ΣΤ Στρογγυλό τραπέζι : Απινιδωτές-CRT Απινιδωτές στην πρωτογενή πρόληψη. Έφθασε ο καιρός για αναθεώρηση των ενδείξεων? Πολυχρόνης Δηλαβέρης, MD, PhD, FESC Nucleus Member, e-cardiology WG at the ESC Διευθυντής Ε.Σ.Υ. A Πανεπιστημιακή Καρδιολογική Κλινική, Ιπποκράτειο Νοσοκομείο, Αθήνα No conflict of interest to declare
Sudden Cardiac Death Prevention One of the most significant indicators of SCD risk is survival of a previous episode, and the implantable cardioverter defibrillator (ICD) is an established therapy for secondary prevention. The AVID Investigators. N Engl J Med 1997;337:1576 1583. Connolly SJ, et al. Circulation 2000;101:1297 1302. Kuck KH, et al. Circulation 2000;102:748 754. For primary prevention, reduced left ventricular ejection fraction (LVEF) is the most widely deployed risk factor and is the principal determinant in assessing eligibility for prophylactic ICD therapy. Bardy GH, et al. N Engl J Med 2005;352:225 237. Moss AJ, et al. N Engl J Med 2002;346:877 883. However, this strategy may have only modest impact on the incidence of SCD, because most cases occur in individuals with preserved LV systolic function.
HRS/ACC/AHA Expert Consensus Statement on the Use of Implantable Cardioverter-Defibrillator Therapy in Patients Who Are Not Included or Not Well Represented in Clinical Trials Figure 1. Survival curves for the ICD-only primary prevention trials in patients with cardiomyopathy (CM) due to coronary artery disease (CAD) or acute myocardial infarction (MI), heart failure, or nonischemic CM. All curves represent mortality/survival. MADIT... Fred M. Kusumoto, et al. Heart Rhythm 2014;7:1270-1303.
Limitations of Ejection Fraction (EF) for Prediction of Sudden Cardiac Death (SCD) EF dependence on loading conditions and heart rate limit its accuracy, EF measurement reproducibility in clinical practice is low and significant alterations can be observed during the disease course, due to progressive remodeling, or secondary to treatment. EF is a powerful predictor for total mortality, being, in fact, more robustly related to total cardiac mortality than to SCD. Buxton AE, et al. J Am Coll Cardiol. 2007; 50(12):1150-1157. Mäkikallio TH, et al. Eur Heart J. 2005; 26(8):762-769. Population-based analyses of cardiac arrest have shown that SCD cases with significantly depressed EF constitute only a minority of SCD-cohorts. For example, in the Oregon Sudden Unexpected Death Study EF was severely reduced in 30%, mildly to moderately reduced in 22%, and normal in 48% of sudden unexpected death cases. Stecker EC, et al. J Am Coll Cardiol. 2006;47(6):1161-1166. Likewise, in the Maastricht Circulatory Arrest Registry, among patients with cardiac arrest and diagnosed heart disease, 26% had overt heart failure; of these, 48% had EF less than 30%. However, from the remaining 74% of patients without heart failure, only 9% had EF less than 30%. Gorgels AP, et al. Eur Heart J. 2003; 24(13):1204-1209.
N Engl J Med. 2016 Sep 29;375(13):1221-30.
Utility of current risk stratification tests for predicting major arrhythmic events after myocardial infarction Figure 1. Receiver-operating characteristic (ROC) curves for the five tests evaluated in the study. The curves were generated using the approach of Moses et al. (17). AECG = ambulatory electrocardiography; ECG = electrocardiogram. James J Bailey, et al. JACC 2001
Long-Term Arrhythmia-Free Survival in Patients With Severe Left Ventricular Dysfunction and No Inducible Ventricular Tachycardia After Myocardial Infarction Zaman S, et al. Circulation. 2014;129:848-854
Techniques incorporating functional parameters, depolarization abnormalities, repolarization abnormalities, and arrhythmic markers provide only modest risk stratification for SCD in patients with NIDCM. Goldberger JJ, Subačius H, Patel T, Cunnane R, Kadish A. Sudden Cardiac Death Risk Stratification in Patients with Nonischemic Dilated Cardiomyopathy. J Am Coll Cardiol. 2014 ;63:1879 89.
J Am Heart Assoc. 2015;4:e002149
Protein Biomarkers Identify Patients Unlikely to Benefit From Primary Prevention Implantable Cardioverter Defibrillators Findings From the Prospective Observational Study of Implantable Cardioverter Defibrillators (PROSE-ICD) In this large cohort study of stable patients with systolic heart failure who were candidates for primary prevention ICD implantation, serum biomarkers did poorly in predicting the likelihood of an appropriate ICD shock (primary end point). However, they did identify patients at increased risk of dying (secondary end point) without experiencing an appropriate ICD shock. Cheng A, et al. Circ Arrhythm Electrophysiol. 2014;7:1084-1091
CONCLUSIONS SCD is not a single entity but rather is related to a variety of factors including coronary anatomy, degree of myocardial ischemia, left ventricular dysfunction, presence of scar/arrhythmic substrate, and genomic factors. Consequently, it is unlikely that any single test will be able to adequately risk stratify which patients with CAD are at greatest risk of SCD and warrant insertion of an ICD for primary prevention. Most of the available tests are not featured in current guidelines for selection of ICD recipients, which are based mainly on the results of prospective multicenter trials. Therefore, as with many other aspects of modern medicine, clinicians need to find the right balance between clinician-patient dialogue, evidence-based medicine, and the adherence to current guidelines.