DATAS: The Dual Chamber & Atrial Tachyarrhythmias Adverse Events Study (DATAS)

The Dual Chamber & Atrial Tachyarrhythmias Adverse Events Study (DATAS) was designed to analyze the ability of dual chamber ICDs, to reduce clinically significant adverse events as compared to single chamber ICD in a non selected population with conventional indication of ICD implantation.

Single chamber (SC) implantable cardioverter defibrillators (ICDs) have several limitations that might be relevant during follow up, like atrial pacing requirements, inadequate therapies, sustained atrial tachyarrhythmias and difficulties to achieve an accurate diagnosis of the arrhythmia. Dual chamber (DC) ICDs offer an attractive rationale solution, although controversy remains if the costs and complexity of the implants offer a real clinical advantage. The DATAS is a, prospective, multicentre, randomized, open labelled study, with three arms (two of them cross-over and the third parallels the other two) The primary objective of this trial is to determine whether use of Dual Chamber ICD (DDED-DDDR NASPE/BPEG Defibrillator/Pacemaker Codes) results in a significant decrease in the number of primary end points. The primary end point is a composite comprising four so-denominated "Clinically Significant Adverse Events (CSAE)": all-cause mortality invasive intervention, hospitalization (>24 h) or prolongation of hospitalization due to cardiovascular cause inappropriate shocks (two or more episodes with inappropriate shocks) sustained symptomatic atrial tachyarrhythmias that (a) require urgent termination or (b) last more than 48 h leading to therapeutic intervention. Secondary objectives are: Number of each of the components of the CSAE. Arrhythmia related: atrial tachyarrhythmia (AT), frequency and burden, ventricular tachyarrhythmia frequency and burden number of appropriate shocks, number of inappropriate shocks, need for reprogramming, need for medication/Radiofrequency Ablation (RFA) for arrhythmia control, pacemaker syndrome and development of dual chamber pacing indication. Cardiovascular related: New York Health Association (NYHA) functional class, exercise capacity, left ventricular ejection fraction (LVEF), reduction of medication (diuretics.). Quality of life: evaluated by the SF-36, Minnesota living test, with heart failure and Symptom Checklist instruments.

Main outcome was defined as the CSAE-score during follow-up: CSAE-score rate. We assigned death as the worst outcome during the entire study; and premature cross-over as the main failure of the assigned therapy. So each CSAE was assigned 1 point but (a) death was assigned a score equal to the max number of CSAE in any individual patient in the entire study +1, and (b) premature authorized crossover was given a score equal to the max number of CSAE in any individual patient in that period. Thus, main outcome was defined as the CSAE-score over length of follow-up resulting in a CSAE-score rate.

The primary endpoint is a composite of 5 pre-determine Clinical Significant Adverse Events (CSAE): (1) all-cause mortality, (2) invasive intervention due to Cardiovascular cause, (3) hospitalization (>24h) or prolongation of hospitalization due to CV, (4) inappropriate shocks: two or more episodes with inappropriate shocks, (5) sustained symptomatic ATs that (a) require urgent termination or (b) lasted more than 48 h leading to therapeutic intervention. Number of each of the components of CSAE, counts the number of events for each pre-determined level.

Inclusion Criteria: Meet the Class I implantation criteria for single chamber implantable cardioverter defibrillator according to the guidelines (ACC/AHA). Exclusion Criteria: Permanent atrial fibrillation Patients without structural heart disease Patient meets implantation criteria for dual-chamber pacing (symptomatic sinus node disease, all 2nd Atrio-Ventricular (AV) block [except asymptomatic Mobitz I] and all 3rd degree AV block ). Patient with previous system implanted (ICD or pacemaker). Patients with biventricular stimulation or re-synchronization. Patient has a mechanical right heart valve. Patient has medical conditions that would preclude the testing required by the protocol, or limit study participation. Patient is unwilling or unable to cooperate or give written informed consent, or the patient is a minor and legal guardians refuse to give informed consent. Patient is or will be inaccessible for follow-up at the study center. Patients who are enrolled or planning to enroll in other clinical trials during the clinical study.

Quesada A, Almendral J, Arribas F, Ricci R, Wolpert C, Adragao P, Cobo E, Navarro X; DATAS Investigators. The DATAS rationale and design: a controlled, randomized trial to assess the clinical benefit of dual chamber (DDED) defibrillator. Europace. 2004 Mar;6(2):142-50. doi: 10.1016/j.eupc.2003.11.011.

Almendral J, Arribas F, Wolpert C, Ricci R, Adragao P, Cobo E, Navarro X, Quesada A; DATAS Steering Committee; DATAS Writing Committee; DATAS Investigators. Dual-chamber defibrillators reduce clinically significant adverse events compared with single-chamber devices: results from the DATAS (Dual chamber and Atrial Tachyarrhythmias Adverse events Study) trial. Europace. 2008 May;10(5):528-35. doi: 10.1093/europace/eun072. Epub 2008 Apr 7.

Ricci RP, Quesada A, Almendral J, Arribas F, Wolpert C, Adragao P, Zoni-Berisso M, Navarro X, DeSanto T, Grammatico A, Santini M; DATAS study Investigators. Dual-chamber implantable cardioverter defibrillators reduce clinical adverse events related to atrial fibrillation when compared with single-chamber defibrillators: a subanalysis of the DATAS trial. Europace. 2009 May;11(5):587-93. doi: 10.1093/europace/eup072.

Hadid C, Almendral J, Ortiz M, Schwab JO, Janko S, Mischke K, Arribas F, Wolpert C, Ricci R, Adragao P, Cobo E, Navarro X, Quesada A. Incidence, determinants, and prognostic implications of true pleomorphism of ventricular tachycardia in patients with implantable cardioverter-defribillators: a substudy of the DATAS Trial. Circ Arrhythm Electrophysiol. 2011 Feb;4(1):33-42. doi: 10.1161/CIRCEP.110.957068. Epub 2010 Nov 13.