Tuesday, January 26, 2016

Overdiagnosed or overtreated prolonged QT syndrome

Prakriti Gaba,  J. Martijn Bos,  Bryan C. Cannon,  Yong-Mei Cha,  Paul A. Friedman,  Samuel J. Asirvatham, Michael J. Ackerman. Implantable cardioverter-defibrillator explantation for overdiagnosed or overtreated congenital long QT syndrome. Heart Rhythm. Published Online: December 08, 2015.



Primary treatment of long QT syndrome (LQTS) currently consists of beta-blocker therapy, although an implantable cardioverter-defibrillator (ICD) is considered for high-risk patients. However, both overdiagnosis and overtreatment must be avoided because their sequelae can be significant.


The purpose of this study was to evaluate the prevalence and details of ICD explants in a cohort of patients from a tertiary genetic heart rhythm clinic for a previously rendered diagnosis of LQTS.


Overall, 1227 consecutive patients were included in the study. All patients had been referred to the Mayo Clinic for evaluation of possible LQTS and subsequently were either diagnosed with LQTS or dismissed as normal. Further stratification of patients was conducted to assess how many patients had an ICD and how many had a subsequent ICD explant.


In total, 171 patients (14%) had an ICD, including 157 of 670 patients (23%) with confirmed LQTS and 13 of 557 patients (2%) who did not have LQTS. Among these, 12 of 1227 (1%) had the ICD removed: 7 of 157 LQTS patients (4.5%) compared to 5 of 14 non-LQTS patients (36%). Before explant, 5 of 12 patients (42%) experienced inappropriate shocks, ranging from 2 to as many as 54 shocks. In addition, 4 had a device-related infection, and 9 had device malfunction (including lead dysfunction or fracture). None of these patients had a breakthrough cardiac event since removal of their ICD during 5.5 ± 3.5 years of follow-up.


Implications of overdiagnosis and overtreatment are profound because unnecessary ICD placement can be associated with infection, malfunction, inappropriate shocks, and subsequent anxiety.

Courtesy of:  http://www.medscape.com/viewarticle/857075

1 comment:

  1. "In this present study, not only are patients continuing to be overdiagnosed, but among those patients correctly diagnosed with LQTS, there appears to be a premature rush to an ICD," write the authors, led by Dr Michael Ackerman (Mayo Clinic, Rochester, MN)...

    In an editorial published online December 24, 2015 in the same journal[2], Dr Charles I Berul (George Washington University, Washington, DC) noted the "remarkable" number of patients misdiagnosed with LQTS, the "alarming" number of patients with serious adverse events related to implanted ICDs, and the "shockingly high" number of patients who needed ICD removal. The findings, he continued, emphasize the need for reeducation of physicians about the need for implanting ICDs.

    While no gold standard exists for diagnosing LQTS and current diagnostic tests have limitations, doctors can use "very good" clinical guidelines, genetic testing, detailed clinical history, family history, and diagnostic tests like catecholamine challenge, he proposed.

    Ultimately, though, "the diagnosis should be made by someone familiar with LQTS, as it can be confused with simply having a long QT interval without actually having the syndrome," Berul told heartwire from Medscape. "An individual with syncope and a slightly prolonged QT interval should not automatically be diagnosed with LQTS until complete evaluation is performed."...

    Only 34 patients with confirmed LQTS who were given ICDs (22%) had class I indications for such a device. Of the 13 non-LQTS patients given ICDs, nine had no specific ICD indication. Twelve patients (1% of the total cohort) went on to ICD removal; of those, seven had LQTS and five had been misdiagnosed. Over 5.5 years of follow-up, no patients who had their ICDs removed experienced breakthrough cardiac events...

    They emphasized stepwise treatment of LQTS, with a sufficient trial of beta-blockers and left cardiac sympathetic denervation (LCSD) when indicated before rushing to implantation of an ICD, whose placement should occur as the last resort.

    According to Berul when interviewed, a correct diagnosis of LQTS in youth is particularly important; complicating the diagnosis, symptoms can masquerade as other inherited arrhythmias or benign conditions like fainting with transient QT-interval prolongation.

    "ICD implantation in young patients carries a lifetime of risk, and the decision to implant must be seriously weighed before jumping to the ICD as a safety net," he emphasized. Doctors should carefully weigh the risks and benefits of removal vs simple deactivation of inappropriately placed devices, he added.

    Ackerman declares being a consultant to Boston Scientific, Gilead Sciences, Medtronic, and St Jude Medical and receiving royalties from Transgenomics; disclosures for the coauthors are listed in the article. Berul reports grant support from Medtronic.