title: Analysis of intracardiac electrograms showing monomorphic ventricular tachycardia in patients with implantable cardioverter-defibrillators.
abstract: Ventricular tachycardia (VT) initiation and its relation to various clinical factors was studied by reviewing intracardiac electrograms from patients with implantable cardioverter-defibrillators. Events were divided into (1) sudden onset without preceding ventricular premature complexes (VPCs), (2) extrasystolic onset with VPCs, or (3) paced, depending on the type and morphology of the last 5 beats before initiation of VT. Prematurity index, sinus rate, cycle length, and presence of short-long-short sequence for each episode was noted. A total of 268 episodes of VT among 52 patients were analyzed. Extrasystolic initiation was the most frequent pattern (177; 66%) followed by sudden onset (75; 28%) and paced (16; 6%). Among extrasystolic onset, 99 episodes (56%) were due to multiple VPCs and 149 episodes (84%) had different VPC morphology than the subsequent VT. Among pacing-induced VT, 13 of 16 episodes were due to inappropriate pacing due to undersensing of prior R waves. Sudden-onset episodes were slower (mean cycle length 383+/-97 ms) than extrasystolic (mean cycle length 336+/-88 ms, p = 0.002) and paced (mean cycle length 313+/-85 ms, p = 0.01) onset. Patients in the sudden-onset group had better left ventricular ejection fraction (33+/-15%) than the extrasystolic (29+/-11%, p<0.001) and paced (28+/-14%, p<0.01) groups. Extrasystolic onset with multiple, late coupled VPCs was the most common pattern of VT initiation and was associated with lower ejection fraction. Sudden-onset initiation was more common with better preserved systolic function.
authors.affiliation: New England Cardiac Arrhythmia Center, Boston, Massachusetts, USA.
authors.forename: M
authors.initials: M
authors.lastname: Saeed
authors.forename: M S
authors.initials: MS
authors.lastname: Link
authors.forename: S
authors.initials: S
authors.lastname: Mahapatra
authors.forename: M
authors.initials: M
authors.lastname: Mouded
authors.forename: D
authors.initials: D
authors.lastname: Tzeng
authors.forename: V
authors.initials: V
authors.lastname: Jung
authors.forename: R
authors.initials: R
authors.lastname: Contreras
authors.forename: C
authors.initials: C
authors.lastname: Swygman
authors.forename: M
authors.initials: M
authors.lastname: Homoud
authors.forename: N A
authors.initials: NA
authors.lastname: Estes
authors.forename: P J
authors.initials: PJ
authors.lastname: Wang
mesh_terms: D000368:Aged; D005117:Cardiac Complexes, Premature / Q000150:complications; D002304:Cardiac Pacing, Artificial; D016022:Case-Control Studies; D017147:Defibrillators, Implantable; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*