Key result
First-degree AV-block linked to ~31% higher risk of death, stroke, or HF hospitalization.
Why the study?
The prognostic impact of first-degree AV-block in patients with sinus node dysfunction and the impact of pacing in this setting were not known.
Does baseline first-degree AV-block predict adverse clinical outcomes in patients with sinus node dysfunction requiring pacing?
RCT (n=2,010)
randomized
Does baseline first-degree AV-block predict adverse clinical outcomes in patients with sinus node dysfunction requiring pacing?
Hazard Ratio: 1.31 (95% CI 1.06–1.61)
p-value: p=0.013
In patients with sinus node dysfunction requiring pacing, baseline first-degree AV-block is an independent predictor of increased risk for death, stroke, or heart failure hospitalization, a risk not eliminated by DDD-R or VVI-R pacing.
First-degree AV-block independently predicts worse outcomes in paced SND patients; leaves open whether alternative pacing strategies improve prognosis.
BACKGROUND: Patients with a pacing indication and first-degree atrioventricular (AV)-block pose a clinical challenge. The prognostic impact of first-degree AV-block in patients with sinus node dysfunction and the impact of pacing in this setting are not known. METHODS: In the Mode Selection Trial (MOST), 2,010 patients with sinus node dysfunction were randomized to either dual-chamber (DDD-R) or ventricular (VVI-R) pacing and followed for a median of 33 months. We report on clinical outcomes in patients with first-degree AV-block (PR interval > 200 ms) compared with patients who had a normal PR interval at baseline. RESULTS: Patients with first-degree AV-block (n = 378) were older (median [Q1, Q3]; 76 [70, 82] years vs 73 [66, 79] years, P< 0.0001), more often male (57% vs 49%, P = 0.0049), and had more comorbidity, such as hypertension (66% vs 60%, P = 0.034) and heart failure (24% vs 17%, P = 0.0050) than patients with normal AV-conduction (n = 1,159). In multivariable analyses, patients with first-degree AV-block were at greater risk of death, stroke, or heart failure hospitalization (hazard ratio [HR] 1.31, 95% confidence interval [CI] 1.06-1.61, P = 0.013). A trend towards a higher incidence of atrial fibrillation was seen (HR 1.24, 95% CI 0.98-1.55, P = 0.069). No significant interactions between pacing arm and prolonged versus normal PR were found for any endpoint, and hazard ratios were consistent across subgroups. CONCLUSIONS: First-degree AV-block is associated with more advanced disease but is still an independent predictor of poor clinical outcome. Neither DDD-R nor VVI-R pacing, as employed in MOST, eliminate the negative effects associated with first-degree AV-block.
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Holmqvist et al. (2014) conducted an RCT in Sinus node dysfunction (n=2,010). First-degree AV-block (PR interval > 200 ms) vs. Normal PR interval was evaluated on Death, stroke, or heart failure hospitalization (HR 1.31, 95% CI 1.06-1.61, p=0.013). First-degree AV-block increased the risk of death, stroke, or heart failure hospitalization compared to a normal PR interval in patients with sinus node dysfunction (HR 1.31; 95% CI 1.06-1.61; P=0.013).
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