Survival improvement

Multicenter Automatic Defibrillator Implantation Trial—Reduce Inappropriate Therapy (MADIT-RIT) confirmed the benefit of optimizing the programming of implantable cardioverter defibrillator (ICD) therapy for the reduction of inappropriate therapy and all-cause mortality, with no impact on the incidence of syncope.1 The true effectiveness of this intervention can be better illustrated by estimating the number needed to treat (NNT)2 (Table 1): to avoid one death, 29 patients had to be programmed using high-rate therapy and 43 with delayed therapy, as compared with conventional programming. This means that physicians may start saving lives (see numbers above for NNT) in primary prevention patients more effectively than avoiding inappropriate shocks (NNT of 59–82 patients, according to the treatment arm) by just programming ICDs less aggressively.

Table 1

Estimation of the number of patients needed to treat using endpoints from the MADIT-RIT trial

Number needed to treat to avoid High-rate therapy vs. conventional therapy Delayed therapy vs. conventional therapy 
One inappropriate therapy 6.2 6.6 
One inappropriate shock 59.2 82.3 
One inappropriate ATP 6.2 7.2 
One appropriate ATP 7.3 6.2 
One death 29.3 43.7 
Number needed to treat to avoid High-rate therapy vs. conventional therapy Delayed therapy vs. conventional therapy 
One inappropriate therapy 6.2 6.6 
One inappropriate shock 59.2 82.3 
One inappropriate ATP 6.2 7.2 
One appropriate ATP 7.3 6.2 
One death 29.3 43.7 

Cost-effective therapy

Comparing the NNT in MADIT-RIT with recent landmark trials reinforces the true impact of the findings in the trial: in the Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation trial, 238 patients had to be treated with apixaban for an average of 1.8 years3 and in the Justification for the Use of Statins in Prevention: an Intervention Trial Evaluating Rosuvastatin trial, 400 patients had to be treated with rosuvastatin 20 mg for an average of 1.9 years,4 to avoid one death from any cause. Unlike these studies, the use of ‘active treatment’ did not lead to any associated costs, since all patients in the MADIT-RIT had been implanted with an ICD. Also, the 1.4 years follow-up accounts for only a small part of the longevity of the device (that should become even longer due to the new programming), clearly underestimating the true impact of the intervention: cost-effectiveness of such ICD programming is obvious. Its impact for quality of life seems also unquestionable.

Anti-tachycardia pacing harm?

The issue of ‘ICD harm’ has been recently addressed in an elegant review by Gasparini and Nisam5 The deleterious haemodynamic effect of ICD shocks has been thought to lead to an adverse prognosis and increased incidence of heart failure.6 Most of the evidence concerning ICD harm has focused on either appropriate7 or inappropriate8 shocks. Furthermore, the effectiveness of the use of a long detection window in primary prevention patients has also been previously demonstrated.9 However, the aim of this programming has always been the prevention of inappropriate shocks or unnecessary shocks (for unsustained ventricular tachycardia). Data from MADIT-RIT may suggest a relationship between anti-tachycardia pacing (ATP) (inappropriate but also appropriate) and mortality. Therefore, the issue concerning ATP (its significance in patient status and if it should be avoided) must be carefully assessed and confirmed.

Transposable?

On the other hand, due to the study design and inclusion criteria, the data from MADIT-RIT cannot be transposed to secondary prevention. Notwithstanding, even in the setting of patients with ventricular tachycardia, a wide variation in detection time was observed in the recent European Heart Rhythm Association Survey published in this journal,10 with 51.1% of centres using a long detection interval (≥5 s or ≥24 impulses) and only 4.4% using a very short detection interval (≤2.5 s or <12–16 impulses). It would therefore be interesting to assess how the duration of detection window impacts on outcomes and if the results of MADIT-RIT may also apply to this completely different population.

Conflict of interest: none declared.

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Author notes

The opinions expressed in this article are not necessarily those of the Editors of Europace or of the European Society of Cardiology.