mortality but also sudden cardiac death. It is important to note that ICDs are only significant if implanted after a sufficient time-gap post-MI.

Pharmacologic inhibition of the mitochondrial Na+/Ca2+ exchanger protects against ventricular arrhythmias in a porcine model of ischemia-reperfusion

BACKGROUND

The mitochondrial Na+/Ca2+ exchanger (mNCX) has been implicated in the pathogenesis of arrhythmogenicity and myocardial reperfusion injury, rendering its inhibition a potential therapeutic strategy. We examined the effects of CGP-37157, a selective mNCX inhibitor, on arrhythmogenesis, infarct size (IS), and no reflow area (NRA) in a porcine model of ischemia-reperfusion.

METHODS

Forty pigs underwent myocardial ischemia for 60 minutes, followed by 2 hours of reperfusion. Animals were randomized to receive intracoronary infusion of 0.02 mg/kg CGP-37157 or vehicle, either before ischemia (n=17) or before reperfusion (n=17). Animals were monitored for arrhythmias. Myocardial area at risk (AR), IS, and NRA were measured by histopathology.

RESULTS

AR, NRA, and IS were comparable between groups. Administration of CGP-37157 before ischemia resulted in the following: (a) suppression of ventricular tachyarrhythmias (events/pig: 1.5±1.1 vs 3.5±1.9, p=0.014), (b) easier cardioversion of ventricular tachyarrhythmias (defibrillations required for cardioversion of each episode: 2.6±2.3 vs 6.2±2.1, p=0.006), and (c) decreased maximal depression of the J point (0.75±0.27 mm vs 1.75±0.82 mm, p=0.007), compared to controls. Administration of CGP-37157 before reperfusion expedited ST-segment resolution; complete ST-segment resolution within 30 minutes of reperfusion was observed in 7/8 CGP-37157-treated animals versus 1/9 controls (p=0.003).

CONCLUSIONS

In a porcine model of myocardial infarction, intracoronary administration of CGP-37157 did not decrease IS or NRA. However, it suppressed ventricular arrhythmias, decreased depression of the J point during ischemia and expedited ST-segment resolution after reperfusion. These findings motivate further investigation of pharmacologic mNCX inhibition as a potential therapeutic strategy to suppress arrhythmias in the injured heart.