Patients with ischemic heart disease and VT. Drugs or ablation as a first-line treatment?

Heart attacks leave areas of scars mixed with healthy myocytes, generating areas of slow conduction within the scars, giving rise to a favorable environment for the origination of ventricular tachycardia (VT) by reentry mechanism. We all agree that in this type of scenario the implantable cardioverter-defibrillator (ICD) effectively prevents sudden death^1,2. However, ICD does not prevent TV generation. In turn, each adequate shock is not only a traumatic and painful situation for the patient, but also affects their quality of life, reduces device longevity, and is associated with reduced ventricular function and, possibly, increased mortality. Therefore, when faced with a patient with ICD and symptomatic VT, it is essential to offer something more.

SURVIVE-VT ¹ is a randomized trial, carried out in 9 centers in Spain. It compares catheter ablation (AC) versus antiarrhythmic drugs (AAD) as first-line treatment in patients with ischemic heart disease and symptomatic VT or ICD shocks. It included 145 patients (average age 70 years, 96% male, average FEY 34%) who were randomized to AC (n=71) or FAA (n=73). They all had chronic ischemic heart disease, a recent history of ICD shocks or symptomatic VT, and no antiarrhythmic pharmacological treatment. The primary endpoint was a composite of cardiovascular death, appropriate ICD shock, hospitalization for worsening heart failure, or serious treatment-related complications. Patients in the ablation group underwent substrate-guided ablation. Patients in the drug group could receive amiodarone alone, amiodarone plus beta-blockers, or sotalol. 86% received amiodarone.

After 24 months of follow-up, the primary endpoint was significantly reduced in the AC group by 28.2% vs 46.6% (Hazard Ratio [HR]: 0.52; P = 0.021). The number of patients to be treated to prevent a case with the primary endpoint was 4.6. The benefits in the AC group were mainly due to a significant reduction in treatment-related complications (9.9% vs 28.8% HR: 0.30; P = 0.006) and a non-significant trend towards fewer hospitalizations for heart failure (HR: 0.56; P = 0.198). There were no differences in mortality or ICD shocks.

The ad hoc analysis shows that in the AC group there was a significant reduction in the recurrence of slow VT not detected by the CD (1.4% vs 13.7% HR 0.18) and hospitalizations for VT. The crossover rate was higher in the FAA group (24.3% vs. 10.1%).

These results lead the authors to conclude that CA guided by substrate modification, performed in sinus rhythm and without the need for VT induction, reduces the primary point of safety and efficacy.

COMMENTS:

SURVIVE-VT tries to solve a very common clinical situation: a patient with ischemic heart disease with ICD who has VT. What do we do? Do we start pharmacological treatment and wait to see if there is a recurrence and then propose ablation? Or do we propose ablation as a first option? LAHRS Guidelines, carried out in conjunction with HRS/EHRA/APHRS, do not recommend ablation in these cases (indication IIb, level of evidence A), but in those who have recurrent VT despite treatment with amiodarone (indication I, level of evidence B-R )⁴.

The results obtained suggest that ablation, as a first line, would be better than pharmacological treatment, mainly due to the significant reduction in treatment-related complications (10% vs 29% HR 0.30 P=0.006). So, let’s focus on treatment and adverse effects.

In the FAA group, it was used mainly (86% with amiodarone), the most effective drug, but with the highest rate of adverse reactions. In the AC group, the substrate-guided ablation technique was used, which is based on the elimination of potential isolated sites to achieve scar homogenization, eliminating the transition zones between fibrosis and healthy myocytes. As there is no need to induce VT during the intervention, adverse reactions resulting from hemodynamic compromise due to repetitive VT induction are avoided. We could say that the ablation branch used the safest technique. We currently do not have solid data to support the use of one ablation technique over the other. In fact, the VISTA ⁵ study showed that substrate ablation, compared with clinical ablation, significantly reduced VT recurrence at 12 months and combined re-hospitalization and mortality.

Considering that the ablations were performed in centers with extensive experience in these procedures, 10% of complications is not a negligible number. And a separate debate requires a qualitative, not just quantitative, analysis of the complications between the two groups. In the ablation group, some of the complications were stroke and heart block. While in the pharmacological group, sinus bradycardia and hypothyroidism were quantified as serious complications.

It would have been expected that ablation would reduce the primary point by reducing VT recurrence. However, there was no reduction in ICD shocks, mortality or any type of VT (27% vs 29% P=0.42).

On a positive note, ablation significantly reduced slow TV episodes. And this is not a minor observation. Slow VT, as it is not detected and treated by the ICD, favors patient decompensation, increased hospitalizations and even requires external cardioversion. This could explain the trend towards a lower number of hospitalizations for heart failure observed in the AC group.

Finally, SURVIVE-VT highlights the high rate of adverse reactions to antiarrhythmics during follow-up and that catheter ablation “might” be considered first-line therapy in patients with ischemic heart disease and first-episode VT. We need more information to change “might” to “must”. The great advances in the field of ablation compared to the few advances in the field of antiarrhythmics make us very optimistic about the future.

Bibliografía

1. Arenal A, Ávila P, Jiménez-Candil J, et al. Substrate ablation vs antiarrhythmic drug therapy for symptomatic ventricular tachycardia. J Am Coll Cardiol. 2022;79:1441–1453.

2. Moss AJ, Zareba W, Hall WJ, et al. Prophylactic implantation of a defibrillator in patients with myocardial infarction and reduced ejection fraction. N Engl J Med. 2002;346:877–83.

3. Poole JE, Johnson GW, Hellkamp AS, et al. Prognostic importance of defibrillator shocks in patientswith heart failure. N Engl J Med. 2008;359:1009–1017.

4. Cronin E, Bogun FM, Maury P et al. 2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias. Europace 2019; 21:1143–1144

5. Di Biase L, Burkhardt JD, Lakkireddy D, et al. Ablation of stable VTs versus substrate ablation in ischemic cardiomyopathy. The VISTA randomized multicenter trial. J Am Coll Cardiol. 2015;66:2872–2882.