Document Detail

Exercise-induced QTc-interval changes for predicting improvement in regional blood flow in ischemic myocardium and cardiac output after coronary angioplasty in patients with right bundle-branch block.
MedLine Citation:
PMID:  10803445     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: We have previously shown that QT-interval changes are more useful than ST-T changes in evaluating the severity of exercise-induced myocardial ischemia in patients with right bundle-branch block (RBBB). HYPOTHESIS: The purpose of this study was to evaluate whether the improvement in regional myocardial blood flow (RMBF) in ischemic areas and cardiac output after percutaneous transluminal coronary angioplasty (PTCA) can be predicted by exercise-induced QT-interval changes prior to PTCA. METHODS: The RMBF and cardiac output were quantified with nitrogen-13 ammonia positron emission tomography at rest and during exercise in 20 patients with RBBB and ischemic heart disease before and 6 months after PTCA, and in 9 healthy volunteers. RESULTS: Before PTCA, exercise-induced prolongation by < 20 ms or shortening of the Bazett-corrected QT (QTc) interval (454 +/- 38 to 451 +/- 41 ms, p = NS) was observed in 13 patients (Group 1) and prolongation by > or = 20 ms (429 +/- 44 to 466 +/- 50 ms, p < 0.002) was observed in 7 (Group 2). The number of regions of exercise-induced ischemia was significantly greater in Group 2 than in Group 1 (4.0 +/- 1.2 vs. 2.1 +/- 1.2, p < 0.01). The RMBF in regions of exercise-induced ischemia and cardiac output at rest was not significantly different between Groups 1 and 2, whereas during exercise both the parameters were significantly lower in Group 2 than in Group 1 (both p < 0.05). After successful PTCA, RMBF both at rest and during exercise improved significantly in Group 1 (0.67 +/- 0.04 to 0.71 +/- 0.06 ml/min/g, 0.74 +/- 0.05 to 0.84 +/- 0.08 ml/min/g; both p < 0.0001), but did not improve significantly in Group 2 (0.63 +/- 0.05 to 0.65 +/- 0.07 ml/min/g, 0.65 +/- 0.04 to 0.69 +/- 0.11 ml/ min/g; both p = NS). Cardiac output during exercise improved significantly in Group 1 (6.4 +/- 0.7 to 7.4 +/- 0.9 l/min; p < 0.002) but not in Group 2 (5.7 +/- 0.6 to 5.9 +/- 0.6 l/min; p = NS). CONCLUSIONS: Our results suggest that the marked prolongation of the QTc interval induced by pre-PTCA exercise may predict a lack of improvement in RMBF in ischemic areas and cardiac output after PTCA in patients with RBBB and ischemic heart disease.
T Watanabe; T Michihata; H Yamanaka; Y Akutsu; O Okazaki; T Katagiri; K Harumi
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Publication Detail:
Type:  Clinical Trial; Comparative Study; Controlled Clinical Trial; Journal Article    
Journal Detail:
Title:  Clinical cardiology     Volume:  23     ISSN:  0160-9289     ISO Abbreviation:  Clin Cardiol     Publication Date:  2000 May 
Date Detail:
Created Date:  2000-07-21     Completed Date:  2000-07-21     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7903272     Medline TA:  Clin Cardiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  359-64     Citation Subset:  IM    
Third Department of Internal Medicine, Showa University School of Medicine, Tokyo, Japan.
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MeSH Terms
Analysis of Variance
Angioplasty, Transluminal, Percutaneous Coronary*
Bundle-Branch Block / diagnosis*
Cardiac Output / physiology
Coronary Angiography
Coronary Circulation / physiology*
Exercise Test
Middle Aged
Myocardial Ischemia / diagnosis,  radionuclide imaging*,  therapy*
Predictive Value of Tests
Regional Blood Flow
Statistics, Nonparametric
Tomography, Emission-Computed

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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