Prognostic value of programmed ventricular stimulation for sudden death in selected high risk patients with structural heart disease and preserved systolic function

Abstract

No recommendations exist regarding the proper management of pa-tients with structural heart disease and preserved systolic function,namely post-myocardial infarction (MI) patients with left ventricularejection fraction (LVEF) N40% and dilated cardiomyopathy (DCM)patients with LVEF ≥40% [1]. Between January 2004 and March 2011,we assessed the prognostic role of programmed ventricular stimulation(PVS) in 69 post-MI and 42 DCM patients with preserved LVEF (96males, 65.8 years old, mean LVEF 46 ± 4.5). Specifically, we included62 patients with syncope (n = 36) or presyncope (n = 26) andnon-conclusive 12-lead ECG, Holter monitoring, echocardiographicstudy and tilt table testing as well as 49 asymptomatic patients with ≥1episodes ofnonsustained ventriculartachycardia (NSVT)(≥3 consecu-tive beats at a rate ≥120 bpm) or ≥30 premature ventricularcomplexes/hour on 24-h Holter monitoring. Active ischemia wasexcluded in post-MI patients. DCM diagnosis was based on clinical,echocardiographic and angiographic findings. The study was approvedby the Medical Research Ethics Committee of our Institution and wascarried out in accordance with the Declaration of Helsinki. All subjectswere informed in detail, agreed to participate and signed an informedconsent form.Antiarrhythmics,prescribedbythereferringphysiciansin23patients,were discontinued before the study. Stimulation protocol consisted of upto triple extrastimuli (S2S3S4) delivered at two paced cycle lengths(550 ms and 400 ms) at the right ventricular apex and outflow tract.Extrastimuliwereappliedafterasix-beatdrivetrainwitha2-sinterdrivepause. In DCM patients where no sustained ventricular tachyarrhythmiawas triggered, PVS was repeated after intravenous isoproterenoladministration (1–4 μg/kg/min) [2]. The presence of either sinus and/or atrioventricular node disease was ascertained based on abnormalelectrophysiological parameters [3].When sustained monomorphic VT for post-MI patients or sustainedVT/ventricular fibrillation (VF) for DCM patients was triggered duringPVS, an implantable cardioverter–defibrillator (ICD) was offered andprogrammed on two consecutive zones: an antitachycardia pacing(ATP)zone(VTdetectioncyclelengthof375±40msanddetectionin-terval of 16/16 or 24/24 beats), and an initial shock zone (VF detectioncycle length of 300 ± 30 ms and detection interval of 18/24). Themajor end-points were the incidence of cardiac death and SCD, as wellas the appropriate first ICD activation for implanted patients. Recur-rence of syncope was examined in patients with syncope/presyncopeat baseline.Sustained monomorphic VT was induced in 23/69 (33.3%) post-MIpatients, more frequently in those with NSVT in Holter monitoring(42.5%vs. 20.7%, p = 0.058). ICD was implanted in all induced patientswhile a pacemaker was also implanted in 16 symptomatic post-MI pa-tients with sinus node and/or atrio-ventricular node disease (Fig. 1).Sustained monomorphic VT was induced in 8 and polymorphic VT/VFin 5 of the 42 DCM patients (VT/VF induction rate 31%). ICD wasimplanted in 10/13 induced patients (3 asymptomatic patients deniedimplantation) and a pacemaker in 7 symptomatic patients (Fig. 1).Mean follow-up period was 52.3 months. During that period, 1 in-ducible DCM patient, that denied ICD implant, experienced SCD and 3patients experienced non-cardiac death. None of the non-inducible pa-tientsatbaseline(46post-MIand29DCMpatients)referredrecurrenceor new-onset syncope or pre-syncope or experienced SCD or cardiac