Heart Rhythm Society

Heart Rhythm Society

Source:

Zareba W, et al. LBCT04-03. Presented at: Heart Rhythm Society Annual Scientific Sessions; May 6-9, 2020 (virtual meeting).

Disclosures: Zareba reports he received research grants from Biotronik, Boston Scientific, EBR, Gilead and LivaNova and consults for Abbott and ERT.
May 21, 2020
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Tool calculates risk for life-threatening events in long QT syndrome

Source:

Zareba W, et al. LBCT04-03. Presented at: Heart Rhythm Society Annual Scientific Sessions; May 6-9, 2020 (virtual meeting).

Disclosures: Zareba reports he received research grants from Biotronik, Boston Scientific, EBR, Gilead and LivaNova and consults for Abbott and ERT.
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Researchers have developed an online calculator to assess 5-year risk for life-threatening arrhythmic events in patients with long QT syndrome.

Methodology and validation of the University of Rochester long QT syndrome risk calculator was presented at the virtual Heart Rhythm Society Annual Scientific Sessions.

“Patients who are affected by long QT have quite a high risk of cardiac events,” Wojciech Zareba, MD, PhD, FACC, FESC, professor of medicine and director of heart research at the University of Rochester, New York, said during a press conference. “The definition of cardiac events traditionally consists of three parameters: syncopal events, aborted cardiac arrest and sudden death. However, between 20% and 40% of patients with long QT syndrome will have events between age 18 and age 40, which is quite high. When we limit the analysis to life-threatening events — aborted cardiac arrest and sudden death — this number is lower. Between ages 18 and 40, it ranges from 6% to 9% depending on genotype, but is still very high. This is why we want to develop restratification strategies to identify people at high risk.”

The researchers developed a model to predict 5-year risk for aborted cardiac arrest, sudden death or appropriate implantable cardioverter defibrillator shock in patients with long QT syndrome, patterned after the European Society of Cardiology risk model for hypertrophic cardiomyopathy.

To develop the model, Zareba and colleagues analyzed 1,288 patients from Rochester (mean age, 20 years; 56% women; mean QTc, 477 ms) with a single mutation of LQT1, LQT2 or LQT3 and followed them for a mean of 9.8 years. The model included prespecified time-dependent covariates of baseline-corrected QT, age, sex, syncope (never, syncope while off beta-blockers or syncope while on beta-blockers), beta-blocker use and genotype.

The researchers validated the model in a cohort of 1,481 patients with genotyped long QT syndrome from Pavia, Italy (mean age, 21 years; 52% women; mean QTc, 471 ms), who were followed for a mean of 7 years.

Life-threatening event rates were 0.33 per 100 person-years in the Rochester cohort and 0.45 per 100 person-years in the Italy cohort, Zareba said during the press conference.

Using the model, researchers identified combinations of factors that produced low 5-year risk for life-threatening events, defined as less than 4%; moderate risk, defined as 4% to 6%; and risk level that could indicate need for an ICD, defined as higher than 6%.

“The calculator which we created will enable this assessment for every physician,” Zareba said during the press conference. “They will be able to click and enter age, sex, QTc, beta-blocker information and syncope information, and they will get exact 5-year probability of sudden death or aborted cardiac arrest, which are the events we are fearful of. We will release this particular tool very soon.”

The score was not developed for patients with COVID-19 who may get long QT syndrome after treatment with hydroxychloroquine and/or azithromycin, but “we know well the risk factors for drug-induced QT prolongation, which are female sex, older age, lower level of potassium in the blood and concomitant treatment with other drugs for other cardiac conditions,” Zareba said during the press conference. “These typical risk factors we have used should suffice when applied to COVID patients.” – by Erik Swain

Reference:

Zareba W, et al. LBCT04-03. Presented at: Heart Rhythm Society Annual Scientific Sessions; May 6-9, 2020 (virtual meeting).

Disclosure: Zareba reports he received research grants from Biotronik, Boston Scientific, EBR, Gilead and LivaNova and consults for Abbott and ERT.