Pause-dependent polymorphic ventricular tachycardia during long-term treatment with dofetilide
A placebo-controlled, implantable cardioverter-defibrillator-based evaluation
Alexander Mazur, MD*,
Mark E. Anderson, MD, PhD*,
Sharon Bonney, MD and
Dan M. Roden, MD, FACC*
* Departments of Medicine and Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
Pfizer Central Research, Groton, Connecticut, USA
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Figure 1 An example of pause-dependent polymorphic ventricular tachycardia (VT) from stored implantable cardioverter-defibrillator recordings. The initiation of VT (arrow) starts with a "short-long-short" sequence that is followed by tachycardia with successively different electrogram morphologies. The numbers above the horizontal arrows show duration of RR intervals in milliseconds. Asterisks indicate electrograms with morphologies similar to those in baseline rhythm.
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Figure 2 Two examples of pause-dependent MVT. In both panels, the initiation of MVT (open arrows) is preceded by characteristic "short-long-short" sequences. The numbers above the horizontal arrows show duration of RR intervals in milliseconds. Asterisks in Panel A indicate electrograms with morphologies similar to those in baseline rhythm. Closed arrows in Panel B indicate pacing artifacts followed by the captured ventricular beats. Because only the first four beats of VT in Panel B display polymorphic morphology, the tachycardia was classified as monomorphic.
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