Analysis of intracardiac electrograms showing monomorphic ventricular tachycardia in patients with implantable cardioverter-defibrillators

Mohammad Saeed, Mark S. Link, Srijoy Mahapatra, Majd Mouded, David Tzeng, Vivian Jung, Robert Contreras, Craig Swygman, Munther Homoud, N. A. Mark Estes, Paul J. Wang

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57 Scopus citations


Ventricular tachycardia (VT) initiation and its relation to various clinical factors was studied by reviewing infracardiac 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 shorf-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.

Original languageEnglish (US)
Pages (from-to)580-587
Number of pages8
JournalAmerican Journal of Cardiology
Issue number5
StatePublished - Mar 9 2000

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine


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