Mauro Villani, Sabrina Iannuzzi,
Gino Iannucci, Federico Caruso*, Cataldo Pisicchio, Daniela Imperiale, Giacinto
Baciarello.
Arrhythmia Control Unit, La Sapienza University,
*MANFRI srl, Rome, Italy
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The signal averaged ECG (SAECG) could be useful to
detect patients (pts) at risk of paroxysmal atrial fibrillation (PAF) but prospective
studies for clinical utilization of SAECG are necessary. For these reasons we have studied
a group of 46 pts, mean age 63.8 ± 11.5 years, with documented episodes of PAF to observe
if it is possible to identify pts at risk of relapse into PAF, using SAE in the time (TD)
and frequency domain (FD). On the grounds of the clinical conditions and of the frequency
of episodes of PAF, 24 pts underwent antiarrhythmic drugs, group PAF-A, while 22 pts did
not, group PAF-NA. All pts also underwent SAECG after 3 and 6 months. The P-wave duration
(Pd) and the root mean square of the last 40, 30 20 and 10 ms (RMS40, RMS30, RMS20, RMS10)
have been calculated in the TD. Two quantitative indexes, absolute (AB) and normalized
(N), have been calculated on the three leads and the total values of each index (ABT and
NT) have been also calculated in the FD.
In the time domain our results seem to confirm that the P-wave in both groups, PAF-A
and PAF-NA, is significantly prolonged (dP ms 111.0 ± 11.6 vs 89.7 ± 9.7; p < 0.0001)
and presents a lower amplitude of the end portion (RMS20 µV 2.5 ± 1.3 vs 3.2 ± 1.6, p
< 0.02; RMS10 µV 1.6 ± 0.9 vs 2.3 ± 1.6, p < 0.01), with respect to a control
group of 40 healthy subjects of similar age. Therefore, these parameters seem to be not
useful to predict the relapse. On the contrary, the FD seems to be useful to predict the
relapse of PAF with a total predictive accuracy of 81%. In fact the ABS, at the third
month, was higher in 87% of PAF-A that relapsed into the following months and was lower in
84% of PAF-A who did not, with respect to basic conditions (p < 0.005) (mean value:
4086.2 ± 470.7 vs 3575.3 ± 545.6; p < 0.02; 3314.8 ± 939.3 vs 3943.4 ± 859.5; p
< 0.02). Similar results were also obtained in the PAF-NA. Our results seem to
demonstrate that higher frequency components could be the expression of a greater
electrical instability and can better identify pts at risk of relapse into PAF.
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