BOSTON —Shock therapy in patients with an implantable-cardioverter defibrillators (ICDs) can be decreased by aggressive programming changes, according to findings of the PROVIDE trial presented May 11 at the 33rd annual scientific sessions of the Heart Rhythm Society.
Mohammad Saeed, MD, and colleagues at the Texas Heart Institute at St. Luke’s Episcopal Hospital in Houston, studied the effectiveness and safety of such a strategy in a randomized, prospective fashion in a primary prevention (PP) patient population.
PROVIDE (Programming Implantable Cardioverter Defibrillators in Patients With Primary Prevention Indication) was a prospective, randomized study that involved patients receiving ICD for PP indications. Patients were randomized within 30 days of implant to either the experimental (higher detection rates, longer detection intervals, aggressive supraventricular tachycardia discriminators and extensive antitachycardia pacing [ATP] therapy) or the control group, which had standard programming parameters.
Patients were followed every three months for a minimum of 12 and up to 33 months during which device data were collected. The time to first shock and incidence of arrhythmia-related syncope were compared between the two groups.
A total of 1,674 patients were enrolled at 100 centers and followed for 18.3 months. There were no significant differences in the demographic characteristics between the two groups. The time to first shock in the experimental group was significantly longer than the control group (9.3 vs. 8.1 months) with a relative shock reduction of 33.6 percent in the experimental group (82 vs. 120 patients with shocks in the control group). The arrhythmic syncopal event rate was not significantly different between the two groups (1.7 percent in the experimental vs. 1.2 percent in the control groups).
Although shock therapy is effective in terminating ventricular tachycardia (VT), it can be painful to the patient and repetitive shocks can decrease a patient’s quality of life. Previous studies have suggested that one or more sets of aggressive device parameter settings may reduce the total number of shocks in PP patients. In addition to shock therapies, ATP also is available in ICDs to treat VT.
The researchers concluded that aggressive device parameter programming can prolong the time to first shock without increasing the risk of arrhythmic syncope in a PP patient population.
“ICDs are a great technology,” Saeed told Cardiovascular Business . “It prolongs the life of patients with heart disease by treating life-threatening arythmias.” One downside, he said, is that because it is computerized, depending on how it is programmed, sometimes it delivers shocks for wrong or inappropriate reasons. He emphasized that most of the time it treats patients with shock therapy for the right reasons, though.
Adding to the problem is that “over the last few years, indications have gotten more and more broad for the use of these devices,” Saeed said. “We’re getting into a problem where the patients who get these devices are getting more inappropriate shocks.” Those shocks result in more hospital visits, increased costs and patient burden.
ICDs come out of the box programmed very conservatively—skewed toward not missing any significant arrhythmias at the expense of delivering more inappropriate shocks, Saeed said. Changing the device settings resulted in a much lower incidence of inappropriate shocks, he said.
The decrease by almost 50 percent is “very, very significant,” he said. “I think that bodes very well for the patient getting the device put in because the device will only treat when it’s really necessary for life-threatening arrhythmia.”
Refining the settings for ICDs is a science which is in an evolution, Saeed said. Researchers are learning more and more about discriminators—the settings that distinguish between life-threatening and non-life-threatening arrhythmias.
“We’re now realizing that shocks are very psychologically and physically damaging for the patient,” he said. More physician education is needed because many “are afraid that if they program these newer settings, they might miss a life-threatening arrhythmia.” The data show that these fears are unfounded and that patients do very well and actually benefit, he said.
There is more work to be done to reduce unnecessary shocks, Saeed said, as 5 to 6 percent of PP patients in the trial still received inappropriate shocks.