"Perfect Electrical Assassin" Responsible For Many Unexplained Sudden Deaths

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a disorder triggered by exercise or stress in which the heart’s pumping chambers go into wild, uncontrolled rhythms that do not pump blood effectively. In contrast to long QT syndrome, another inherited heart rhythm condition, CPVT cannot be diagnosed through a resting electrocardiogram (ECG). The first indication of CPVT often is exercise-induced fainting or sudden death.

In up to 20 percent of sudden deaths involving young people, the cause of death remains a mystery even after a conventional autopsy. Michael Ackerman, M.D., Ph.D., director of the Long QT Syndrome Clinic and Sudden Death Genomics Laboratory at Mayo Clinic, says fatal electrical conditions may be the culprit in many sudden, unexplained death (SUD) cases.

"CPVT could be called the perfect electrical assassin, because it is difficult to detect in advance, and after death can only be identified by a molecular autopsy or by provocative stress testing in family members left behind," says Dr. Ackerman. "Our study shows for the first time how common it may be."

Dr. Ackerman led a molecular (genomic) autopsy study involving 49 young people (average age 14 years) who had died suddenly, and for whom the coroner or medical examiner had been unable to establish a cause and manner of death. The molecular autopsy found mutations that cause CPVT in seven cases, nearly 15 percent. Because the condition can be inherited, he says the findings should lead to testing of blood relatives in cases of unexplained death, either using stress tests or genetic evaluation.

"Treatments, including beta-blockers or implantable defibrillators, are available to prevent the catastrophic manifestations of CPVT," Dr. Ackerman says. "But we can’t treat what we haven’t diagnosed, so family members should be screened. Hopefully this work is a step toward preventing more of these tragedies."

Others who worked with Dr. Ackerman on this study are: David Tester and Daniel Spoon from Mayo Clinic; and Hector Valvidia, M.D., Ph.D., and Jonathan Makielski, M.D., from the University of Wisconsin.

A peer-review journal, Mayo Clinic Proceedings publishes original articles and reviews dealing with clinical and laboratory medicine, clinical research, basic science research and clinical epidemiology. Mayo Clinic Proceedings is published monthly by the Mayo Foundation for Medical Education and Research as part of its commitment to the medical education of physicians. The journal has been published for more than 75 years and has a circulation of 130,000 nationally and internationally. Copies of the article are available online at http://www.mayo.edu/proceedings.

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