Association of corrected QT dispersion with symptoms improvement in patients receiving cardiac resynchronization therapy

Abstract

Cardiac resynchronization therapy (CRT) is theoretically expected to affect repolarization as well as depolarization. We studied the effects of CRT on corrected QT (QTc) dispersion in association with symptomatic improvement. QTc dispersion was analyzed in 26 consecutive patients (67 +/- 6 years old, 18 men and 8 women) who underwent CRT. CRT responders and nonresponders were defined as patients showing and not showing > or = 1 class New York Heart Association symptomatic improvement 3 months after CRT, respectively. QTc interval, QRS width, and QTc dispersion were measured automatically from digital data using an analyzing system. There were 18 CRT responders and 8 nonresponders among the patients. CRT responders showed significantly larger QTc dispersion than CRT nonresponders before CRT (102 +/- 26 vs 40 +/- 12 ms, P < 0.01). A significant decrease in QTc dispersion by CRT was observed in responders (102 +/- 26 to 52 +/- 15 ms, P < 0.01). In contrast, QTc dispersion was not decreased by CRT in nonresponders (40 +/- 12 to 39 +/- 11 ms, not significant). The difference observed before CRT was thus abolished after CRT (52 +/- 15 vs 39 +/- 11 ms, not significant). Baseline values and changes in QRS width or QTc, as well as asynchrony of wall motion determined by tissue Doppler imaging, were not different between CRT responders and nonresponders before CRT. The present study with a small number of patients shows the potential utility of QTc dispersion for distinguishing CRT responders from CRT nonresponders before CRT, and warrants further study with a greater number of patients.

Global and Regional Ventricular Repolarization Study by Body Surface Potential Mapping in Patients with Left Bundle‐Branch Block and Heart Failure Undergoing Cardiac Resynchronization Therapy

“…Hina et al 23 showed that when we find the highest QTDc values before implantation of the resynchronization device (mean 102 ± 26 ms), patients are more likely to have a good response to CRT compared to nonresponders (mean 40 ± 12 ms), over a 3‐month follow‐up period. This type of analysis was not done in our study; however, we believe that this is a very elegant approach, considering that with simple data such as QTD values obtained by a reliable recording method, Hina et al were able to amass valuable information which can be used for prognosis and for further refining the indication for CRT.…”

Effect of cardiac resynchronization therapy on ventricular repolarization: A meta-analysis

“…1 and Table 1). In 3 of the 14 references, the data of endpoints were provided by subgroups (6, 14, 17). In 2 of the 14 references, the data was expressed as mean and standard error, the standard deviation was calculated (11, 15).…”

“…These findings were verified by another experimental study reported by Fish et al (23), which suggested that epicardial activation of left ventricular wall prolongs QT and TDR. However, results of following studies were inconsistent or even contradictory (7, 8, 14). Santangelo et al (7) reported that LV pacing enhanced QTD and TDR, whereas BV pacing significantly reduced QTD and TDR.…”

“…Anh et al (8) reported that compared with RA pacing, BV pacing produced shorter QT. Hina et al(14) reported that QTD and JT dispersion were significantly decreased after CRT in subgroup of CRT responders but no significant change in subgroup of CRT nonresponders. Another study of patients without structural heart disease suggested that RV pacing, LV pacing and BV pacing increased QT and Tp-e, but the effect of BV pacing was less than RV pacing and LV pacing (24).…”

Selection of Patient for Cardiac Resynchronization Therapy: Role of QT Corrected Dispersion

“…A small study performed on 26 patients with CHF who underwent CRT showed that QTc dispersion is potentially useful for distinguishing CRT responders from CRT nonresponders before CRT 34 …”