Sarasota Memorial Health Care System is one of up to 40 research sites enrolling patients in the international HEAL-IST trial, a clinical study evaluating a hybrid ablation procedure for people with inexplicably high resting heart rates. IST, short for inappropriate sinus tachycardia, is a challenging condition in otherwise healthy people that causes the heart to race over 100 beats per minute at rest, and dangerously higher with activity. IST is thought to be caused by dysfunction of the sinus node – the heart’s natural pacemaker – or issues with the body's nervous system. Currently, there are no FDA-approved therapies to treat IST. Medications like beta blockers, calcium channel blockers, and ivabradine are usual first treatments, but often are ineffective. Sinus node modification and radiofrequency sinus node ablation also have been used, but the interventional techniques often involve a higher risk of complications. The HEAL-IST trial is evaluating a hybrid sinus node sparing procedure that combines surgical and catheter-based techniques performed by a cardiac surgeon and electrophysiologist. Using study sponsor AtriCure’s Isolator Synergy clamp and mapping technology, the hybrid approach allows the team to ablate and create scar lesions on the inside and outside of the heart, with the goal of sparing the sinus node and lowering the rapid heart rate responsible for IST. First Physicians Group cardiothoracic surgeon Paul Vesco, MD, who is principal investigator for the SMH study, said previous trials comparing hybrid ablation with sinus node modification found that hybrid ablation lowered the average heart rate more effectively over 12 months than the traditional method. He said the HEAL-IST study will provide more information on the safety and effectiveness of this novel approach. IST affects about 1 percent of the population. Symptoms can be disabling and include palpitations, dizziness, fatigue, light-headedness or fainting, difficulty exercising, chest discomfort and shortness of breath. The condition, which occurs more commonly in younger women, is often overlooked, and sometimes misdiagnosed as panic attacks or emotional disorders.