Dr. John Sapp’s discovery brings hope for ventricular tachycardia patients.
Thousands of Canadians are saved each year by internal defibrillators inserted in their bodies that zap their hearts back on track when they’re threatened by dangerous rhythms.
But the side effects include pain and trauma. Now, a 鶹ý alum, researcher and cardiologist with Nova Scotia Health, Dr. John Sapp (MD’94), has determined the most effective way to limit the shocks, prompting a re-evaluation of heart treatment worldwide.
“Ventricular tachycardia (VT) is the most common cause of sudden death. I would venture to say you and anyone you talk to knows, within one degree of separation, somebody who died suddenly from the condition,” says . “It’s great that internal defibrillators can shock us back, but getting a lot of shocks can be pretty traumatic.”
Aside from the ongoing apprehension that a jolt could come at any second, Dr. Sapp says the shocks can be an important indicator that things are not going well with the heart overall. “So, there's a real impetus for us to prevent recurrent arrhythmias and the shocks that come with them."
Seeking a solution, Dr. Sapp has worked for years with colleagues at Nova Scotia Health and around the world to study the relative success of the two leading treatments — drugs and the minimally invasive procedure known as catheter ablation. Using wires that are snaked to the heart through blood vessels in the thigh, catheter ablation allows doctors to discover and cauterize short circuits that cause the heart to misfire.
Catheter ablation outperforms medication
“Historically, the practice has been to try medications first, and if medications weren't working, try still more medications,” says Dr. Sapp, noting that this remained the case even after his 2016 study that demonstrated catheter ablation provides a safer option than stronger drugs.
But now a global rethink is underway, sparked by Dr. Sapp’s most recent study of the treatments. Published in the in February 2025, Dr. Sapp’s findings demonstrate for the first time that catheter ablation outperforms medication as the first-line VT treatment.
Dr. Sapp’s study tracked 416 VT patients implanted with defibrillators after surviving a heart attack. Enrolled in 22 health centers, including Nova Scotia Health’s QEII Health Sciences Centre, patients were randomly assigned to either drug therapy — amiodarone or sotalol — or catheter ablation. The question: which approach reduced VT incidents and posed less risk?
Potential to impact treatment worldwide
For at least two years, researchers tracked participants’ erratic heartbeats, electric jolts, and emergency visits. A pattern emerged — patients who underwent ablation had a 25 per cent lower rate of death, VT-related shocks, emergency treatment of VT, or clusters of dangerous arrhythmias called VT storms.
While often effective, Dr. Sapp says VT drugs come with the risk of side effects. The leading drug can damage organs over time; the next in line can paradoxically increase the odds of life-threatening arrhythmias. The better effectiveness of ablation and risks of side effects are what Dr. Sapp says set medication behind ablation as the preferred treatment for most patients.
“This could be a landmark trial that could have an important impact in how people are cared for around the world,” says Dr. Sapp.
Satisfied patient
None of this suprises patient John Kell, who has VT. Previous damage to his heart makes it prone to race spontaneously, misfiring and contracting so fast that the ventricles barely had time to fill with blood, starving his body of oxygen. Kell has an implanted defibrillator that regularly gives him jolts. He was part of Dr. Sapp’s most recent study in 2019, and says he hasn’t experienced any shocks since having catheter ablation.
“It’s good mentally to know it’s not going to happen,” says Kell, who is retired from farming but still appreciates the ability to walk and oversee his land. “I don’t notice any difference now. It’s there and it’s working. That’s all I want.”
