more evidence that gene therapy is the future.
Genetics Seen as Key to Future Arrhythmia Management
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WASHINGTON, May 25 (Reuters Health) - Improvements in the management of cardiac arrhythmias will stem from advances in genetic knowledge and technological sophistication, according to a series of presentations made here at the 21st annual Scientific Sessions of the North American Society of Pacing and Electrophysiology.
"It's mostly about genes," Dr. Augustus Grant, of Duke University, in Durham, North Carolina, said in his discussion of basic arrhythmia research. He sees genetics as aiding in the diagnosis not only of Mendelian traits (eg, long QT syndrome), but also of complex, multifactorial diseases.
"By establishing a genetic profile, perhaps using multiple loci markers or single nucleotide polymorphisms, we can undertake appropriate preventive measures early and encourage lifestyle choices suited to an individual's genetic makeup," Dr. Grant said.
Dr. Dan Roden, of Vanderbilt University, in Nashville, Tennessee, sees genomics in the future of pharmacological therapies for arrhythmias, too. He described the new field of pharmacogenomics as "the study of the impact of diversity in the individual's or population's genome on their response to drug therapy."
Pharmacogenomics, said Dr. Roden, will influence antiarrhythmic therapy in at least three ways. First, it will allow pre-prescription genotyping, so that the best drug at the best dose can be used for any particular condition. Second, scientists will be able to develop safe drugs targeting genetically specific disease mechanisms. Third, it will be possible to add specific genotypes to the current risk factors for such conditions as sudden cardiac death.
Dr. Eric Prystowsky, of Northside Cardiology, in Chicago, Illinois, and Dr. David Hayes, of Mayo Clinic, in Rochester, Minnesota, discussed the future pacemaker treatment of tachycardia and bradycardia. Both envision technological advancements that will enable pacemakers to sense multiple cardiac physiological states and to deliver medications directly to the heart in response to the conditions detected.
Dr. Hayes summarized their predictions by saying simply, "Pacemakers need to be smaller and smarter."
"Noninvasive testing has been plagued with unacceptably low positive predictive values," lamented Dr. Michael Cain, of Washington University, in St. Louis, Missouri. "In the future, our tests need to consider the pathogenesis of arrhythmias, rather than merely epiphenomena."
Dr. Cain anticipates using noninvasive tests in combination to improve their predictive value. He predicted wider use of high-resolution signal-averaged electrocardiography (SAECG) in capturing signals responsible for early activations and derangements in repolarization. "More varied ECG lead placement may also enable us to capture the spatial distribution of signals, particularly from post-MI patients with ventricular tachycardia," he said.
Catheter ablation of arrhythmias will become much more widely used, according to Dr. Warren Jackman, of the University of Oklahoma, in Oklahoma City, and Dr. Fred Morady, of the University of Michigan, in Ann Arbor.
"Besides rapid, very high resolution mapping," Dr. Jackman predicted, "we will have catheter manipulation by robotic control to allow a fully automated characterization of the heart's chambers." He also expects ablation energy sources other than radiofrequency to be available soon. Among the possibilities, he said, are ultrasound energy, cryoablation and laser ablation.
Dr. Morady foresees the end of electrophysiology studies for most patients. "Within a few years," he said, "we'll be implanting miniature ICDs with or without ablation for sustained ventricular tachycardia, aborted sudden death, nonsustained ventricular tachycardia with low ejection fractions, even unexplained syncope with heart disease ? all on an outpatient basis, and without EP studies." |
