Tomorrow, Medtronic will begin notifying patients and doctors that they will be voluntarily stop selling their most popular thin defibrillator lead, the Sprint Fidelis (Models 6949, 6930, 6931, 6948), because of a higher-than expected failure rate from lead fractures.
According to Medtronic, over 268,000 of these leads have been implanted worldwide. The Sprint Fidelis lead has had a 97.7% reliability rate, but this has fallen well-below the 99.1% reliability rate of their thicker Sprint Quattro lead. Consequently, they will be withdrawing the Sprint Fidelis defibrillator lead from the market.
For patients already implanted with the lead, it is not expected that leads will require explantation, but Medtronic will be advising careful follow-up of the lead, including changing some warning parameters (so called "Patient Alerts") on their devices in hope of detecting lead fractures earlier. It seems higher-than expected impedances were identified just before lead failure in the rate sensing or defibrillator coil wires from the lead. When a lead fractures, noise is detected by the defibrillator due to intermittent "make-break" connections in the wire(s) of the lead, occassionally leading to shocks delivered at inappropriate times. Should patients experience recurrent unexpected shocks, they should seek evaluation by their implanting physicians immediately. For patients who do not receive such shocks, ongoing monitoring of the lead should occur at regular intervals, and if an impedance change or evidence of noise is detected on the lead, Medtronic is recommending a new lead be inserted.
Since the "Dear Doctor" letter will be issued tomorrow, we'll stand by to see the official recommendations from Medtronic.
Update: Wall Street Journal (subscription required).
Follow-up recommendations also added. -Wes