Background It has been suggested that corrected QT dispersion (cQTD) provides a measure of repolarisation inhomogeneity; however, the existence of a relationship between cQTD and cardiac outcomes is controversial.

Objective To assess whether changes in cQTD following percutaneous coronary intervention (PCI) predict long-term survival.

Design Prospective observational study.

Setting Single tertiary care centre.

Main outcome measures Cardiac mortality.

Patients 612 patients had a 12-lead ECG recorded before and 6 h after PCI, and were followed-up for 49±10 months.

Results PCI was associated with a significant overall reduction of cQTD at 6 h versus baseline (p<0.001); a reduction in cQTD occurred in 343 patients (56%). During the follow-up, 46 deaths (7.5%) were recorded, 21 of which for non-cardiac and 25 for cardiac causes. At Cox regression analysis, a reduced ΔcQTD (cQTD baseline − 6 h) was an independent predictor of cardiac mortality (HR=1.497; 95% CI 1.081 to 2.075 for each 20 ms decrease; p=0.015), together with age (HR=1.672; 95% CI 1.039 to 2.691 per 10 years increase; p=0.034), diabetes (HR=2.622; 95% CI 1.112 to 6.184; p=0.028), peak CK-MB (HR=1.798; 95% CI 1.063 to 3.039 per each unit increase over normal level; p=0.029), three-vessel coronary artery disease (HR=3.626; 95% CI 1.079 to 12.187; p=0.037) and the number of treated lesions (HR=2.066; 95% CI 1.208 to 3.532; p=0.008). Patients in the lowest tertile of ΔcQTD and having a post-procedural increase of CK-MB had a considerably higher cardiac mortality than the remaining population (14.6 vs 2.4%, p<0.001).

Conclusions cQTD decreases after PCI. A defective cQTD recovery, suggesting the persistence of repolarisation inhomogeneities, predicts long-term cardiac mortality.