Ablation may provide better results than drug treatment for ventricular tachycardia

Ablation, a procedure to treat abnormal electrical circuits caused by a heart attack and typically used in patients who do not improve with medication, may be a more effective primary treatment for heart attack survivors who experience dangerous episodes of rapid heartbeat, according to new data presented today at the 2024 American Heart Association Scientific Sessions. The meeting, taking place November 16-18, 2024, in Chicago, is the world’s leading forum for sharing the latest scientific advances, research, and clinical practice updates in cardiovascular science. The study is also published in The New England Journal of Medicine.

Heart attacks create scar tissue in the heart muscle, which interferes with the normal functioning of the heart and can lead to conditions such as dangerous heart rhythms.

"Scar tissue in the heart does not contract and does not help blood flow, but sometimes the scar contains surviving sections of heart muscle that create abnormal electrical circuits, causing dangerous ventricular tachycardia," explained Dr. John Sapp, lead author, professor of medicine and associate dean for clinical research at Dalhousie University's Queen Elizabeth II Health Care Centre in Halifax, Nova Scotia, Canada.

Ventricular tachycardia (VT) is the most common cause of sudden cardiac death. It is a rapid heartbeat that begins in the lower chambers of the heart (ventricles) and prevents the heart chambers from filling completely with blood between beats, reducing blood flow to the rest of the body.

To reduce the risk of death from VT, a patient may be given an implantable cardioverter defibrillator (ICD), which uses an electrical shock to restore the heart's normal rhythm. An ICD can be life-saving, but it does not prevent VT. "Even with an ICD, some patients have recurrent episodes of ventricular tachycardia, which can cause serious symptoms such as loss of consciousness, and the shock from the ICD itself can be extremely uncomfortable, like being hit in the chest," Sapp added.

Antiarrhythmic drugs are usually the first treatment to prevent dangerous episodes of VT. However, these drugs can have serious long-term side effects, including worsening the abnormal heart rhythm or damaging other organs. When medications fail to reduce the frequency of VT episodes, ablation is the second treatment. This minimally invasive procedure uses radiofrequency energy to destroy the abnormal heart tissue causing VT without damaging the rest of the heart.

"We have already shown that when medications fail to prevent VT episodes, ablation results in better outcomes than intensifying drug therapy. We now know that ablation may be a reasonable option for initial treatment instead of initiating antiarrhythmic drug therapy," Sapp said.

The Ventricular Tachycardia: Antiarrhythmics or Ablation in Structural Heart Disease 2 (VANISH2) trial enrolled 416 patients who developed recurrent VT after surviving a heart attack. Patients were recruited at 22 centers in three countries. All participants had an ICD inserted to restore heart rhythm if needed. Participants who were not contraindicated for ablation or antiarrhythmic drugs were randomly assigned to receive either ablation or one of two antiarrhythmic drugs: amiodarone or sotalol.

Participants were followed for at least two years after ablation or while taking prescribed medications (median follow-up, 4.3 years). The researchers tracked deaths, adequate ICD shocks, three or more episodes of VT within 24 hours, and sustained VT not recognized by the ICD but requiring emergency hospital treatment.

Data analysis showed:

People who had ablation were 25% less likely to die or experience VT requiring an ICD shock. This included three or more episodes of VT in a day or episodes of VT not detected by the ICD and treated in the hospital. “While the study was not large enough to show statistically significant effects on all the measures that matter to patients and physicians, patients who had ablation also had fewer ICD shocks for VT, fewer ICD treatments, fewer episodes of three or more VTs in a day, and fewer VTs not detected by their ICD,” Sapp said.

"For heart attack survivors with VT, our results show that catheter ablation, which targets the scar tissue in the heart that is causing the arrhythmia, provides better overall outcomes than giving drugs that may affect not only the heart but other organs as well," he continued. "These findings may change the way we treat heart attack survivors with VT.

"Currently, catheter ablation is often used as a last resort when antiarrhythmic drugs fail or are not tolerated. We now know that ablation may be a reasonable option for primary treatment. We hope that our data will be useful to clinicians and patients trying to decide the best treatment option to suppress recurrent VT and prevent ICD shocks," Sapp said.

While the study couldn’t confirm that ablation worked better than drugs at reducing each outcome tracked, the researchers found that the overall differences favored ablation. The study also didn’t determine which patients with certain characteristics would benefit more from one treatment over another.

"In addition, these results cannot be generalized to patients whose heart muscle scarring is caused by disease other than a blocked coronary artery," Sapp said. "It is also worth noting that despite these treatments, the rate of VT episodes remains relatively high. We still need more research and innovation to develop better treatments for these patients."

Research details, background and design:

Participants included 416 adults (mean age 68 years) who had had a heart attack (mean age 14 years earlier) and had an ICD. None had contraindications to the study drugs or the ablation procedure. Patients were from 18 centers in Canada, two in the United States, and two in France. Patients were randomly assigned to receive either catheter ablation or one of two antiarrhythmic drugs (sotalol 120 mg twice daily or amiodarone 200 mg daily after a standard starting dose) to suppress recurrent episodes of dangerous palpitations and reduce the number of ICD shocks. Follow-up was at least 2 years (median 4.3 years). The investigators tracked the composite outcomes of death, VT with an ICD shock, three or more VT episodes per day, and VT below the device detection level requiring emergency treatment. Selected primary outcomes, other medical outcomes, arrhythmias, and potential adverse reactions to treatment were also considered.