WALK-IN VT AND PRESERVED EJECTION FRACTION - DO THESE PATIENTS RECEIVE THERAPIES FROM AN ICD?

• Published in: Canadian journal of cardiology Vol. 37; no. 10; p. S50
• Main Authors: Frydman, A, Skanes, A, Gula, L
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01-10-2021
• ISSN: 0828-282X; 1916-7075
• DOI: 10.1016/j.cjca.2021.07.103

Implanted cardioverter defibrillators (ICDs) clearly improve survival in patients with prior cardiac arrest without reversible cause, and in those with sustained ventricular tachycardia (VT) with significantly impaired left ventricular ejection fraction (EF). This ‘secondary prevention’ approach is well supported by evidence from large clinical trials. However, it is not clear from the evidence whether patients with a minimally reduced ejection fraction (35-50%) who experience sustained VT that is hemodynamically tolerated benefit from ICD therapy. ICD implant entails some risk and these devices can malfunction or become infected in a small proportion of patients, making the comparison of benefit to risk clinically important to ICD decision making. We set out to describe a cohort of patients that have received an ICD in London for 'walk-in' VT with preserved ejection fraction, and assess whether they have received therapy from their ICD for ventricular arrhythmias.
We queried our clinical database to identify patients who received an ICD from May 2015 to December 2019 for treatment of a hemodynamically stable episode of VT with ejection fraction minimally impaired at 35-50%. Patient demographics, medications and comorbidities were recorded, along with their history of ICD therapy for ventricular arrhythmias. The timing and nature of ICD therapies was documented. A blanking period was applied to the 7 days after ICD implant to ensure that the presenting episode of VT had subsided was not counted as a follow-up event. Local REB approval was obtained for this project. Among 423 ICDs implanted for secondary prevention during this time period, 64 patients met the enrollment criteria and were included. Average age was 68 (±12) and ejection fraction at time of implant 40%(±4.4). 28 patients (44%) were taking sotalol or amiodarone during follow-up. Over a mean follow-up time of 961 days (±589, range 14-3025) ICD therapy was delivered to 36 (56%) patients. ICD shocks were delivered to 18 (28%) patients over a mean 370 (±347, range 12-1080) days. ATP was delivered to 32 (50%) patients over a mean 239 (±277, range 11-933) days.
ICD therapies are delivered to approximately half of patients with a minimally reduced ejection fraction and an ICD for hemodynamically well tolerated VT, over a period of several years after implant. Guidelines are unclear on ICD indication for these patients due to lack of trial data. Our findings suggest that further study is warranted.