Title: Effect of Pacing Mode and Cumulative Percent Time Ventricular Paced on Heart Failure and Atrial Fibr
1Effect of Pacing Mode and Cumulative Percent Time
Ventricular Paced on Heart Failure and Atrial
Fibrillation in Patients with Sinus Node
Dysfunction and Baseline QRS Duration lt120
Milliseconds in MOSTA MOST Sub-Study
- Michael O. Sweeney, Anne S. Hellkamp, Arnold J.
Greenspon, Robert Mittleman, John McAnulty,
Kenneth Ellenbogen, Roger Freedman, Kerry L. Lee,
Gervasio A. Lamas, for the MOST Investigators - Circulation 2003, in press
2MOST Sub-Study
- Background
- DDDR pacing preserves AV synchrony and reduces
CHF compared to VVIR pacing in SND. - DDDR pacing results in prolonged QRS durations
(QRSd) due to ventricular desynchronization. - Hypothesis
- DDDR pacing often results in prolonged QRS
duration (QRSd) due to ventricular
desynchronization in patients with normal
baseline QRSd and may increase risk of heart
failure and atrial fibrillation.
Sweeney MO, et al. Circulation 2003, in press
3MOST Sub-Study
- Methods
- Baseline QRSd obtained from 12-lead EKG prior to
IPG implant in MOST (a 2,010 patient, 6-year
randomized trial of DDDR vs. VVIR pacing in SND). - Cumulative time ventricular paced was
determined from stored pacemaker diagnostic data. - Baseline QRSd lt120 ms was observed in 1332
patients 702 were randomized to DDDR 640 to
VVIR.
Sweeney MO, et al. Circulation 2003, in press
4MOST Sub-Study Results
- CumVP was greater in DDDR (90) vs. VVIR (51).
- The rates of CHF hospitalization increased with
CumVP
Sweeney MO, et al. Circulation 2003, in press
5MOST Sub-study Risk of HFH Relative to a DDDR
Patient with Cum VP 0
- Risk of HFH increased between 0 and 40 Cum VP,
but was level at CumVP above 40. - Risk can be reduced to about 2 if ventricular
pacing is minimized.
Sweeney MO, et al. Circulation 2003, in press
6MOST Sub-Study Risk of HFH Relative to a VVIR
Patient with Cum VP 0
- Risk of CHF was constant between 0 and 80 Cum
VP and increased by as much as 2.5-fold when
CumVP exceeded 80. - Risk cannot be reduced regardless of minimization
of ventricular pacing.
Sweeney MO, et al. Circulation 2003, in press
7MOST Sub-Study CHF Risk
- DDDR
- CumVP gt40 was associated with 3 times increased
risk of CHF hospitalization (p0.02). - The risk of CHF hospitalization increased by 54
for each 10 increase in CumVP (Hazard ratio
1.54 1.01, 2.36), p0.05) between 0 and 40. - VVIR
- CumVP gt 80 was associated with 2.6 times
increased risk of CHF hospitalization (p0.007).
- The risk of CHF hospitalization increased by 96
for each 10 increase in CumVP (Hazard ratio
1.96 1.39, 2.77, p0.0001) above 80.
Sweeney MO, et al. Circulation 2003, in press
8MOST Sub-Study
P0.047
Sweeney MO, et al. Circulation 2003, in press
9MOST Sub-Study
P0.0046
Sweeney MO, et al. Circulation 2003, in press
10MOST Sub-studyConclusions CHF
- Higher rates of CHF hospitalization were
associated with higher Cum VP - Cum VPlt10 was associated with the lowest rates
of CHF hospitalization (DDDR 2, VVIR 7). - Cum VP gt90 was associated with the highest
rates of CHF hospitalization (DDDR 12, VVIR
16). - Ventricular pacing in the DDDR mode more than 40
confers a 3-fold increased risk of heart failure
hospitalization but can be reduced to about 2 if
ventricular pacing is minimized.
Sweeney MO, et al. Circulation 2003, in press
11MOST Sub-studyConclusions CHF
- In the VVIR mode, the risk of CHF hospitalization
was level below CumVP ?80 but cannot be
reduced regardless of minimization of ventricular
pacing. This risk is increased by as much as
2.5-fold when CumVP exceeds 80.
12MOST Sub-study AF Risk
Risk of AF increases linearly with CumVP up to
?80-85 in both DDDR and VVIR
Sweeney MO, et al. Circulation 2003, in press
13MOST Sub-study AF Risk
Sweeney MO, et al. Circulation 2003, in press
14MOST Sub-study AF Risk
Sweeney MO, et al. Circulation 2003, in press
15MOST Sub-studyConclusions AF
- Relationship between risk of AF and CumVP was
similar between pacing modes - Risk of AF showed a linearly increasing
relationship with increased CumVP from 0 pacing
up to 80-85 pacing in both pacing modes. - Within this range, the risk of AF increased by 1
for each 1 increase in CumVP (DDDR hazard ratio
1.01 1.004, 1.022 p0.012 VVIR 1.01 1.001,
1.01, p0.025).
Sweeney MO, et al. Circulation 2003, in press
16MOST Sub-StudyOverall Conclusions
- The adverse effects of forced ventricular
desynchronization probably explain the difficulty
in demonstrating a mortality and stroke benefit
with physiologic (DDDR) compared to ventricular
(VVIR) pacing in randomized trials. - Further research is necessary to clarify the role
of electrical unloading of the left ventricle
using minimal ventricular pacing strategies in
SND and normal QRSd.
Sweeney MO, et al. Circulation 2003, in press