Ischemic ST-T Research Articles

The diagnostic value of QRS changes for prediction of coronary artery disease during exercise testing in women: false-positive rates.

The false positive rate of electrocardiographic exercise testing (ET) for coronary artery disease (CAD) in women ranges from 38 to 67%, using the ST-T changes (ST-T) criteria. The aim of this study was to compare the diagnostic accuracy of QRS duration change criteria with ST-T change criteria during ET. We studied 234 women (mean age 58+/-17 years, range 27-83 years), of whom 160 were pre-menopausal (PrMW; mean age 41+/-9, range 27-56) and 74 were post-menopausal (PoMW; mean age 65+/-7, range 57-83). All participants underwent ET to rule out CAD, followed by thallium stress testing (TL). QRS duration, measured with a computerized optical scanner and ST-T changes at peak ET were compared with TL. An ischemic QRS response was defined as an exercise-induced prolongation of QRS duration >3 ms. The sensitivities of QRS duration changes for the entire study group, the PrMW group and the PoMW group in comparison with TL, were 93, 88 and 92%, respectively, while the corresponding rates of specificity were 91, 85 and 91%, respectively. The sensitivities of ET ST-T changes for the entire study group, for the PrMW group and for the PoMW group were 48, 46 and 54%, respectively, while the corresponding rates of specificity were 62, 75 and 79%, respectively. The false-positive rate was 20% for ischemic ST-T and 4% for ischemic QRS duration for the entire study population. Computer-measured QRS duration changes during ET are more sensitive and specific than ST-T changes for the detection of ischemia in women.

High triglycerides/low high-density lipoprotein cholesterol, ischemic electrocardiogram changes, and risk of ischemic heart disease

Background High triglycerides (TG)/low high-density lipoprotein cholesterol (HDL-C)(TG ≥1.60 and HDL-C ≤1.18 mmol/L) and ischemic ST-T changes in the resting electrocardiogram (ECG) are both strong risk factors of ischemic heart disease (IHD) in men without clinical cardiovascular diseases. This study tested the hypothesis that men free of clinical IHD with high TG/low HDL-C and resting ischemic ECG changes would have a particularly poor prognosis with respect to IHD. Methods We conducted a cohort study of 2906 men, aged 53 to 74 years, without overt IHD at baseline. Results During 8 years, IHD developed in 229 men; 61 cases were fatal. Of the risk factors recorded, ischemic ECG changes and high TG/low HDL-C were the strongest risk factors of IHD. Compared with men without high TG/low HDL-C and without ischemic ECG changes, age-adjusted relative risk of total IHD (95% CI) was 3.5 (1.7-7.2) in men with both high TG/low HDL-C and ischemic ECG changes; the corresponding value for fatal IHD was 11.2 (4.9-25.8). Adjusted for conventional risk factors, the interaction term high TG/low HDL-C × ischemic ECG changes was a significant predictor of IHD death, with a relative risk of 2.6 (1.0-6.9). Conclusions In men free of clinical IHD, ischemic ECG changes were significantly more predictive of fatal IHD in men with high TG/low HDL-C, indicating an adverse synergistic effect of these 2 risk factors. (Am Heart J 2003;145:103-8.)

Occurrence of unrecognized myocardial infarction in subjects aged 45 to 65 years (the ARIC study)

Previous observational studies conducted predominantly in white men before 1988 estimated that 20% to 40% of myocardial infarctions (MIs) are unrecognized. Recent data on the proportion of MIs that are unrecognized, especially in women and African-Americans, are largely unavailable. Participants in the Atherosclerosis Risk in Communities (ARIC) study were men and women, aged 45 to 65 years, who were free of clinically recognized coronary heart disease and electrocardiographic evidence of MI at baseline (n = 12,843). Three follow-up clinic examinations were conducted approximately 3, 6, and 9 years after baseline, and included a 12-lead electrocardiogram at rest. Electrocardiographic evidence of infarction was defined as the appearance between the baseline and subsequent examinations of a major Q wave or a minor Q wave with ischemic ST-T changes. Clinically recognized (hospitalized) MI events were also identified and validated. Incident unrecognized MI was defined as electrocardiographic evidence of MI before, or in the absence of, a clinically recognized MI during the follow-up period. Of 508 MIs, 20% were unrecognized (95% confidence interval 16% to 23%), with African-Americans having a slightly higher percentage (23%) than whites (19%). The percentage of unrecognized MIs in men and women was similar. The percentage of unrecognized MIs in the ARIC sample between 1987 and 1998 was slightly lower than previous estimates from other populations.

QRS prolongation: a sensitive marker of ischemia during percutaneous transluminal coronary angioplasty.

The purpose of this study is to measure QRS duration changes in the human model of ischemia during percutaneous transluminal coronary angioplasty (PTCA) and compare these results to the commonly used ischemia markers, chest pain, and classical ST-T changes. Using a computerized method, QRS duration was measured in 51 patients undergoing elective PTCA. Three milliseconds (msec) or more prolongation of the QRS at peak inflation was considered to be an ischemic response. The results were compared to chest pain and ST-T changes and were analyzed for inflation site within individual coronary arteries. Forty-two patients had a pathological prolongation of the QRS during PTCA. Thirty-two patients developed chest pain, while 19 had ischemic ST-T changes. QRS duration was more prolonged in PTCA to proximal or middle segments of major arteries or their large branches, while it was less prolonged in distal segments or smaller branches. Using our method, QRS prolongation was an ischemia marker in most patients during PTCA and was more sensitive than chest pain or ST-T changes. QRS duration was more prolonged with occlusion of proximal and middle segments of major arteries. Cathet. Cardiovasc. Intervent. 50:177-183, 2000.

Comparison of electrocardiographic findings in patients with AL (primary) amyloidosis and in familial amyloid polyneuropathy and anginal pain and their relation to histopathologic findings

To assess the prevalence of chest pain and ischemic electrocardiographic (ECG) changes and relate them to histopathologic findings of coronary arteries in cardiac amyloidosis, 33 patients with AL (primary) amyloidosis and 60 patients with familial amyloid polyneuropathy (FAP) were examined. Five patients (15%) with AL amyloidosis had recurrent anginal pain with exertion and 2 of them also experienced anginal pain after orthostatic hypotension. The chest pain was associated with transient downsloping or horizontal ST-segment depression with or without T-wave inversion in right precordial leads, whereas the remaining patients with AL amyloidosis and all patients with FAP did not show anginal pain or ischemic ST-T changes. Histologic sections of coronary arteries were obtained in 12 patients with AL amyloidosis, including 4 of the 5 patients who had angina pectoris and in 25 patients with FAP. Three patients with anginal pain had variable degrees of stenoses of the intramural coronary arteries by amyloid deposition predominantly in the media with normal or nearly normal epicardial arteries. One patient with AL amyloidosis who had effort angina showed marked stenosis and complete occlusion of the small coronary vessels by transmural amyloid deposition. The remaining 8 patients with AL amyloidosis and 25 with FAP without chest pain did not exhibit any stenosis or occlusion of both the epicardial and intramural vessels. These findings suggest that ischemic ST-T changes with chest pain are not so rare in patients with AL amyloidosis, and that markedly decreased myocardial oxygen supply due to diffuse stenotic or occlusive disease of the small coronary vessels by amyloid deposition contributes to the development of clinically significant ischemic heart disease in these patients.

Analysis of the ST-T complex of the electrocardiogram using the Karhunen--Loève transform: adaptive monitoring and alternans detection.

The Karhunen-Loève transform (KLT) is applied to study the ventricular repolarisation period as reflected in the ST-T complex of the surface ECG. The KLT coefficients provide a sensitive means of quantitating ST-T shapes. A training set of ST-T complexes is used to derive a set of KLT basis vectors that permits representation of 90% of the signal energy using four KLT coefficients. As a truncated KLT expansion tends to favor representation of the signal over any additive noise, a time series of KLT coefficients obtained from successive ST-T complexes is better suited for representation of both medium-term variations (such as ischemic changes) and short-term variations (such as ST-T alternans) than discrete parameters such as the ST level or other local indices. For analysis of ischemic changes, an adaptive filter is described that can be used to estimate the KLT coefficient, yielding an increase in the signal-to-noise ratio of 10 dB (u = 0.1), with a convergence time of about three beats. A beat spectrum of the unfiltered KLT coefficient series is used for detection of ST-T alterans. These methods are illustrated with examples from the European ST-T Database. About 20% of records revealed quasi-periodic salvos of ischemic ST-T change episodes and another 20% exhibit repetitive, but not clearly periodic patterns of ST-T change episodes. About 5% of ischemic episodes were associated with ST-T alterans.

Hypertensive blood pressure response to exercise and ischemic ST-T segment changes: Correlation with myocardial perfusion scintigraphy

Hypertensive blood pressure response to exercise and ischemic ST-T segment changes: Correlation with myocardial perfusion scintigraphy

CETPと動脈硬化

Heterozygous CETP deficiency is found in ∼10% of the general Japanese population, and is an important genetic factor of increased HDL levels. A crosssectional epidemiologic survey in Kochi prefecture showed that subjects with very high HDL cholesterol levels≥80mg/dl exhibit a low CHD prevalence, irrespective of the CETP genotype. The cholesterol esterification rate was decreased in both homo- and heterozygous CETP deficiency. Increased levels of HDL itself, along with low non-HDL cholesterol levels, manifest anti-atherogenicity in subjects with very high HDL levels and CETP deficiency, possibly through direct effects of HDL on the arterial wall or an antioxidative mechanism. However, normolipidemic elderly men with low-to-intermediate HDL-C levels (<60mg/dl) and a D442G mutation, demonstrated ischemic ST-T change 3times more frequently. Thus, antiatherogenicity of CETP deficiency is dependent on serum HDL-C levels, and CETP genotyping/serum CETP measurement may be useful to identify a high-risk grop in subjects with serum HDL-C<60mg/dl.

Cardiological and general health status in preschool- and school-age children after neonatal arterial switch operation.

Cardiological and general health status 3-9 years after neonatal arterial switch operation for transposition of the great arteries should be evaluated by non-invasive methods. A total of 77 unselected children with intact ventricular septum (75.3%) or ventricular septal defect (24.7%) without or with aortic isthmic stenosis (5.2%) were prospectively examined 3.2-9.4 years (5.4 +/- 1.6) after neonatal switch. Clinical pediatric and cardiological examination, standard and 24 h Holter electrocardiogram, M-mode, 2D-, Doppler and colour Doppler echocardiography were performed. Outcome data were compared to published normals. Reoperation rate was 2.6%, 96.1% were without limitation of physical activity and 98.7% without medication. Compared to normals, growth was adequate, weight and head circumference were slightly reduced. After median sternotomy, 23.4% had abnormal thoracic configuration (16.9% asymmetry, 6.5% funnel chest). ECG and Holter: 93.5% were in sinus, 6.5% in ectopic atrial or junctional rhythm. Incidence of complete right bundle branch block was 15.8% in patients with ventricular septal defect and 5.2% in those without. Ischemic ST-T changes during exercise due to coronary artery occlusion and evidence of old myocardial infarction were found in 1 patient (1.3%) each. Occasional atrial ectopy was found in 27.4%, ventricular ectopy in 15.3%: occasional in 12.5% and frequent (> 30/h) in 2.8% presenting bigemini, couplets and short runs of ventricular tachycardia at rest and during exercise. Echocardiography: Left ventricular function was normal in all. Endsystolic diameter of neoaortic valve annulus was beyond 90% confidence interval for controls in 79.2%, neoaortic root diameter in 100%. Mild aortic insufficiency was seen in 10.4%. No correlation was found between aortic insufficiency and aortic dilatation. Neoaortic stenosis was not seen, mild residual coarctation after end-to-end-anastomosis was found in 2.6%, native coarctation corrected later on in 1.3%. Supravalvular pulmonary stenosis was seen in 29.9% (19.5% trivial, 7.8% mild, 2.6% moderate), mild subvalvular pulmonary stenosis in 1.3%, pulmonary insufficiency in 2.6%. The study confirms good midterm results after neonatal arterial switch operation for transposition with or without ventricular septal defect. Long-term observation is necessary to assess rhythm, coronary artery and myocardial function as well as development of neo-aorta and pulmonary artery system.

Impaired Left Ventricular Diastolic Filling Occurs in Diabetic Patients Without Atherosclerotic Coronary Artery Disease

Using left ventriculography, left ventricular diastolic function was studied in 24 diabetic patients who had angina pectoris without atherosclerotic large-vessel coronary artery diseases (group A, 14 patients with exercise-induced ischemic ST-T changes as seen during electrocardiogram; group B, 10 patients without such changes). In groups A and B, the global peak filling rate was significantly less than that in control patients without diabetes or cardiac diseases. The ratio of the global time to the peak filling rate to the diastolic time was higher in both groups A and B than in the control groups. However, the total of time differences, defined as the sum of the time differences between global time to the peak filling rate and each of the three regional time to the peak filling rate, was greater in group A than in either group B or the control patients. Total time difference was similar in group B and the controls. Left ventricular diastolic filling was impaired in diabetic patients without large-vessel coronary artery disease. Impaired diastolic filling was present regionally in patients with ischemic ST-T change but globally in those without such change.

Impaired Left Ventricular Diastolic Filling Occurs in Diabetic Patients Without Atherosclerotic Coronary Artery Disease

AbstractUsing left ventriculography, left ventricular diastolic function was studied in 24 diabetic patients who had angina pectoris without atherosclerotic large-vessel coronary artery diseases (group A, 14 patients with exercise- induced ischemic ST-T changes as seen during electrocardiogram; group B, 10 patients without such changes). In groups A and B, the global peak filling rate was significantly less than that in control patients without diabetes or cardiac diseases. The ratio of the global time to the peak filling rate to the diastolic time was higher in both groups A and B than in the control groups. However, the total of time differences, defined as the sum of the time differences between global time to the peak filling rate and each of the three regional time to the peak filling rate, was greater in group A than in either group B or the control patients. Total time difference was similar in group B and the controls. Left ventricular diastolic filling was impaired in diabetic patients without large-vessel coronary artery disease. Impaired diastolic filling was present regionally in patients with ischemic ST-T change but globally in those without such change.

Implication of the negative U wave during dobutamine stress echocardiography

Although the development of negative U waves during exercise is a highly specific marker for detecting coronary artery disease, their assessment during exercise is difficult. The clinical significance of the negative U wave during dobutamine stress echocardiography was investigated in 181 patients who had suspected coronary artery disease. Dobutamine-induced negative U waves appeared in 28 patients (16%) during dobutamine infusion. Coronary angiography showed coronary artery disease in 114 of the 181 patients. The sensitivity and specificity of the negative U wave for detecting coronary artery disease were 22 and 96%, respectively, while the corresponding values for ischemic ST-T changes were 49 and 76%, respectively. The negative U wave appeared during low-dose infusion of dobutamine (5–10 μg/kg/min) in 82% of the patients with this wave. In the 21 patients who had both a negative U wave and an inducible regional wall motion abnormality during dobutamine infusion, the development of the negative U wave was either simultaneous with or earlier than that of the wall motion abnormality. Although its sensitivity was low, the negative U wave during dobutamine stress echocardiography is a highly specific marker for detecting coronary artery disease. Because of its earlier appearance as compared with that of the wall motion abnormality, the dobutamine-induced negative U wave may be considered to be an early and useful adjunctive sign for detecting coronary artery disease during dobutamine stress echocardiography

Karhunen-Loève transform as a tool to analyze the ST-segment: Comparison with QT interval

The spatial and temporal courses of ventricular repolarization are quite sensitive to the biochemical and biophysiologic environment of the myocardial cells, and are therefore often an early marker of heart disease, particularly of ischemia. The detailed morphology of the surface electrocardiogram contains considerable information about the repolarization process. The ST-segment changes with ischemia, injury, and drugs. The QT interval is affected by drugs, heart rate, and autonomic tone, and in some situations may identify individuals at high risk for arrhythmias and sudden death. Variability in the shape, including duration, of the ST-T waves reflects autonomic nervous system activity and may identify high-risk patients. Automated methods for quantitatively characterizing ST-T complexes are important in studying long-term electrocardiographic records. Two computer-based measurement procedures for characterizing the repolarization period were comparatively analyzed: Karhunen-Loève (KL) transform representation of the ST-T shape and measurement of beat-to-beat durations of repolarization (QT intervals). The results of KL transform representation and time-domain QT measurement algorithms for studying the repolarization period of the electrocardiogram on the European ST-T database are presented. It was found that about 20% of the records present a quasiperiodic KL pattern of ischemic ST-T activity and another 20% exhibit repetitive but not clearly periodic patterns of ischemic ST-T changes. From these ischemic records, 50% showed QT variations in at least one lead associated with the ischemic episodes.

Heart rate variability before the occurrence of silent myocardial ischemia during ambulatory monitoring

Thirty-three ischemic episodes in 19 patients with stable coronary artery disease were studied to clarify changing autonomic nervous system activity during daily life before the occurrence of myocardial ischemia. Nonischemic points were studied for comparison of control data with ischemic episodes. These were defined as (1) patient showing no ischemic ST-T change while having the same heart rate with onset of ischemic episodes, and (2) presence within 1 to 2 hours before or after onset of ischernic episodes in the same patient. We analyzed heart rate (HR) variability during the 30-minute period before the onset and after the end of ischemic episodes during 24-hour monitoring. The period of 30 to 40 minutes before ischemia was regarded as the baseline, and HR variability was analyzed at 10-minute intervals before each ischemic episode and nonischemic point. HR variability was quantified on the band of 2 components: low frequency (0.04 to 0.15 Hz; LF) and high frequency (0.15 to 0.40 Hz; HF). Of the 33 episodes, 24 (73%) had a greater LF/HF value during the 30-minute period before ischemia than that before the nonischemic points. Distribution of the number of the 24 episodes demonstrated circadian rhythm with a peak from 8 to 10 A.M. HF power began to decrease from the last 10 minutes before ischemia, compared with baseline. A significant decrease in HF power with a background of greater value of LF/HF may explain the reduced ischemic threshold for ischemia during daily life.

Shift from left to right axis deviation during ischemia

A case report of a patient with persistent left anterior hemiblock admitted with acute ischemic heart disease is described. At effort during follow-up evaluation, the patient complained of retrosternal pain when the heart rate was 124 beats/min. No pathological ST-T changes were demonstrated at this time. At 133 beats/min, the precordial pain increased, the QRS axis displayed a marked shift to the right, and ischemic ST-T depression was recorded. In discussing this unreported phenomenon, it is pointed out that left anterior hemiblock does not necessarily represent an anatomical block of the atrioventricular bundle but may simply reflect a relative delay in conduction. In addition, acute ischemia may change the physiological behavior of the system resulting in slower conduction through the posterior rather than through the anterior atrioventricular bundle. The influence of left anterior and left posterior hemiblock on ischemic ST-T changes and on the coronary flow distribution is discussed.

Silent myocardial ischemia after acute myocardial infarction

Silent ischemia after myocardial infarction has definite prognostic significance but should be interpreted within the context of other prognostic indicators. The rationale for therapeutic intervention is based on the prognostic implications of silent ischemia and the potentially deleterious effect of repeated episodes of ischemia on the integrity of the left ventricle. We measured parameters of ischemia in 20 patients who showed asymptomatic ischemic ST-T changes on exercise testing in the early phase after myocardiol infarction. After diltiazem administration, a reduction of exercise induced ST-T depression from 2.3 ± 0.8 to 0.7 ± 0.6 mm (p < 0.01) occurred, and regional wall-motion score at exercise, determined by radionuclide anglography, improved significantly (p < 0.02). These and other observations warrant further studies in which the duration, severity and frequency of the ischemic episodes should be quantified and correlated with prognosis after myocardial infarction.

Temporal increase in resting coronary blood flow causes an impairment of coronary flow reserve after coronary angioplasty

Impaired coronary flow reserve immediately after coronary angioplasty may be attributed to an increase in resting coronary blood flow. To test this hypothesis we measured great cardiac venous flow (GCVF) at rest and during rapid atrial pacing before and immediately after angioplasty in 22 patients with significant narrowing of the left anterior descending artery and 12 patients (control group) with minimal narrowing. A follow-up (6 months) study was also done in seven patients. Immediately after angioplasty the coronary flow reserve (peak GCVF during pacing/resting GCVF) was not fully restored (1.5 ± 0.36 before angioplasty, 1.76 ± 0.42 after angioplasty, and 2.13 ± 0.33 in the control group). Resting coronary vascular resistance (2.4 ± 0.9 mm Hg/ml/min) was significantly decreased after angioplasty (2.0 ± 0.8 mm Hg/ml/min), whereas coronary vascular resistance during rapid pacing was fully restored to normal. Resting hyperemia was restored 6 months later, whereas coronary vascular resistance during pacing was unaltered. In five patients, however, slight ischemic ST-T changes were observed during rapid pacing, even after successful angioplasty associated with a decrease in the lactate extraction ratio. These results indicate that the impaired coronary flow reserve immediately after angioplasty may be attributed mainly to the temporal but significant increase in resting coronary flow, although impaired coronary vascular response to augmented myocardial oxygen demand may also be partially involved.

Prospective study on prevalence of esophageal chest pain in patients referred on an elective basis to a cardiac unit for suspected myocardial ischemia

The prevalence of esophageal chest pain was studied prospectively in patients referred on an elective basis to a cardiac unit for suspected myocardial ischemia. A group of 248 consecutive patients without previously documented heart disease was admitted for elective diagnostic coronary angiography. The clinical history classified 185 patients as having anginal pain and the coronary angiogram was normal in 48 of them. In 37 of these 48 patients full esophageal testing was performed including 24-hr intraesophageal pH and pressure recordings with indication of chest pain episodes as well as a number of esophageal provocation tests, ie, acid perfusion, edrophonium stimulation, balloon distension, and ergonovine stimulation, all performed under continuous esophageal manometric and electrocardiographic monitoring. In 19 of these 37 patients, the familiar chest pain could be reproduced by esophageal provocative testing without ischemic ST-T segment alterations; six of these 19 patients had also a positive 24-hr pH and pressure recording. These data strongly suggest an esophageal origin of chest pain in half the patients with typical angina and a normal coronary angiogram.

Anatomic basis for the injury current producing ST-segment shifts on the body surface ECG.

ST-segment depression is the characteristic electrocardiographic response to myocardial ischemia. A hypothesis is presented defining the structural and functional requirements for ischemic blood flow and ST-T wave potential gradients for ST-segment depression to occur. Both flow and potential gradients may be either transmural or transventricular. ST-segment depression results only when both are concordant (e.g., both transmural); however, ischemic ST-segment depression does not follow when flow and potential gradients are discordant (e.g., one transmural and one transventricular).

NOVACODE serial ECG classification system for clinical trials and epidemiologic studies.

Traditional serial electrocardiogram (ECG) change classification schemes used in clinical trials such as the Minnesota Code rely on independent classification of the baseline and each follow-up or acute event ECG, whereby graded changes in the hierarchic severity level of the code signify new events such as myocardial infarction (MI). This approach suffers from classification errors caused by repeated instability at decision boundaries at each step when the baseline and each acute event ECG is classified, and various "verification rules" must be used at the end of the coding process to prevent trivial serial changes from causing large transitions in coded events. The NOVACODE algorithms for visual and computer coding of serial ECGs were designed to alleviate some of these instability problems by quantifying changes in critical waveform patterns on a continuous scale. This is achieved by determining, for each ECG coded, a Q-QS Score, ST Depression Score, ST Elevation Score and T-Wave Score, each ranging from 0 to 50. In the next step, a score is derived for ST-T evolution and this ST-T Evolution Score together with changes in Q-QS Score define criteria for a hierarchic mutually exclusive serial ECG change classification scheme that includes coding categories for Q-wave and non-Q wave MIs, equivocal Q wave evolution, evolving ischemic ST-T abnormalities, and various combinations of nonevolving Q-QS wave, and ST-T abnormalities.(ABSTRACT TRUNCATED AT 250 WORDS)