Prognostic Impact of Acute Myocardial Infarction-Related Ventricular Tachyarrhythmia in the Current Era　― Reply ―

We thank Drs Kataoka and Imamura for their interest in our study.¹ As suggested, management for patients with acute myocardial infarction (AMI) has been advanced by introducing left ventricular (LV) mechanical circulatory support devices, such as Impella, catheter ablation for refractory sustained ventricular tachycardia (VT) and ventricular fibrillation (VF),^2–4 newly developed pharmacological agents, and appropriate indication of implantable cardioverter defibrillators (ICD).⁵

Cardiogenic shock, caused by a broad area of myocardial ischemia/infarction due to severe multivessel or left main trunk disease, is the most common cause of death in AMI patients with VT/VF, especially when VT/VF occurs after primary percutaneous coronary intervention (PCI).¹ Impella has been applied to patients with cardiogenic shock to provide hemodynamic stability and the expectation of salvaging myocardium and preserving LV function via LV unloading. As noted, Impella reduced infarct size via suppression of myocardial oxygen consumption in an animal model.⁶ However, because half of Impella recipients are reported to die within 30 days of implantation in real-world clinical practice, it is still controversial whether Impella can reduce death from AMI complicated with cardiogenic shock.^7,8

VT/VF occurring in the acute phase of AMI is sometimes refractory even under appropriate use of anti-arrhythmic agents, and therefore multiple sources of support (i.e., cardioversion/defibrillation and extracorporeal membrane oxygenation) are required.¹ Recently, involvement of the Purkinje network in refractory VT/VF and the usefulness of catheter ablation targeting Purkinje potentials have been suggested.^3,4 However, most of the previous studies included only small numbers of patients in the acute phase of AMI.^4,9–11 Besides, the risk of procedure-related complications such as free wall perforation and cerebral infarction remains unknown. Therefore, the efficacy and safety of catheter ablation for refractory VT/VF occurring in the acute phase of AMI needs to be elucidated.

Thus, despite the advancements in management of AMI patients, VT/VF is still a serious complication of AMI, even in contemporary clinical practice, and especially in patients complicated with cardiogenic shock and/or refractory VT/VF. However, as our study included AMI patients treated with primary PCI between April 2000 and March 2019, there was limited involvement of the most recent advanced therapies for patients in the acute phase of AMI and so further clinical study focused on patients treated in the current era is highly warranted.

• Kenji Hanada, MD, PhD
• Hirofumi Tomita, MD, PhD, FJCS
• Department of Cardiology and Nephrology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan

References

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