Something currently being done in a clinical trial is placement of a transvenous lead into a coronary sinus branch vein in order to pace the left ventricle. "A completely transvenous lead system of course simplifies the procedure."
She also noted that current studies – such as MADIT II (Multicenter Automatic Defibrillator Implantation Trial II) and SCD HFT (Sudden Cardiac Death in Heart Failure Trial) – are examining whether CHF patients should prophylactically receive defibrillators. "Because these patients remain at risk for sudden cardiac death [SCD], this therapy is being looked at in CHF patients who have not even had sustained ventricular tachycardia [VT] or ventricular fibrillation [VF].
"Consequently, another development I foresee is a combined biventricular pacemaker and defibrillator. This makes sense in theory because many heart failure patients who have survived VT or VF receive defibrillator therapy, and eventually they succumb to pump failure. It’s a complex issue, because sudden deaths often occur in the setting of worsening heart failure. Implanting today’s defibrillators can reduce SCD mortality, but it can’t lower the mortality risk from progressive CHF. A defibrillator that offers biventricular pacing, however, might potentially treat both problems by reducing SCD and stabilizing pump function. To test this hypothesis, the VENTAK¨ CHF study is now under way."
Because of the sheer number of patients with a history of CHF and arrhythmias, Dr. Saxon said she believes this area could develop its own medical specialty. "This is a burgeoning area of interest now. And with the expanding knowledge base we expect in the next several years, I wouldn’t be surprised if a new cardiac specialty was eventually established with its own academic track."
According to Dr. Saxon, it will be some time before researchers know whether new pacing modalities, such as biventricular pacing, can affect mortality. "In both the VIGOR CHF and the VENTAK CHF studies, researchers are measuring the effects on only cardiac performance and quality of life. If we find positive results, it would of course be ideal if investigators went on to show prolonged survival, too.
"The use of pacing to treat CHF is a new frontier for us as investigators. There is room for much good work to be done in this area, and we are excited at the prospect of helping these patients whose choices are currently so limited." (guidant.com)