Ablation may be a better first-line treatment for heart attack survivors experiencing dangerous episodes of ventricular tachycardia (VT), according to late-breaking science presented recently at the American Heart Association (AHA) Scientific Sessions (16–18 November, Chicago, USA). This study has simultaneously been published in the New England Journal of Medicine.
Heart attacks create scar tissue in the heart muscle, which impedes the heart’s ability to function properly and may lead to other conditions like dangerous heart rhythms, as detailed in an AHA press release.
“The scarred heart tissue doesn’t contract and help with blood flow; however, sometimes, the scar contains surviving bits of heart muscle that create abnormal electrical circuits in the heart, leading to dangerous rapid heart racing called VT,” said lead author John Sapp (Dalhousie University/Queen Elizabeth II Health Sciences Centre, Halifax, Canada).
To reduce the risk of death from VT, patients may receive an implantable cardioverter defibrillator (ICD), which will shock the heart back into a normal rhythm. The ICD can be lifesaving, but it does not prevent VT.
“Even with an ICD, some patients still have recurrent attacks of VT—which causes serious symptoms, such as passing out—and the ICD shock itself can cause a very unpleasant feeling of being jolted or kicked in the chest,” Sapp noted.
The usual first treatment to prevent dangerous episodes of VT involves anti-arrhythmia medications. However, these medications may have serious long-term side-effects, such as worsening of the abnormal heart rhythm or potentially damaging other organs. When medication has been unsuccessful in reducing VT episodes, the second line of treatment is often catheter ablation—a minimally invasive procedure that uses radiofrequency energy to destroy the abnormal heart tissue causing the VT without damaging the rest of the heart.
“We have previously shown that, when a medication is not preventing episodes of VT, ablation has led to better outcomes than increasing the medications,” Sapp explained. “Now, we know that ablation is a reasonable option for first-line treatment instead of starting with antiarrhythmic medication therapy.”
In the VANISH2 trial, 416 patients (average age at enrolment, 68 years; 94% men) who developed recurrent VT after surviving a heart attack were enrolled at 18 health centres in Canada, two in the USA, and two in France. All participants had ICDs, and none had conditions that excluded them from receiving ablation or the antiarrhythmic medications used in the study. Treatment with medication or ablation was randomly determined. Patients assigned to medication received one of two antiarrhythmic medications: amiodarone or sotalol.
Participants were followed for at least two years after ablation or while taking the assigned medications (median, 4.3 years). Researchers tracked death, appropriate ICD shocks, three or more VT events within 24 hours, and sustained VT that was treated urgently in a hospital rather than by the patient’s ICD.
Their analyses ultimately found that people who received ablation were 25% less likely to die or experience VT requiring an ICD shock. This included having three or more VT episodes in a single day, or VT episodes that were not detected by the ICD and were treated in a hospital.
“Although the study was not large enough to show a statistically definitive effect on all of the parameters that are important to patients and physicians, patients treated with ablation also had fewer ICD shocks for VT, fewer ICD treatments, [fewer] episodes of three or more VT in a single day, and fewer VT episodes not detected by their ICD,” Sapp reported. “For people who have survived a heart attack and developed VT, our findings show that performing a catheter ablation to directly treat the heart’s abnormal scar tissue causing the arrhythmia,—rather than prescribing heart rhythm medications that can affect other organs as well as the heart—provides better overall outcomes. These results may change how heart attack survivors with VT are treated.
“Currently, catheter ablation is often reserved as a last-resort therapy when antiarrhythmic medications fail or cannot be tolerated. Now, we know that ablation is a reasonable option for first-line treatment. We hope that our data will be useful for clinicians and patients who are trying to decide the best option when they need treatment to suppress recurrent VT and prevent ICD shocks.”
Although the study could not confirm if ablation worked better than medication to reduce each outcome tracked, the researchers found that, overall, the differences favoured ablation. The study also did not determine which patients with particular characteristics would benefit more from one treatment or the other.
“In addition, these results cannot be generalised to patients who have heart muscle scarring caused by a disease other than a blocked coronary artery,” Sapp said. “We also note that, despite these treatments, the rate of VT episodes remained relatively high. We still need more research and innovation to develop better treatments for these patients.”
