Long-Term Outcomes of Inducible Very Fast Ventricular Tachycardia (Cycle Length 200-250 ms) in Patients With Ischemic Cardiomyopathy

Influence of standard modifiable risk factors on ventricular tachycardia after myocardial infarction

Background

Inducible ventricular tachycardia (VT) at electrophysiology study (EPS) predicts sudden cardiac death because of ventricular tachyarrhythmia, the single greatest cause of death within 2 years after myocardial infarction (MI).

Objectives

We aimed to assess the association between standard modifiable risk factors (SMuRFs) and inducible VT at EPS early after MI.

Methods

Consecutive patients with left ventricle ejection fraction ≤40% on days 3-5 after ST elevation MI (STEMI) who underwent EPS were prospectively recruited. Positive EPS was defined as induced sustained monomorphic VT cycle length ≥200 ms for ≥10 s or shorter if hemodynamically compromised. The primary outcome was inducibility of VT at EPS, and the secondary outcome was all-cause mortality on follow-up.

Results

In 410 eligible patients undergoing EPS soon (median of 9 days) after STEMI, 126 had inducible VT. Ex-smokers experienced an increased risk of inducible VT [multivariable logistic regression adjusted odds ratio (OR) 2.0, p = 0.033] compared with current or never-smokers, with comparable risk. The presence of any SMuRFs apart from being a current smoker conferred an increased risk of inducible VT (adjusted OR 1.9, p = 0.043). Neither the number of SMuRFs nor the presence of any SMuRFs was associated with mortality at a median follow-up of 5.4 years.

Conclusions

In patients with recent STEMI and impaired left ventricular function, the presence of any SMuRFs, apart from being a current smoker, conferred an increased risk of inducible VT at EPS. These results highlight the need to modify SMuRFs in this high-risk subset of patients.

Electrophysiology testing for risk stratification of patients with ischaemic cardiomyopathy: a call for action

Current guidelines recommendations, based on the results of primary sudden cardiac death prevention trials, use the left ventricular ejection fraction (LVEF) as a sole criterion for the indication of implantable cardioverter defibrillator therapy for primary prevention purposes. In this article, we review the sensitivity and specificity of LVEF for predicting arrhythmic vs. non-arrhythmic cardiac death and examine existing evidence on the use of electrophysiology testing for risk stratification of ischaemic patients with reduced left ventricular function.

[Risk stratification for sudden cardiac death in ischemic heart disease. Programmed ventricular stimulation]

Programmed ventricular stimulation was used extensively in the 1970s and has markedly improved our knowledge about the electrophysiological mechanisms of reentrant ventricular arrhythmias. In numerous observational but also randomized studies, it was shown that the induction of a monomorphic ventricular tachycardia by programmed ventricular stimulation was associated with an increased risk of spontaneous ventricular tachycardia or even sudden cardiac death in the future. Despite these results and the guidelines of ACC and ESC recommending the use of programmed ventricular stimulation in patients with recent and remote myocardial infarction, reduced ejection fraction, and complex ventricular arrhythmias or syncope, programmed ventricular stimulation is only seldom used and does not play a relevant role in clinical practice today. The purpose of this overview is to reevaluate the importance of programmed ventricular stimulation for the risk evaluation of patients with ischemic heart disease in consideration of the current literature.

Ventricular tachyarrhythmia recurrence in primary versus secondary implantable cardioverter-defibrillator patients and role of electrophysiology study

PURPOSE

In recent years, there has been a shift away from performing electrophysiologic study (EPS) to guide implantable cardioverter-defibrillator (ICD) implantation with a reliance on left ventricular ejection fraction (LVEF) alone.

METHODS

ICD patients were prospectively recruited from the multicentre COMFORT (Concept of Optimal Management of ventricular Fibrillation Or Very fast ventricular Tachycardia) trial. Primary prevention ICD patients (n = 260, groups 1 and 2) were compared to secondary prevention ICD patients (n = 210, group 3). Primary prevention ICDs were implanted in patients with ischemic cardiomyopathy based on LVEF ≤ 40 % and inducible ventricular tachycardia (VT) at EPS (n = 123, group 1) or impaired LVEF alone (LVEF ≤ 30 % or LVEF ≤ 35 % with NYHA class II or III; n = 137, group 2). EPS was performed in 61 % of secondary prevention ICD patients (n = 129). Patients were followed up for >12 months with a primary endpoint of spontaneous VT/ventricular fibrillation (VF).

RESULTS

A significantly higher rate of spontaneous VT/VF occurred in secondary versus primary prevention ICD patients (P < 0.001) and in EPS-guided versus LVEF-guided primary prevention ICD patients (P = 0.029). At 2 years, the proportion of patients with ≥1 VT/VF episode was 24.6 ± 4.2 %, 19.9 ± 4.6 % and 37.1 ± 3.9 % for groups 1, 2 and 3, respectively. In the secondary prevention, patients who underwent EPS, VT/VF occurred in 44.4 ± 5.9 % and 14.1 ± 6.6 % with a positive versus negative result, respectively (P = 0.02).

CONCLUSIONS

Secondary prevention ICD patients have more spontaneous VT/VF than primary prevention ICD patients. Secondary and primary prevention ICD patients with inducible VT at EPS have more VT/VF than patients without inducible VT or impaired LVEF alone.

Long-term arrhythmia-free survival in patients with severe left ventricular dysfunction and no inducible ventricular tachycardia after myocardial infarction

BACKGROUND

A negative electrophysiology study (EPS) may delineate a subgroup of patients with severely impaired left ventricular ejection fraction (LVEF) whose care can be safely managed long-term without an implantable cardioverter-defibrillator.

METHODS AND RESULTS

Consecutive patients treated with primary percutaneous coronary intervention for ST-segment-elevation myocardial infarction underwent early (median 4 days) LVEF assessment. Patients with LVEF ≤40% underwent EPS. A prophylactic implantable cardioverter-defibrillator was implanted for a positive (inducible monomorphic ventricular tachycardia) but not a negative (no inducible ventricular tachycardia or inducible ventricular fibrillation/flutter) EPS result. Patients who would have become eligible for a late primary prevention implantable cardioverter-defibrillator with LVEF ≤30% or ≤35% with New York Heart Association class II/III heart failure were included and analyzed according to EPS result. Patients with LVEF >40%, ineligible for EPS, were followed up as control subjects (n=1286). The primary end point was survival free of death or arrhythmia (resuscitated cardiac arrest or sustained ventricular tachycardia/ventricular fibrillation). EPS performed in 128 patients with LVEF ≤30% or with LVEF ≤35% and heart failure was negative in 63% (n=80) and positive in 37% (n=48). Implantable-cardioverter defibrillators were implanted in <0.1%, 4%, and 90% of control, EPS-negative, and EPS-positive patients, respectively. The distribution of time to death or arrhythmia was comparable in control patients and EPS-negative patients with LVEF ≤30% or with LVEF ≤35% and heart failure (P=0.738), who both differed significantly from EPS-positive patients (P<0.001). At 3 years, 91.8 ± 3.2%, 93.4 ± 1.0%, and 62.7 ± 7.5% of control, EPS-negative, and EPS-positive patients were free of death or arrhythmia, respectively.

CONCLUSIONS

Revascularized patients with ST-segment-elevation myocardial infarction with severely impaired left ventricular function but no inducible ventricular tachycardia have a favorable long-term prognosis without the protection of an implantable cardioverter-defibrillator.

Primary Radiofrequency Ablation of Ventricular Tachycardia Early After Myocardial Infarction

Background—

Ventricular tachycardia (VT) is a significant complication of myocardial infarction. Radiofrequency ablation for postinfarct VT is reserved for drug refractory VT or VT storms. Our hypothesis is that radiofrequency ablation in the early postinfarct period could abolish or diminish late recurrences of VT.

Methods and Results—

Myocardial infarct was induced by balloon occlusion of the left anterior descending artery in 35 sheep. The 25 survivors underwent programmed ventricular stimulation and electroanatomical mapping 8 days postinfarct. Animals with inducible VT (12 out of 25 animals) underwent immediate radiofrequency ablation. Further VT inductions were performed 100 and 200 days postinfarct. At day 8, 3.0±0.9 VT morphologies per animal were inducible. All were successfully ablated with 24±6 applications of radiofrequency energy. All had ablations on the left ventricular endocardium, and 67% had ablations on the right ventricular aspect of the interventricular septum. All targeted arrhythmias were successfully ablated acutely. One animal was euthanized because of hypotension from a serious pericardial effusion. The other 11 survived and remained arrhythmia free on subsequent inductions on the 100th and 200th days ( P <0.001). The 13 animals without inducible VT remained noninducible at the subsequent studies. A historical control arm of 9 animals with inducible VT at day 8 remained inducible at day 100.

Conclusions—

Radiofrequency ablation on the eighth day after infarction abolished inducibility of VT at late induction studies ≤200 days in an ovine model. Early identification and ablation of VT after infarction may prevent or reduce late ventricular arrhythmias but needs to be validated in clinical studies.

Antitachycardia pacing for very fast ventricular tachycardia and low-energy shock for ventricular arrhythmias in patients with implantable defibrillators

Implantable cardioverter-defibrillator therapy in the form of high-energy shock (HES) is associated with adverse effects. This study evaluated an alternative therapy to HES, including antitachycardia pacing (ATP) for very fast ventricular tachycardia (VFVT) and low-energy shock (LES) ≤5 J for ventricular tachycardia (VT) of any cycle length (CL). This multicenter study recruited 602 patients with standard indications for an implantable cardioverter-defibrillator. Programming was standardized into 3 zones: (1) ventricular fibrillation (VF) CL of <200 ms treated with HES; (2) VFVT defined within the VF zone (CL, 200 to 250 ms) treated with 2 ATP bursts, LES, and HES; and (3) fast ventricular tachycardia (CL, 251 to 320 ms) and slow VT (CL, >320 ms) treated with 3 ATP bursts, LES, and HES. The primary end point was ATP and LES efficacy and safety. After a mean follow-up of 19 ± 8 months, 2,815 device activations were recorded in 152 patients. Of 67 VFVT episodes, 34 reverted with combined ATP and LES (success rate 50.7%) with first and second ATPs successful in 36% and 13.8%, respectively. LES was used in 39 fast ventricular tachycardia and 60 slow VT episodes with success rates of 53.8% and 73.3%, respectively. Syncope occurred in 19.4%, 16.2%, and 1% of episodes because of VFVT, VF, and VT CL >250 ms, respectively. In conclusion, tiered ATP and LES therapy terminates >50% of VFVT episodes (CL, 200 to 250 ms), which otherwise would fall within the VF zone and be treated exclusively with HES. LES is efficacious and safe in patients with VT CL >250 ms with extremely low syncope rates. Limitation of ATP to a single burst in VFVT is recommended to minimize syncope.