Guest Editorial

Dr. S. Manoj*

Senior Consultant and Interventional Cardiologist, Kauvery Hospital, Chennai, Tamilnadu, India

“A PERFECT DOUBLE WHAMMY killer – STEMI and VT Storm THREAT managed successfully”

ST Elevation myocardial infarction continues to be the leading cause of sudden cardiac death in India. Primary Ventricular Fibrillation still accounts for 10% immediate out-of-hospital mortality in STEMI globally. Early diagnosis by on-site ECG and time-bound coronary revascularization predominantly through Primary Angioplasty or Fibrinolysis has become standard of care in STEMI management in developing countries like India. Successful restoration of TIMI grade 3 flow in the iinfarct-relatedcoronary artery has significantly reduced the acute in hospital and 30-day mortality both from acute heart failure and ventricular arrhythmia.

Early post-MI is a vulnerable period for VT events from either ongoing myocardial ischemia – in cases of incomplete revascularisation, the development of proarrhythmic myocardial scar tissue, elevated sympathetic tone or increase in circulating catecholamines, or an electrolyte disturbance such as hypokalemia. In-hospital mortality upto 20% or more in patients who develop VT or VF following an MI is well known. Also, approximately 10% of post-MI survivors remain at high risk of dying in the first months or years following hospital discharge (mortality >25% at 2 years) [5]. Sudden death due to sustained VT or VF accounts for 50% of all deaths in these high-risk patients [6].

Ventricular tachy-arrhythmias can be life threatening in any subject more so in STEMI patients. VT storm or Electrical storm is present when a cluster of ventricular tachy-arrhythmias occurs within a short time frame and the most widely accepted definition is that of 3 or more such episodes of VT within a 24-h period. In patients with an implantable cardioverter-defibrillator (ICD), VT storm is defined as three or more appropriate therapies for ventricular tachyarrhythmias, including anti-tachycardia pacing (ATP) or shocks, within 24 h. This could be either a monomorphic VT, Polymorphic VT or VF events. However, the mortality risk escalates even if 2 or more VT events occur within 3 months period [1]. VT storm implies medical emergency requiring electrical cardioversions, heart failure / low cardiac output treatments in critical care set up. Such an electrical storm occurs typically in a structurally abnormal heart and the incidence of VT storm appears similar in patients with ischemic versus non ischemic cardiomyopathy [2]. It can also occur in patients with inherited channelopathies namely long QT, Brugada syndrome, catecholaminergic polymorphic VT [4]. Once myocardial ischemia as driving cause of VT Storm is excluded, a multimodality approach including pharmacologic therapy, anti-tachycardia pacing, catheter ablation and neuro-axial modulations of the autonomic nervous system followed by AICD implant is recommended vide (Fig. 1).

Fig. 1. Explains options of therapeutic approaches in VT storm management.

A meta-analysis of the available evidence reported a 2.5-fold increase in mortality in patients with Electrical Storm (ES) compared with patients with unclustered sustained Ventricular arrhythmia (VA), and a 3.3-fold increase in mortality compared with patients with no sustained VA [3]. An unfavourable sympathetic/parasympathetic activity may create the electrophysiological substrate required to initiate and maintain VT.

Figure 2

Fig. 2. explains the flow of algorithmic approach for VT storm choosing right therapeutic modality in a given clinical case of VT storm.

The case detailed by DCR et al clearly shows an underlying substrate trigger in RVOT location unrelated to the STEMI that initiates PVCs leading to Polymorphic degeneration into Torsades de Pointes with associated long Q-T condition co-existing. The case also elegantly illustrates how well a multi-modality and multi-disciplinary approach with a team of Interventional Cardiologist addressing the Primary PCI in STEMI situation followed by Cardiac electrophysiologist tackling the VT storm and Cardiac critical care specialist attention, successfully overcoming the DOUBLE WHAMMY killer events in a middle aged lady who could be discharged to home after a successful termination of the VT storm through substrate modification and final AICD implant for secondary prevention of SCD. It is therefore imperative to identify these high-risk patient subsets and make a timely referral to facilities providing such skilled care.

References

Parkash ER, et al. Mortality risk increases with clustered ventricular arrhythmias in patients with implantable cardioverter-defibrillators JACC: Clin Electrophysiol. 2020;6(3):327-37.
Streitner F, et al. Comparison of ventricular tachyarrhythmia characteristics in patients with idiopathic dilated or ischemic cardiomyopathy and defibrillators implanted for primary prevention Clin Cardiol. 2011;34(10):604-9.
Guerra F, et al. Capucci role of electrical storm as a mortality and morbidity risk factor and its clinical predictors: a meta-analysis. Europace. 2013;16(3):347-353.
Kumar S, et al. Beyond the storm: comparison of clinical factors, arrhythmogenic substrate, and catheter ablation outcomes in structural heart disease patients with versus those without a history of ventricular tachycardia storm. J Cardiovasc Electrophysiol. 2017;28(1):56-67.
Raviele A, et al. Prophylactic implantation of implantable cardioverter/defibrillator in post-myocardial infarction patients. In: Vardas PE, editor. Cardiac arrhythmias, pacing and electrophysiology. Dordrecht: Kluger Academic Publishers; 1998. pp. 305-310.
Uretsky BF, Sheahan RG. Primary prevention of sudden cardiac death in heart failure: will the solution be shocking? J Am Coll Cardiol. 1997;30:1589-159.

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