A renaissance of an old cardiac therapy, left cardiac sympathetic denervation (LCSD), has provided another option and renewed hope for patients with malignant cardiac channelopathies, particularly long QT syndrome (LQTS) and catecholaminergic polymorphic ventricular tachycardia (CPVT).
Together, these 2 potentially lethal, highly treatable genetic heart rhythm disorders affect approximately 1 in 2,000 persons. The majority can be effectively managed with pharmacotherapy — mainly β-blockers — and simple preventive measures such as avoiding exposure to medications with an unwanted QT-prolonging adverse effect.
For some patients, however, these diseases are potently expressive. If the patient survives sudden cardiac arrest (SCA) or experiences a breakthrough cardiac event while on pharmacotherapy, an implantable cardioverter-defibrillator (ICD) represents a lifesaving and life-prolonging intervention.
Unfortunately, ICD placement has become an inappropriately rapid reflex in the management of LQTS. Fortuitously, the latest treatment advance with videoscopic denervation therapy has juxtaposed itself between pharmacotherapy and device therapy, where it may be more protective than pharmacotherapy, with fewer complications than device therapy.
LCSD is not new but was first surgically performed in a patient with incapacitating angina and arrhythmias more than 90 years ago. LCSD involves the surgical resection of the thoracic sympathetic ganglia at T2, T3, and T4, and the resection of the lower half of the left stellate ganglion (T1). This unilateral sympathectomy is antifibrillatory.
Unlike an ICD, which stands by to terminate a malignant arrhythmia, LCSD represents preventive therapy. Denervation makes it much more difficult for the LQTS/CPVT substrate to degenerate into ventricular fibrillation (VF) in the first place.
LCSD was first performed nearly 40 years ago for the management of a patient with high-risk LQTS. Analysis of its antifibrillatory effect in nearly 150 LQTS patients 5 years ago confirmed its very high success rate. Following this report, Michael J. Ackerman, M.D., Ph.D., a pediatric cardiologist and director of the Long QT Syndrome Clinic at Mayo Clinic, teamed with pediatric surgeon Christopher Moir, M.D., to develop videoscopic denervation therapy for the management of high-risk patients.
This procedural upgrade has occurred easily at Mayo Clinic because of its unique combination of one of the largest LQTS specialty centers in the world, extensive surgical experience with video-assisted thoracoscopic surgery (VATS), and integrated teamwork among Dr. Ackerman, Dr. Moir, and a team of anesthesiologists.
According to Dr. Moir, VATS-LCSD represents that natural next step in the maturation of denervation therapy. "In June 2009, we reported the perioperative and short-term outcomes associated with our first 20 VATS-LCSD procedures and, to date, we have performed more videoscopic denervations (more than 35) for the management of patients with LQTS/CPVT than any other center in North America," he says.
Like the experience regarding traditional surgical approaches to LCSD, the videoscopic approach has taken patients at extreme risk of future episodes of SCA and lowered their risk quite dramatically. A case in point is one of Mayo's first LCSDs, which was performed in a young woman with highly symptomatic, type 2 LQTS. She experienced approximately 15 VF-terminating ICD shocks during the year before LCSD. Now, nearly 4 years later, she has received only a single ICD shock, and in her own words, she has "gotten her life back."
Significant reduction in risk has been realized. To date, none of the VATS-LCSD has required conversion to an open surgical approach. Perhaps secondary to the outstanding anatomic exposure of the sympathetic chain in general and the left stellate ganglion specifically that is provided by the videoscopic approach, complications such as ptosis of the eyelid or Horner syndrome have not been observed.
Approximately half the patients referred for videoscopic denervation therapy have represented extreme phenotypes of LQTS/CPVT. Here, VATS-LCSD has been performed as secondary prevention, because of either recurrent VF-terminating ICD therapies or recurrent cardiac events despite adequate pharmacotherapy.
The other half have involved cases of so-called primary prevention in which videoscopic denervation therapy was provided to patients with β-blocker intolerance or for patients assessed to need more protection than just pharmacotherapy.
"LCSD's antifibrillatory effect also appears to be relatively substrate-independent, as patients with each of the 3 major LQTS genotypes and patients with CPVT have undergone denervation with both perioperative and short-term success," says Dr. Ackerman.
However, LCSD must not be viewed as curative. Recurrent events have been observed following denervation. Instead, videoscopic denervation therapy should be viewed as a minimally invasive approach to LCSD from which most patients are dismissed within 48 hours after surgery, complications are negligible, and risk of SCA is reduced significantly but not eliminated completely. In this context, a patient with LQTS/CPVT must undergo careful risk assessment to determine the right therapy for the right patient to be provided at the right time. More than 1,000 patients have been evaluated in the past decade in the LQTS Clinic at Mayo Clinic in Rochester.
In addition to LCSD's clearly established therapeutic role in LQTS/CPVT, Dr. Ackerman and Samuel J. Asirvatham, M.D., an electrophysiologist at Mayo Clinic, have joined a multicenter study to evaluate the role of LCSD for more common heart diseases associated with fatal ventricular arrhythmias. The study, PREVENT-VT, will randomly assign high-risk patients with ischemic heart disease to standard clinical therapy (ICD) or to ICD plus LCSD.
PREVENT-VT will likely begin patient enrollment in summer 2010. If LCSD's antifibrillatory effect is demonstrated among patients with ischemic heart disease in a similar manner to its protective role in LQTS/CPVT, then the number of patients who might benefit from this therapy will increase markedly.
It is possible that any patient with a history of VF-terminating ICD therapies may benefit from videoscopic denervation therapy, regardless of the particular cardiac pathology that has predisposed the heart to potentially lethal ventricular arrhythmias.