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Presentation Time:
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11/10/2004 9:00:00 AM
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Title:
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Novel Pacing Patterns to Enhance or Suppress T-Wave Alternans in
Patients with Heart Failure
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Keywords:
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Ventricular arrhythmia,Electrophysiology,Pacing
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Author Block:
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John Bullinga, Bryan Piedad, Douglas Holmes, Neil Bernstein, Larry
Chinitz, New York Univ, New York City, NY
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Disclosure Block:
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J. Bullinga, None; B. Piedad, None; D.
Holmes, None; N. Bernstein, None; L. Chinitz,
Endocardial Solutions Inc. B. Research grants, E. Consulting fees or other
remuneration; St. Jude Medical E. Consulting fees or other remuneration;
Medtronic B. Research grants.
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Unlabeled/unapproved:
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There are no unlabeled/unapproved uses of drugs or products
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Background: T-wave alternans
(TWA) is an important clinical tool for ventricular arrhythmia risk
stratification. Current testing of TWA uses exercise or constant pacing
(CP) to elevate the heart rate. These methods do not assess the impact of
the cycle length variation on TWA. We developed two novel pacing patterns
to test the heart’s response to small periodic cycle length changes:
“Resonant pacing” (RP) is designed to augment TWA while “non-resonant pacing”
(NRP) is designed to suppress TWA. We hypothesized that RP would increase
TWA while NRP would suppress TWA in patients with heart failure (HF). Methods:
We evaluated 18 patients with HF (EF 28 ± 9 %, age 70 ± 13 yr) and 3
control patients without HF (EF 56 ± 9 %, age 45 ± 11 yr). Simultaneous
atrial and ventricular pacing was performed with CP (550 ms), RP (repeated
4-beat pattern: 535, 555, 555, 555 ms) and NRP (repeated 3-beat pattern:
545, 555, 555 ms) for 6-minute periods each. TWA with CP was classified
using HearTwave (Cambridge Heart). Patients with determinate tests were
analyzed in response to CP, RP and NRP. The average alternans (mean Valt)
was measured in response to each pacing pattern in the lead with the
largest mean Valt. TWA(+)HF were divided into responders (Grp 1) and
non-responders (Grp 2) defined as a > 25% reduction in mean Valt in
response to NRP. Results: There were 17 patients with determinate
TWA tests: see table below. TWA increased to greater degree in response to
RP relative to CP in patients who were TWA(+) than those who were TWA(-)
(7.9 ± 1.8 μV vs. 16.1 ± 8.5 μV, p = 0.007). 8 of 11 patients who were TWA(+)HF
had suppression of TWA in response to NRP when compared to CP (3.2 ± 3.7 μV vs. 7.5 ± 8.7 μV, p = 0.05). Conclusions: Resonant pacing preferrentially
enhanced TWA in patients who were TWA(+) and may be used diagnostically to
improve identification of TWA. Non-resonant pacing is a new technique that
suppressed TWA in a majority of TWA(+) patients with HF and may have therapeutic
applications.
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Mean Valt (μV) by Group in Response to Pacing Patterns (mean
± st dev)
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Control, n = 3
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TWA(-)HF, n = 3
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TWA(+)HF, Grp 1 n = 8
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TWA(+)HF, Grp 2 n = 3
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Constant Pacing
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1.2 ± 0.5
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0.9 ± 0.4
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7.5 ± 8.7
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10.9 ± 9.3
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Resonant Pacing
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9.1 ± 3.1
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8.9 ± 1.4
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20.4 ± 12.8
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30.0 ± 17.2
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Non-Resonant Pacing
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1.6 ± 0.7
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0.9 ± 0.2
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3.2 ± 3.7
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12.9 ± 7.4
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