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Controversial issues: implantable cardioverter-defibrillator implantation

Session presentations
  • Defibrillation testing should be routinely performed at the time of implantable cardioverter-defibrillator implantation.: Pro. Presented by J Healey (Hamilton, CA)See the slides 1See the slides 2
  • Defibrillation testing should be routinely performed at the time of implantable cardioverter-defibrillator implantation.: Contra. Presented by F Arribas (Madrid, ES)See the slides 1See the slides 2
  • Warfarin should be stopped before implantable cardioverter-defibrillator implantation.: Pro. Presented by A Da Costa (Saint-Etienne, FR)See the slides 1See the slides 2
  • Warfarin should be stopped before implantable cardioverter-defibrillator implantation.: Contra. Presented by C Wolpert (Ludwigsburg, DE)See the slides 1See the slides 2

This interesting session included 2 debates.

The first debate dealt with the need to routinely perform a defibrillator threshold test (DFT) test at the time of ICD implantation. Dr. Jeff Healey argued in favor of routine testing whereas Dr Fernando Arribas defended testing only in specific cases. Dr Healey pointed out a number of reasons why performing a DFT test is useful. It will ensure integrity of the circuit, ensure proper sensing, and also ensure success of defibrillation. On top of that, DFT testing was performed in all ICD trials, is included on product labeling and is still considered the standard of care. However, this practice is under debate because it takes time, requires additional resources like anesthesia, has a small but still not negligible risk of complications, and it has been argued that induced VF does not necessarily reflect what happens during a spontaneous episode of VF.

Dr. Healey defended the need for testing, presenting several data from the literature showing that there are around 10% of patients in whom the first shock during arrhythmia is not effective. He also presented data demonstrating that the risk of complications nowadays has been overstated and the incremental costs are small.

Dr Arribas agreed with the point that there is not much evidence in favor of either of the 2 positions, but he defended performing DFT testing only in specific patients with increased risk for high threshold. He showed that there is a clear tendency in clinical practice in favor of not performing the test. In fact, the SIMPLE study (Shockless implant evaluation) that is conducted by Dr. Healey is expected to answer this question in a large randomized study. The SIMPLE study is designed to recruit 2500 patients and the follow up will be completed in October 2013 (Am Heart J 2012, 164 (2): 146). While awaiting the results, either of the 2 positions can be defended, but still, DFT testing represents the standard of care.

The second debate was devoted to the anticoagulation policy in patients at high risk for embolic events who underwent device implantation.

Dr. Da Costa defended the position to stop warfarin and bridge to heparin, whereas Dr. Wolpert defended the position that the implant can be safely done under warfarin provided that the INR is around 2.5%. Dr. Da Costa referred to several studies that have not found differences in the risk of thromboembolic events or bleeding using either of the 2 strategies. However, most studies were small and retrospective. In a prospective randomized study, Tolosana et al (Eur Heart J 2009) showed that there were no differences in hemorrhagic risk, but the hospital stay was significantly shortened. A recent meta-analysis by Ghanbari et al. (Am J Cardiol 2012) found a decreased risk of hemorrhage in the warfarin maintenance group as compared to the heparin bridging, without an increased risk of thromboembolic events.

Dr. Wolpert argued also that data in the literature support the approach not to stop warfarin. On the other hand, excess dosing of heparin often occurs in patients with impaired renal function. He also drew our attention to the definition of high risk. New AF guidelines consider that paroxysmal AF with low CHADS-VASC should not be defined as high risk, and therefore, warfarin may be stopped before surgery and restarted after surgery.

In summary, it seems that continuing with warfarin may be better compared to bridging to heparin in patients who underwent a device implant and have a high risk of thromboembolic event. Finally, the presenters discussed the policy to follow in patients with dual antiplatelet therapy. They recommended avoiding intervention while being under dual antiplatelet therapy. However, it was recognized that is sometimes unavoidable. In patients who suffer bleeding during intervention, the placement of aspiration drainage could be of help.




Controversial issues: implantable cardioverter-defibrillator implantation

The content of this article reflects the personal opinion of the author/s and is not necessarily the official position of the European Society of Cardiology.