Routine tests should be challenged in cardiology

The need for routine diagnostic tests and procedures needs to be challenged in medical practice, because of continuous pressure to reduce the costs of health care systems. If costs can be minimized by avoidance of routine tests, more sources can perhaps be directed to new advanced diagnostic and therapeutic procedures. This challenge is important particularly in cardiology, because while new diagnostic tests and therapeutic interventions develop rapidly, many institutions and hospitals cannot invest in expensive devices or personnel needed to perform the new tests and interventions. There are many diagnostic tests and procedures in cardiology, such as routine exercise tests, echocardiographic examinations, Holter recordings, pacemaker check-ups etc., that could be challenged. In addition to costs, some of the tests may be uncomfortable for patients. Relatively little evidence-based data are available on the benefits of various routine tests. These tests are often recommended by the manufactures of the therapeutic devices or by some old tradition that is not based on scientific evidence. The study of Brunn et al. has challenged the routine postoperative testing of the defibrillation threshold of implantable cardioverter defibrillators. A large retrospective study shows that the clinical information obtained by routine defibrillation threshold tests is limited. Routine defibrillation threshold measurements provided new information that resulted in therapeutic intervention only in one out of 1000 patients. Most of the cases with high defibrillation thresholds could be predicted by careful clinical evaluation of the patients. Notably, unexpectedly high defibrillation thresholds were obtained in none of the patients who had biphasic implantable cardioverter defibrillators. Frequent problems of high defibrillation thresholds and the need for routine tests were based on the time when monophasic waveforms were used in implantable cardioverter defibrillators. The authors correctly point out that routine postoperative defibrillation thresholds may no longer be needed, because the test itself is unpleasant for the patient and may not be free of complications. However, if there is a clinical suspicion of implantable cardioverter defibrillator dysfunction, e.g. a low safety margin in the intra-operative defibrillation threshold testing or pocket haematoma etc., a repeated test is recommended. The findings and conclusions of this study concur with the results of a smaller prospective, randomized study, which showed that there were no differences in complications and rates of unanticipated hospital admissions between the patients with and without routine defibrillation threshold testing. Of particular note, elimination of routine defibrillation thresholds resulted in savings of $1800/patient after 6 months. The study of Brunn et al. also confirms the previous concept that antiarrhythmic drugs may increase the defibrillation threshold. The authors recommend that the defibrillation threshold should always be tested after the initiation of class I or class III antiarrhythmic drugs. This recommendation is well based on the observations of this and other studies, but I have some concerns that re-testing of the defibrillation threshold after the initiation of antiarrhythmic drugs is not a common practice in all centres. Antiarrhythmic drugs are quite frequently used in implantable cardioverter defibrillator patients, and may also be initiated by experts who are not dedicated to electrophysiology and who are not aware of the potential interactions between the drugs and implantable cardioverter defibrillators. It might be interesting to perform a survey that estimates how often the defibrillation threshold has been tested in clinical practice after the initiation of antiarrhythmic drugs. Of particular note, antiarrhythmic drugs did not cause a failure to defibrillate in any of the patients with biphasic implantable cardioverter defibrillators, which are currently used in all modern devices. As the authors correctly point out, a prospective study would be needed to resolve the question of when the defibrillation threshold should really be re-tested after the initiation of commonly used antiarrhythmic drugs. It may well be that routine tests are not needed in the majority of the patients, and the clinicians should be able to recognize those particular cases, e.g. the patients with a low safety margin, when re-testing is mandatory. It is not certain whether the results and recommendations of these studies can be generalized to common practice in all hospitals, where implantable cardioverter defibrillators are implanted, because the studies have been performed in experienced centres with a high volume of implantable cardioverter defibrillator patients. In the study of Brunn et al. the implantable cardioverter defibrillator failed to defibrillate the patient in six cases, which may be fatal for the patient who has received an expensive life-saving