Impact of infarct-related artery flow on QT dynamicity in patients undergoing direct percutaneous coronary intervention for acute myocardial infarction.
BACKGROUND
Complete coronary artery reperfusion in acute myocardial infarction (AMI) has been shown to significantly improve survival. Electrical stability may be the decisive mechanism for this beneficial effect. Because electrical stability is largely dependent on ventricular repolarization, we sought to determine the impact of a modern reperfusion strategy (ie, direct percutaneous coronary intervention [PCI]) on QT dynamicity in AMI and examined its association with infarct-related artery flow.


RESULTS
We prospectively investigated QT dynamicity in 128 patients undergoing direct PCI for a first AMI. Slopes and correlation coefficients of the linear QT/RR regression were determined in the time interval before reperfusion, within the initial hour after reperfusion, and within the remaining recording period from Holter ECG recordings, which were initiated on admission. Subgroup analysis based on TIMI 3 (n=100) and TIMI 2 (n=28) flow after PCI revealed no significant differences in QT/RR slope before PCI (0.145+/-0.12 versus 0.160+/-0.19,P=NS). After PCI, QT/RR slopes increased only in the TIMI 2 subgroup (P<0.05). In TIMI 2 patients, QT/RR slopes were significantly steeper in the hour after PCI and in the remaining recording period, respectively (0.155+/-0.12 versus 0.192+/-0.15,P<0.05, and 0.159+/-0.10 versus 0.210+/-0.17,P<0.01).


CONCLUSIONS
Alterations of QT dynamicity in patients with incomplete reperfusion may suggest an altered electrical restitution, potentially providing a substrate for serious ventricular arrhythmias. Thus, our findings offer new insights into mechanisms by which complete reperfusion may affect electrical stability.
Bonnemeier
Hendrik
H
Universität zu Lübeck, Medizinische Klinik II, Lübeck, Germany. Bonnemei@medinf.mu-luebeck.de
Wiegand
Uwe K H
UK
Bode
Frank
F
Hartmann
Franz
F
Kurowski
Volkhard
V
Katus
Hugo A
HA
Richardt
Gert
G
D015906:Angioplasty, Balloon, Coronary; D003326:Coronary Circulation; D004562:Electrocardiography; D005260:Female; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000628:therapy*