RT-83
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Effect of coronary angioplasty and stent implantation on QT dispersion
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Maria Stella Fera, Andrea Mazza, Roberto Violini, Giovanni Pulignano, Edoardo Pucci, Ernesto Lioy, Francesca Bettiol, Ezio Giovannini.
Cardiology Department, S. Camillo Hospital, Rome, Italy
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Abstract
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QT interval dispersion (QTd) represents the
heterogeneity of the ventricular repolarization and may be a risk marker in the acute ischemic syndromes.
Aim of our study was to assess the QTd variations after percutaneous transluminal coronary
angioplasty (PTCA) + successful coronary stent implantation in patients (pts) with unstable
angina (UA) and recent myocardial infarction (MI).
METHOD. One hundred and four pts (mean age 66±12 yrs) with recent (<1 month)
MI – 44 pts (42%) – anterior 30 pts and inferior 14 pts + early angina (Gr. 1) or with UA –
60 pts (58%) – and coronary lumen narrowing >70% (Gr. 2) were enrolled in the study.
PTCA was performed in each critical coronary lesion with stent implantation whenever
possible. QTd was calculated as the difference between the maximum and minimum QT,
and QT corrected for HR (QTc) by using Bazett’s formula was utilized for calculating QTcd.
All measurements were obtained manually and blindly on a surface 12-lead ECG at a paper
speed of 50 mm/sec recorded immediately before and one day after the procedure.
RESULTS. One hundred and four pts with recent MI and early angina (Gr. 1) – 44 pts
(42%) (30 anterior and 14 inferior MI) and with UA (Gr. 2) – 60 pts (58%) were studied. All of
them had a coronary lumen stenosis >70% in one or two coronary vessels. Mean left ventricular
ejection fraction was 0.50±11. The procedure was successful in all cases (residual stenosis <30%
of the lumen diameter). One hundred and sixty-four critical stenosis were treated with PTCA, 76
in the left anterior descending coronary artery (LAD), 50 in the right coronary artery (RCA) and 38
in the left circumflex coronary artery (LCA). A stent was implanted in 74 stenoses in the LAD (98%),
in 35 in the RCA (70%) and in 23 stenoses in the LCA (60%). A total of 132 stents (80%) were
implanted out of 164 critical stenoses. No significant procedural complications occurred.
Both QT and QTc interval dispersion in all pts significantly decreased after PTCA+stent implantation
(46±12 vs 31±6 ms p<0.05 – 54±10 vs 43±7 ms p<0.05, respectively). Both QT and QTc interval
dispersion significantly decreased after PTCA+stent implantation either in Gr. 1 (48±7 vs 33±6 ms
p<0.05 – 53±5 vs 46±8 ms p<0.05, respectively), either in Gr. 2 (45±9 vs 30±7 ms p<0.001 –
55±7 vs 41±9 ms p<0.001).
CONCLUSIONS. Both QTd and QTcd values significantly decreased after a successful PTCA
+ stent implantation in pts affected by UA more than in post-MI pts; they may be considered as
a precocious non-invasive marker of myocardial revascularization.
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Key Words
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