Atrial tachyarrhythmia burden modelling by some electrophysiological parameters in pacemaker-recipient patients with Brady-Tachy syndrome.

Aims: (1) To correlate atrial tachyarrhythmia (AT) burden of pacemaker-recipient Brady-Tachy syndrome (BTS) patients with a number of diagnostics-derived parameters after 1 month of DDD pacing; (2) to asses whether the activation of atrial overdrive or conventional rate-responsive pacing may affect relevant variables and their correlation.

Methods And Results: After 1 month of DDD pacing, rate-responsive function or persistent atrial overdrive was randomly activated for 3 months, in 92 BTS patients. Some pacemaker diagnostics parameters collected at 1- and 4-month follow-ups were included in multiple linear regression models, whose dependent variable was the Log transformation of AT burden and compared. With 1-month data, the only variables significantly correlating with Log AT burden were average (with a regression coefficient estimate of -0.07, P=0.02) and standard deviation (0.10, P=0.007) of atrial rate, mean premature atrial contraction (PAC) coupling interval (CI) (-0.005, P=0.001), frequency of PACs with CI<500 ms (1.30, P<10(-6)). Atrial pacing percentage (APP) and ventricular pacing percentage (VPP), PACs with CI>500 ms did not significantly correlate. Four-month data largely confirmed these results, except that in DDDR atrial rate average and standard deviation no longer correlated. Overdrive significantly increased APP and reduced PACs with CI>500 ms.

Conclusion: AT burden showed significant dependence in DDD and during overdrive on atrial rate average and standard deviation. Highly premature PACs always significantly correlated with AT burden. Though increasing APP, which unexpectedly never correlated, overdrive could only reduce less premature PACs.