Mechanical Remodeling of the Left Atrium After Loss of Atrioventricular Synchrony
Key result
Chronic VVI pacing decreased left atrial appendage velocity from 82.4 to 42.1 cm/s (P<0.01) and induced spontaneous echo contrast in 19% of patients, which reversed after restoring AV synchrony.
Why the study?
Does chronic VVI pacing cause mechanical remodeling of the left atrium compared to DDD pacing in patients with permanent pacemakers?
Population
32 patients with permanent pacemakers (n=21 randomized to VVI, n=11 randomized to DDD)
Comparison
Chronic VVI pacing for 3 months, followed by… vs Chronic DDD pacing (AV synchrony) for 3 months
Design
RCT, prospective randomized comparison
Follow-up
3 months
Authors
Discussion
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Implication
Chronic VVI pacing may elevate thromboembolic risk via atrial remodeling; leaves open whether DDD mode prevents this in broader populations.
Study Design
Type
RCT (n=32)
Structured PICO
Does chronic VVI pacing cause mechanical remodeling of the left atrium compared to DDD pacing in patients with permanent pacemakers?
P
Population
32 patients with permanent pacemakers randomized to chronic VVI or DDD pacing for 3 months.
I
Intervention
Chronic VVI pacing (loss of AV synchrony) for 3 months, followed by programming to DDD pacing for an additional 3 months
C
Comparator
Chronic DDD pacing (AV synchrony) for 3 months
O
Outcome
Left atrial appendage (LAA) function (velocity and fractional area change) and presence of spontaneous echo contrast (SEC) determined with transesophageal echocardiography (TEE) at 3 monthssurrogate
Main Result
Absolute Event Rate: 42.1% vs 79.6%
p-value: p=<0.01
Chronic loss of AV synchrony from VVI pacing induces reversible mechanical remodeling of the left atrium, providing a mechanistic explanation for the increased thromboembolic risk compared to AV sequential pacing.
Cite This Study
Sparks et al. (1999) conducted an RCT in Permanent pacemakers (n=32). VVI pacing vs. DDD pacing was evaluated on Left atrial appendage (LAA) velocity (p=<0.01). Chronic VVI pacing decreased left atrial appendage velocity from 82.4 to 42.1 cm/s (P<0.01) and induced spontaneous echo contrast in 19% of patients, which reversed after restoring AV synchrony.