Prof. Alessandro Capucci
Defibrillation threshold (DFT) testing should no longer be performed. The 2 speakers debated respectively in favour of or against DFT.
Dr Viskin advocated NOT performing DFT and outlined how:1) the vast majority of the implanted pts will not have VF, and VT is reported to occur in 40%; 2) induced VF differs from spontaneous VF and the induced form has a success rate higher than the spontaneous; 3) ICD testing is anyway limited to 2 VF induction; 4) in the study SCD-HeFT, the pts implanted despite a DFT higher than 30 joules had similar survival to those with a proper DFT value. Other points raised included the fact that from the literature, there is a trend towards a higher mortality in pts with DFT testing (complication rate 0.18%). Dr Goette on the other hand underlined how the death rate with DFT is only 0.016% (Healy J. JCE 2010). Meanwhile shock failure reached 20% of the tests. There is also a legal issue when a patient suddenly dies after an ICD was implanted without performing any DFT. Moreover, the Altitude study showed that DFT did not negatively affect mortality by using the 1st shock at low energy level.
In conclusion, we must say that we are currently at a point where DFT is not considered a must any more, as it was in the 90s, and is not to be extensively performed. However, especially in patients with very low ejection fraction and high likelihood of spontaneous VF, it is still of great value. Only prospective trials may eventually report in favour of definitely abolishing DFT completely. On the second issue, it came out that the non functional leads should be removed if the patient is symptomatic for infections or venous thrombosis related to the leads or in case of interaction between two endocardial defibrillation leads. It has to be taken into account that even if the mortality rate of leads extraction is very low, there is a certain rate of complications and also a learning curve in laser employment (at least 30 procedures).
Controversies in implantable cardioverter-defibrillator therapy
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