Dr. Darryl Leong

Transvenous defibrillators (TV-ICDs), implanted in a patient’s heart, may cause or significantly worsen the risk of tricuspid regurgitation (TR) – a potentially serious condition where the heart valve’s flaps don’t close properly, a PHRI study has found.

Six months following device implantation, TV-ICDs increased the risk of TR 7 times over subcutaneous defibrillators (S-ICDs) inserted just under the skin. Severe TR in patients is associated with higher risk of death, heart failure, and atrial fibrillation.

The first randomized clinical trial to test the effect on TR of using TV-ICD versus S-ICD was led by PHRI Scientist Dr. Darryl Leong, specialist in the echocardiographic analysis used in this study.

He presented the results today at Heart Rhythm 2023 in New Orleans, Louisiana. (Download slides – PDF.)

Dr. Jeff Healey

“S-ICDs are less likely to effect TR owing to the absence of a right ventricular lead that can impinge on the tricuspid valve,” says Leong.

The researchers found no detectable difference in the size and function of patients’ right ventricle using the S-ICDs compared to TV-ICD.

“Longer follow-up is needed to determine whether this increase in TR will eventually lead to dilation or dysfunction of the right ventricle,” says PHRI Senior Scientist, Dr. Jeff Healey.

Healey was PI of the main trial, ATLAS S-ICD (Annals of Internal Medicine, presented at Heart Rhythm 2022) which found that compared to TV-ICDs, S-ICDs reduced the rate of major, lead-related complications by 92%.

Like the main trial, this new investigator-initiated study was conducted at 14 Canadian sites funded by Boston Scientific through an unrestricted research grant.

Dr. Kenneth Stein

“The ICD is the most effective therapy that we have to prevent death due to cardiac arrhythmia, however it is an invasive therapy which can cause adverse effects.” says Dr. Kenneth Stein of Boston Scientific. Over the last 15 years, Boston Scientific and PHRI have worked together to reduce these adverse effects of ICD therapy, while preserving its established benefit.”

HRS 2023 presentation (PDF)

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