The impact of paced QRS duration on the expression of genes related to contractile function of the left ventricle in chronically paced patients from the right ventricular apex.

BACKGROUND

Right ventricular (RV) apex has proven to induce abnormal left ventricular (LV) activation pattern leading to pacing-induced cardiomyopathy (PICM) in a substantial percentage of paced patients. This study assessed the impact of paced QRS duration on the expression in the peripheral blood of sarcoplasmic reticulum calcium ATPase (SERCA) and investigated whether its width is related to the extend of LV remodelling.

METHODS

We enrolled 52 consecutive patients with preserved ejection fraction (EF) who underwent pacemaker implantation for bradycardic indications. Group A consisted of 24 patients paced for atrioventricular conduction disturbances with QRS = 142 ± 12 ms post-implant and group B of 28 patients paced for sinus node disease with QRS = 94 ± 2%ms post-implant. mRNA levels of SERCA were assesed at implantation, 3, 6 and 12 months follow-up, while echocardiographic parameters at implantation, 1, 2 and 4 years.

RESULTS

In group A, mRNA levels of SERCA decreased significantly at 3 months and remained low at 6 and 12 months' follow-up and were associated to the deterioration of LV function and geometry. Paced QRS duration was associated to both the alteration in the expression of SERCA and to the extend of LV remodelling. In group B no statistically significant change was demonstrated.

CONCLUSIONS

Permanent RV pacing in patients with preserved EF and wide QRS post-implant is associated with a significant reduction of mRNA levels of SERCA. Paced QRS duration is associated to alterations in the expression of SERCA which precede adverse LV remodelling.