ABSTRACT
A young woman presented with takotsubo cardiomyopathy after a syncopal attack caused by torsades de pointes. Two-dimensional echocardiography on admission showed left ventricular apical akinesis (ballooning) and basal hyperkinesis, compatible with takotsubo cardiomyopathy. This gradually normalized in 2 months. ECG on admission showed remarkable QT prolongation, U waves, and negative T waves, which also gradually normalized. Coronary angiography revealed no organic stenosis; however, acetylcholine provocation test caused the QT interval to again become prolonged. During treadmill exercise stress testing, the QT interval shortened as heart rate increased. Therefore, without genetic analysis, this patient was considered to have sporadic long QT syndrome in which takotsubo cardiomyopathy developed after the syncopal attack caused by torsades de pointes.
Subject(s)
Cardiomyopathies , Long QT Syndrome , Syncope , Torsades de Pointes , Adult , Cardiomyopathies/complications , Cardiomyopathies/diagnostic imaging , Cardiomyopathies/drug therapy , Female , Humans , Long QT Syndrome/complications , Long QT Syndrome/diagnostic imaging , Long QT Syndrome/drug therapy , Syncope/complications , Syncope/diagnostic imaging , Syncope/drug therapy , Torsades de Pointes/complications , Torsades de Pointes/diagnostic imaging , Torsades de Pointes/drug therapy , UltrasonographyABSTRACT
BACKGROUND: The utility of exercise echocardiography for evaluating remote ischemia due to noninfarct-related artery (n-IRA) lesions in patients with prior myocardial infarction has not been established. METHODS: Quantitative coronary angiography and treadmill exercise echocardiography were performed within 2 weeks in 115 patients with prior myocardial infarction (>6 weeks) and 224 patients without myocardial infarction. Coronary lumen diameter stenosis > or =50% (by angiography) and the lack of a hyperdynamic response on exercise echocardiography were considered significant. Myocardial infarction size was defined as the number of myocardial segments with severe hypokinesis, akinesis, or dyskinesis on echocardiography at rest. RESULTS: For detection of n-IRA lesions in patients with prior myocardial infarction, the sensitivity of exercise echocardiography was similar (78% vs 79%, P = not significant), however, the specificity was significantly lower (77% vs 91%, P <.01) than for detection of significant stenoses in patients without prior myocardial infarction. Angiographic percent-diameter stenosis, presence of collateral vessel, achieved exercise level, and presence of peri-infarct ischemia did not affect the specificity of exercise echocardiography. However, the specificity of exercise echocardiography was significantly lower (69% vs 84%, P <.05) in patients with echocardiographically large infarction (infarction size > or =2) than in patients with small infarction (infarction size <2). CONCLUSION: In patients with prior myocardial infarction, exercise echocardiography showed low specificity for detection of noninfarct-related artery lesions, especially in patients with echocardiographically large myocardial infarction. These characteristics of treadmill exercise echocardiography should be considered when this technique is applied for patients with healed myocardial infarction.
Subject(s)
Coronary Disease/diagnosis , Echocardiography , Exercise Test , Myocardial Infarction/complications , Aged , Coronary Angiography , Coronary Disease/complications , Female , Humans , Male , Middle Aged , Risk Factors , Sensitivity and SpecificityABSTRACT
This clinical study examines the diagnostic accuracy of exercise echocardiography for detecting significant coronary stenoses in infarct-related arteries in patients with healed myocardial infarction. Quantitative coronary angiography and exercise echocardiography using treadmill testing were performed within 2 weeks of each other in 123 patients with a prior myocardial infarction. Coronary lumen diameter stenosis > or =50% by quantitative coronary angiography and the lack of a hyperdynamic response on exercise echocardiography was considered significant. For detection of infarct-related coronary lesions, treadmill exercise echocardiography was highly sensitive (91%) but less specific (59%) than for detection of non-infarct-related artery lesions. The 2 groups of patients with large and small infarct sites had similar sensitivity for detection of residual stenosis of the infarct-related artery (88% vs 96%, p = NS); however, the specificity of the small infarct sites for this purpose was significantly higher than that of the large infarct sites (86% vs 33%, p < 0.01). When remote ischemia was detected on exercise echocardiography, the specificity of exercise echocardiography was significantly lower (33% vs 70%, p < 0.05) than when remote ischemia was not present. Thus, although there is high sensitivity, the specificity of treadmill exercise echocardiography for detecting infarct-related artery lesions is limited. However, high specificity is maintained when the infarct size is small and/or remote ischemia is not present.
