Shock as a Determinant of Poor Patient-Centered Outcomes in Implantable Cardioverter Defibrillator Patients: Is There More to It Than Meets the Eye?

The medical benefits of the implantable cardioverter defibrillator (ICD) are well established, but ICD shocks are known to influence patient-centered outcomes. In this viewpoint, we examine the strength of the evidence as found in primary and secondary prevention trials that used quality of life as an outcome, and compare the influence of ICD shock with other factors (e.g., heart failure and psychological factors) as determinants of outcomes, with a view to providing recommendations for clinical practice and future research. Based on the large-scale primary and secondary prevention trials (i.e., CABG-PATCH, CIDS, AVID, AMIOVIRT, SCD-HeFT, MADIT-II, and DEFINITE), evidence for an association between ICD shocks and quality of life is mixed, with some indication that the influence of shocks may depend largely on the interval between shocks and assessment of quality of life. In order to improve the clinical management of ICD patients, we need to adopt a more rigorous and standardized methodology in future studies in order to be able to draw firm conclusions about the impact of ICD shocks on individual patients. We also need to acknowledge that the impact of shocks on psychological functioning and quality of life may not be as straightforward as previously assumed. Given that programming of the ICD is changing, leading to fewer shocks and improved quality of life, it may be timely to also examine the influence of other determinants (e.g., heart failure progression and the patient's psychological profile) of patient-centered outcomes both in research and in clinical practice. (PACE 2010; 33:1430-1436).