Usefulness of electrocardiographic and echocardiographic parameters for predicting the efficacy of atrioventricular synchronisation during a single lead VDD/R pacing.

BACKGROUND

The VDD/R pacing is accepted as an alternative to DDD/R pacing in patients with atrioventricular conduction block (AVB) and intact sinus node function.

AIM

To determine the relationship between parameters obtained during assessment of the patient for the implantation procedure, using electrocardiographic (ECG) and echocardiographic (ECHO) data, and the effectiveness of AV synchronisation.

METHODS

The study involved a group of 65 patients (43 males, 22 females), aged 66.6 + 12.7 with clinically significant disturbances of AV conduction, who did not reveal symptoms of concomitant abnormalities in sinus node automaticity. Selected ECG and ECHO parameters were studied prior to the implantation procedure. Repeat examinations were done at 3-4 days and at 1, 3, 6 and 12 months after the procedure. The effectiveness of AV synchronisation (PAS) has been estimated by event counter read-out and ECG Holter monitoring.

RESULTS

In 74% patients (subgroup A) synchronisation was highly effective (PAS _ 95%); in the remaining 26% subjects (subgroup B) PAS occasionally fell below 95%. In subgroup B, the P wave was longer than that in subgroup A (105 +/- 16 vs. 92 _ 13 ms; p < 0.05). The dimensions of the right and left heart chambers were greater in subgroup B. Patients in subgroup B had lower ejection fraction (49.4 +/- 13.7% in B vs. 58.2 +/- 11.3% in A) and revealed symptoms of heart failure. The following cut-off values for each echocardiographic and electrocardiographic parameter predisposing to PAS < 95% during VDD/R pacing ('undersensing') were identified: RVEDd > 26 mm, RVESd > 24 mm, LVEDd > 59 mm, LVESd > 37.3 mm, APD LA > 44 mm, SID RA > 52 mm, LMD RA > 48 mm, RAvol> 54 ml, RAarea > 19 cm2, SID LA > 57 mm, LMD LA > 46 mm, EF < 52%, P wave width > 100 ms. Significant predictors of PAS < 95% in the univariate analysis were RVEDd, RVESd, LVEDd, LMD RA, SID RA, RAvol, RAarea, EF, and in the multivariate analysis RVEDd, RVESd, LMD RA, RAarea, EF.

CONCLUSIONS

Selected parameters obtained from ECG (P wave width) and echo examinations are correlated with effective AV synchronisation. Enlargement of the right and left heart chambers (atrial, ventricular), reduction of the ejection fraction and congestive heart failure are associated with impaired AV synchronisation in VDD/R pacemakers. In multivariate analysis, only the higher dimensions of the right ventricle and atrium and the lower ejection fraction of the left ventricle were significantly associated with the PAS < 95%.