Evaluation of depolarization changes during acute myocardial ischemia by analysis of QRS slopes

Objective

This study evaluates depolarization changes in acute myocardial ischemia by analysis of QRS slopes.

Methods

In 38 patients undergoing elective percutaneous coronary intervention, changes in upward slope between Q and R waves and downward slope between R and S waves (DS) were analyzed. In leads V1 to V3, upward slope of the S wave was additionally analyzed. Ischemia was quantified by myocardial scintigraphy. Also, conventional QRS and ST measures were determined.

Results

QRS slope changes correlated significantly with ischemia (for DS: r = 0.71, P < .0001 for extent, and r = 0.73, P < .0001 for severity). Best corresponding correlation for conventional electrocardiogram parameters was the sum of R-wave amplitude change (r = 0.63, P < .0001; r = 0.60, P < .0001) and the sum of ST-segment elevation (r = 0.67, P < .0001; r = 0.73, P < .0001). Prediction of extent and severity of ischemia increased by 12.2% and 7.1% by adding DS to ST.

Conclusions

The downward slope between R and S waves correlates with ischemia and could have potential value in risk stratification in acute ischemia in addition to ST-T analysis.     

Are exercise stress tests appropriate for assessing myocardial ischemia in patients with major depressive disorder?

Background

Major depressive disorder (MDD) disproportionately affects patients with coronary artery disease (CAD). Evidence of myocardial ischemia with electrocardiography (ECG) or single-photon-emission-computed-tomography (SPECT) assessments during exercise testing is an important determinant of CAD prognosis. However, many key symptoms of MDD, such as reduced interest in daily activities, lack of energy, and fatigue, may affect exercise performance and the detection of ischemia in patients with MDD. This study evaluated the extent to which MDD and depressive symptomatology moderate exercise test performance and compared the ability of ECG versus SPECT for detecting ischemia in 1367 consecutive patients who underwent exercise testing.

Methods

All patients underwent a brief, structured psychiatric interview (PRIME-MD) and completed the Beck Depression Inventory (BDI) on the day of their exercise (treadmill) test.

Results

A total of 183 patients (13%) met diagnostic criteria for MDD. Patients with MDD achieved a significantly lower percent of maximal predicted heart rate (%MPHR), exhibited lower peak exercise mets, and spent less time exercising compared with patients without MDD (all P values <.05). BDI scores were also negatively correlated with all 3 indices of exercise performance (all P values <.01). There were no differences in rates of SPECT ischemia in patients with MDD (40%) versus patients without MDD (45%; P = .23); however, rates of ECG ischemia were significantly lower (30%) in patients with MDD than in patients without MDD (48%; P <.0001).

Conclusions

Results suggest that patients with CAD who have MDD, depressive symptomatology, or both exhibit poor exercise tolerance and performance and that ECG, as compared with SPECT, may not be as reliable in detecting ischemia in patients who are depressed.     

Exercise-induced QT/R-R-interval hysteresis as a predictor of myocardial ischemia

Objectives

Exercise-induced QT/RR hysteresis exists when, for a given R-R interval, the QT interval duration is shorter during recovery after exercise than during exercise. We sought to assess the association between QT/RR hysteresis and imaging evidence of myocardial ischemia.

Background

Because ischemia induces cellular disturbances known to decrease membrane action potential duration, we hypothesized a correlation between QT/RR and myocardial ischemia.

Methods

We digitally analyzed 4-second samples of QT duration and R-R-interval duration in 260 patients referred for treadmill exercise stress and rest single photon emission computed tomography myocardial perfusion imaging; a cool-down period was used after exercise. None of the patients were in atrial fibrillation or used digoxin, and none had marked baseline electrocardiographic abnormalities. Stress and rest myocardial perfusion images were analyzed visually and quantitatively to define the extent and severity of stress-induced ischemia. QT/RR hysteresis was calculated using a computerized algorithm.

Results

There were 82 patients (32%) who manifested myocardial ischemia by single photon emission computed tomography myocardial perfusion imaging. The likelihood of ischemia increased with increasing QT/RR hysteresis, with prevalence according to quartiles of 20%, 30%, 26%, and 49% (P = .003 for trend). In analyses adjusting for ST-segment changes, exercise capacity, heart rate recovery, and other confounders, QT/RR hysteresis was independently predictive of presence of myocardial ischemia (adjusted odds ratio for 100-point increase of QT/RR hysteresis, 1.61; 95% confidence interval, 1.22-2.12; P = .0008). QT/RR hysteresis was also predictive of severe ischemia.

Conclusion

Exercise-induced QT/RR hysteresis is a strong and independent predictor of myocardial ischemia and provides additional information beyond that afforded by standard ST-segment measures.     

Improved myocardial performance during repetitive exercise testing: the role of extracellular superoxide dismutase activity in a model of exercise-induced myocardial preconditioning

Background

The aim of this study was to investigate whether endogenous antioxidant defense is involved in adaptation to myocardial ischemia in patients with coronary artery disease and severe exercise-induced myocardial ischemia.

Methods

Fifty patients, aged 50 to 72 years (mean, 58 ± 6 years), with positive exercise test results underwent 4 treadmill exercise tests. Thallium-201 scintigraphy was performed during the first and the fourth testing. The second, the third, and the fourth tests were performed the next day. The time interval between the second and the third test was 15 minutes, and between the third and the fourth test, the interval was 45 minutes. Extracellular superoxide dismutase activity was measured just before and at the peak of the first and the fourth exercise test.

Results

The patients were divided in 2 groups according to the extent of myocardial ischemia at peak exercise of the fourth test compared with the first test. Most of the patients studied (37/50) showed improved myocardial performance during the last of the sequential exercise tests, as demonstrated with the studied exercise parameters and the extent of myocardial ischemia in thallium-scintigraphy. Extracellular superoxide dismutase activity before the last exercise test was found to be significantly increased only in the patients who had improved myocardial performance at the last of the sequential exercise tests.

Conclusion

The beneficial effects of sequential episodes of exercise-induced myocardial ischemia seem to be strongly related to extracellular superoxide dismutase activity. Although there is still lack of direct evidence, our data support the theory that the favorable adaptation to repetitive exercise may represent an aspect of the clinical relevance of ischemic preconditioning in humans.     

Use of N-terminal pro-B-type natriuretic peptide to detect myocardial ischemia

Purpose

To evaluate the utility of plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels to detect myocardial ischemia.

Methods

We conducted a prospective observational study in 260 consecutive patients with suspected myocardial ischemia referred for rest/ergometry myocardial perfusion single-photon emission computed tomography. Levels of NT-proBNP were determined before and immediately after symptom-limited bicycle ergometry.

Results

Inducible myocardial ischemia on perfusion images was detected in 129 patients (49.6%). Baseline NT-proBNP and exercise induced increase in NT-proBNP (ΔNT-proBNP) were significantly higher in patients with myocardial ischemia (median baseline NT-proBNP 155 pg/mL vs 91 pg/mL, P <.001; ΔNT-proBNP 15 pg/mL vs 7 pg/mL, P = .002). Compared with patients in the lowest ΔNT-proBNP quartile, those in the highest quartile of ΔNT-proBNP had three times the risk of inducible ischemia (relative risk, 2.9; 95% confidence interval, 1.4 to 6.0; P = .003). Overall, the accuracy of baseline NT-proBNP and ΔNT-proBNP in the detection of myocardial ischemia were similar to that of the exercise electrocardiogram (ECG). Combining exercise ECG and baseline NT-proBNP or ΔNT-proBNP slightly increased the accuracy of exercise ECG only.

Conclusion

The NT-proBNP level at rest as well as ΔNT-proBNP during exercise stress testing is associated with inducible myocardial ischemia. NT-proBNP levels may have incremental value in the diagnosis of myocardial ischemia.     

The anti-ischemic effect of trimetazidine in patients with postprandial myocardial ischemia is unrelated to meal composition

Background

Previous studies provide evidence for a significant reduction of coronary flow reserve after ingestion of meals of different compositions. A possible role of hyperinsulinemia and increased free fatty acid levels, which are deleterious during acute myocardial ischemia and reperfusion, has been hypothesized. We assessed in patients with stable coronary disease the effects of high-fat meals (HFMs) and high-carbohydrate meals (HCMs) on ischemic threshold and stress left ventricular function on placebo and after partial fatty acid inhibition by trimetazidine (TMZ).

Methods

Ten patients (9 men, age 68 ± 7 years) were allocated to placebo and TMZ (40 mg TID), both administered in the 24 hours preceding testing, according to a randomized double-blind study design. All patients underwent stress (treadmill exercise testing according to the Bruce protocol) echocardiography after fasting (8 hours) and after an HFM and HCM (2 hours) either on placebo or on TMZ. Time to 1-mm ST-segment depression (time to 1 mm) and stress wall motion score index (WMSI) were evaluated.

Results

An HFM did not affect exercise variables compared with fasting, whereas an HCM resulted in a reduction of the ischemic threshold (time to 1 mm from 402 ± 141 to 292 ± 123 seconds, P = .025). Compared with placebo, TMZ improved time to 1 mm after fasting, HFM, and HCM (432 ± 153 vs 402 ± 141, 439 ± 118 vs 380 ± 107, 377 ± 123 vs 292 ± 123, F_1,9 = 26.91, P = .0006). Compared with placebo, on TMZ, stress WMSI decreased from 1.55 ± 0.25 to 1.29 ± 0.14 after fasting, from 1.57 ± 0.10 to 1.39 ± 0.28 after HFM, and from 1.64 ± 0.21 to 1.39 ± 0.21 after HCM (F_1,9 = 37.04, P = .0002). Interestingly, stress WMSI on TMZ was never different from rest WMSI on placebo.

Conclusions

In patients with coronary disease, exercise testing after an HCM results in more severe myocardial ischemia compared with that after an HFM. The observed beneficial effects of the partial fatty acid inhibitor TMZ seem to be unrelated to meal composition and are possibly caused by the better glucose use induced by the drug.     

Electrocardiographic poor R-wave progression: analysis of multiple criteria reveals little usefulness

Background

Poor or reverse R-wave progression (PRWP) is a common statement on electrocardiogram (ECG) interpretations, but its value in diagnosing anterior myocardial infarction (MI) is disputed. We assessed the accuracy of PRWP criteria in diagnosing anterior MI.

Methods

We searched MEDLINE (1960-1998) and found 3 criteria for PRWP. We included a modified version of the Marquette Muse system's criteria and multiple novel criteria. We interpreted resting ECGs of consecutive patients undergoing pharmacologic stress tests with dual isotope gated single photon emission computed tomography. Subjects with Q-wave anterior MI, bundle branch block, or Wolf-Parkinson-White syndrome were excluded. We established whether patients met the PRWP criteria. A nuclear cardiologist blinded to PRWP classifications reviewed the scintigrams. χ² Methods were used for statistical analysis.

Results

Inclusion criteria were met by 122 subjects. The standard PRWP criteria were met in 15% to 42% of ECGs. Of subjects meeting PRWP criteria, 2% to 9% had anterior MI and 27% to 33% had anterior MI or ischemia. These proportions were similar to those expected by chance. The performance of PRWP criteria did not improve when subjects with electrocardiographic left ventricular hypertrophy were excluded or when more stringent criteria for right precordial R-wave amplitude were tested.

Conclusions

In our study of patients undergoing cardiac stress tests, only a small percentage of patients who met various criteria for PRWP (a proportion no different than would be expected by chance) had anterior MI. Conclusions about the presence of anterior MI solely on the basis of PRWP have little usefulness.     

Chemical shift artifact on steady-state free precession cardiac magnetic resonance sequences as a result of lipomatous metaplasia: a novel finding in chronic myocardial infarctions

Background

Because balanced steady-state free precession (SSFP) sequences are opposed-phase gradient echo techniques, linear low signal due to chemical shift artefact is observed at fat-water interfaces. We observed that some patients with chronic myocardial infarctions had linear low signal along the inner myocardial wall in areas of infarction, which we postulated was due to chemical shift artefact, as a result of lipomatous metaplasia. The purpose of this retrospective review was to evaluate whether subendocardial low signal on SSFP, likely related to chemical shift artifact, could be used to identify chronic myocardial infarctions.

Methods

Of 128 patients who underwent cardiac magnetic resonance, 79 with myocardial infarctions were included in this retrospective study.

Results

Of the 79 patients, 35 (44%) demonstrated areas of linear subendocardial decreased signal. In 16 of those 35 (46%), the infarcts were confirmed as fatty by correlation with CT. In 29 of 35 (83%) of these patients, the infarcts were likely chronic based on fixed wall thinning to less than 4 mm. In 3 patients, chemical shift artifact due to lipomatous metaplasia was also confirmed with conventional in-phase and opposed-phase T1-weighted sequences. Subendocardial chemical shift artefacts were not seen in any of the 19 patients with known, acute infarcts included in this series. Aneurysms were more common when subendocardial chemical shift artefact was present (22 of 35), in comparison to patients who did not have this finding (10 of 44, P = 0.02).

Conclusions

Identification of linear subendocardial chemical shift artefacts on SSFP sequences is a sign of lipomatous metaplasia in chronic myocardial infarcts and is associated with an increased incidence of ventricular aneurysms.     

Chronotropic incompetence and its relation to exercise intolerance in hypertrophic cardiomyopathy

Background

Diminished functional capacity is common in hypertrophic cardiomyopathy (HCM), although the underlying mechanisms are complicated. We studied the prevalence of chronotropic incompetence and its relation to exercise intolerance in patients with HCM.

Methods

Cardiopulmonary exercise testing was performed in 68 patients with HCM (age 44.8 ± 14.6 years, 45 males). Chronotropic incompetence was defined by chronotropic index (heart rate reserve)/(220-age-resting heart rate) and exercise capacity was assessed by peak oxygen consumption (peak Vo₂).

Results

Chronotropic incompetence was present in 50% of the patients and was associated with higher NYHA class, history of atrial fibrillation, higher fibrosis burden on cardiac MRI, and treatment with β-blockers, amiodarone and warfarin. On univariate analysis, male gender, age, NYHA class, maximal wall thickness, left atrial diameter, peak early diastolic myocardial velocity of the lateral mitral annulus, history of atrial fibrillation, presence of left ventricular outflow tract obstruction (LVOTO) at rest, and treatment with beta-blockers were related to peak Vo₂. Peak heart rate during exercise, heart rate reserve, chronotropic index, and peak systolic blood pressure were also related to peak Vo₂. On multivariate analysis male gender, atrial fibrillation, presence of LVOTO and heart rate reserve were independent predictors of exercise capacity (R² = 76.7%). A cutoff of 62 bpm for the heart rate reserve showed a negative predictive value of 100% in predicting patients with a peak Vo₂ < 80%.

Conclusions

Blunted heart rate response to exercise is common in HCM and represents an important determinant of exercise capacity.     

Relation of admission QRS duration with development of angiographic no-reflow in patients with acute ST-segment elevation myocardial infarction treated with primary percutaneous interventions

Background

Although QRS-complex changes during ischemia have been described previously, their relation with no-reflow is not clear.

Purpose

To evaluate relation of admission QRS duration with angiographic no-reflow, we studied 162 patients who underwent primary angioplasty.

Methods

Twelve-lead electrocardiogram with a paper speed of 50 mm/s was recorded on admission and repeated after angioplasty. Patients were divided into reflow and no-reflow groups based on postangioplasty coronary thrombolysis in myocardial infarction flow grade.

Results

Patients in the no-reflow group (26 patients) were older (P = .001) and had significantly longer pain-to-balloon interval (P = .007). The patients in the no-reflow group had significantly longer QRS duration on admission electrocardiogram compared with patients in the reflow group (interquartile range, 80-93 [median, 84] milliseconds vs 60-80 [median, 76] milliseconds, respectively; P < .001). After adjusting all variables, QRS duration on admission was found to be independently related to angiographic no-reflow (odds ratio, 1.07; 95% confidence interval, 1.02-1.12; P = .003).

Conclusion

QRS duration on admission may be valuable in predicting no-reflow.     

Detection of hypertrophic cardiomyopathy is improved when using advanced rather than strictly conventional 12-lead electrocardiogram

Introduction

Twelve-lead electrocardiogram (ECG) is used to screen for hypertrophic cardiomyopathy (HCM), but up to 25% of HCM patients do not have distinctly abnormal ECGs, whereas up to 5% to 15% of healthy athletes do. We hypothesized that an approximately 5-minute resting advanced 12-lead ECG test (“A-ECG score”) could detect HCM with greater sensitivity than pooled conventional ECG criteria and distinguish healthy athletes from HCM with greater specificity.

Materials and methods

Five-minute 12-lead ECGs were obtained from 56 HCM patients, 56 age/sex-matched healthy controls, and 69 younger endurance-trained athletes. Electrocardiograms were analyzed using recently suggested pooled conventional ECG criteria and also A-ECG scoring techniques that considered results from multiple advanced and conventional ECG parameters.

Results

Compared with pooled criteria from the strictly conventional ECG, an A-ECG logistic score incorporating results from just 3 advanced ECG parameters (spatial QRS-T angle, unexplained portion of QT variability, and T-wave principal component analysis ratio) increased the sensitivity of ECG for identifying HCM from 89% (78%-96%) to 98% (89%-100%; P = .025), while increasing specificity from 90% (83%-94%) to 95% (92%-99%; P = .020).

Conclusions

Resting 12-lead A-ECG scores that are simultaneously more sensitive than pooled conventional ECG criteria for detecting HCM and more specific for distinguishing healthy athletes and other healthy controls from HCM can be constructed. Pending further prospective validation, such scores may lead to improved ECG-based screening for HCM.     

Systole-diastole mismatch in hypertrophic cardiomyopathy is caused by stress induced left ventricular outflow tract obstruction

Background

Pharmacological stress is used to assess the degree of left ventricular (LV) subvalvular gradient in patients with hypertrophic cardiomyopathy (HCM), but there is little information about associated physiological changes.

Methods

Echocardiography-Doppler ultrasound scanning measurements in 23 patients with HCM and 23 control subjects of similar age were studied at rest and at the end point of dobutamine stress.

Results

In patients, the systolic time was normal at rest, but increased abnormally with stress. In patients, the total isovolumic contraction time failed to shorten, and the total ejection time increased abnormally. Changes in total ejection time correlated with an increase in peak subvalvular gradient in control subjects and patients (r = 0.52 and r = 0.66, respectively; P <.01 for both). In patients, the diastolic time was normal at rest, but shortened abnormally with stress. In patients, the isovolumic relaxation time fell abnormally, as did the filling time. Mitral E wave acceleration and left atrium size were unchanged with stress in control subjects, but consistently increased in patients with HCM, which indicates an increased early diastolic atrioventricular pressure gradient.

Conclusion

In HCM, systolic period increases abnormally with stress. This is not because of a loss of inotropy, but is directly related to the degree of LV outflow tract obstruction. As a result, the diastolic period fails to increase, reducing the time available for coronary flow, the LV filling pattern is modified, and the diastolic atrioventricular pressure gradient increases. These changes may contribute to symptom development and suggest why reducing LV outflow tract obstruction per se may be therapeutically useful in HCM.     

The effects of sedative music, arousal music, and silence on electrocardiography signals

Introduction

Research indicates that music can affect heart rate, blood pressure, and skin conductance. Music can stimulate central emotions in the brain and release biochemical materials that change the physiologic state. We sought to compare changes in the electrical function of the heart in response to music.

Method

Subjects were asked to listen to 2 types of music, namely, sedative and arousal music, in conjunction with two 30-second periods of complete silence. The experiment was conducted in 4 segments: the first and third parts were silence, and the second and fourth parts were music. First, the response to each type of music was compared with that to the preceding period of silence. Next, the responses to both types of music were compared. Finally, the response to music regardless of the type was compared with that to silence.

Results

The amplitude of polarization and depolarization changed in response to different kinds of music. The electrical function of the heart in response to music, irrespective of the music type, differed from that in response to silence. The 2 types of music impacted the electrical function of the heart in different ways: the arousal music influenced T-wave maximum amplitude, whereas no such change was recorded in response to the sedative music.

Conclusions

The bandwidth of the polarization and depolarization of the heart rate and R-wave amplitude increased in response to music by comparison with silence. In addition, the heart did not seem to try to synchronize with music. The mean R-wave amplitude in sedative music is higher than the arousal music, so our heart works differently when different types of music are heard.     

Grade 3 ischemia on the admission electrocardiogram is associated with severe microvascular injury on cardiac magnetic resonance imaging after ST elevation myocardial infarction

Background

Grade 3 ischemia during ST elevation myocardial infarction (STEMI) is defined as ST elevation with distortion of the terminal portion of the QRS on electrocardiogram (ECG). The aim of this study was to evaluate the effect of ischemic grade on cardiac magnetic resonance (CMR) imaging infarct characteristics such as infarct size, microvascular obstruction (MVO), intramyocardial hemorrhage (IMH), and myocardial salvage.

Methods

Patients with STEMI treated with primary percutaneous coronary intervention had a 12-lead ECG on presentation for analysis of ischemic grade. Gadolinium-enhanced CMR imaging was performed within 7 days to assess infarct size, MVO, IMH, and myocardial salvage.

Results

Of the 37 patients enrolled in the study, grade 3 ischemia was present in 32%. Those with grade 3 ischemia had higher peak troponin I levels (P = .013), more MVO (P < .001), more IMH (P < .001), larger infarct size (P = .025), and less myocardial salvage (P = .012). Regression analysis found that grade 3 ischemia, infarct size, and peak troponin I level were significantly associated with MVO and IMH.

Conclusion

Grade 3 ischemia on the admission ECG during STEMI is closely associated with the development of severe microvascular damage on CMR imaging.     

Pacemaker stress echocardiography predicts cardiac events in patients with permanent pacemaker

Purpose

Noninvasive pacemaker stress echocardiography is a newly introduced method for the diagnosis of coronary artery disease in patients with a permanent pacemaker. The prognostic value of pacemaker stress echocardiography has not been studied.

Subjects and methods

We studied 136 patients (mean age 64 ± 12 years) with a permanent pacemaker who underwent pacemaker stress echocardiography for evaluation of coronary artery disease. All patients underwent pacemaker stress echocardiography by external programming (pacing heart rate up to ischemia or target heart rate).

Results

Thirty-one patients (23%) had normal study results. Ischemia was detected in 75 patients (55%). During a mean follow-up of 3.5 ± 2.4 years, 35 deaths (26%) (20 the result of cardiac causes) and 2 nonfatal myocardial infarctions (1%) occurred. The annual cardiac death rate was 1.3% in patients without ischemia and 4.6% in patients with ischemia (P = .01). The annual all-cause mortality rate was 3.1% in patients without ischemia and 7% in patients with ischemia (P = .004). The presence of ischemia during pacemaker stress echocardiography was the strongest independent predictor of cardiac death (hazard ratio 4.1, confidence interval 1.2-14.5) and all-cause mortality (hazard ratio 2.7, confidence interval 1.2-6.0) in a multivariable model.

Conclusion

Myocardial ischemia during pacemaker stress echocardiography is an independent predictor of cardiac death and all-cause mortality in patients with a permanent pacemaker.     

Ischemic ST-segment episodes during the initial 24 hours of ST elevation myocardial infarction predict prognosis at 1 and 5 years

Objectives

The aims of the study were to assess the prognostic value of recurrent ischemic episodes during the first 24 hours in ST elevation myocardial infarction (STEMI) treated with thrombolysis and to explore those episodes as a part of a low-risk prognostic feature.

Design

Two hundred twenty patients with STEMI treated with thrombolysis were monitored for 24 hours with continuous online vectorcardiography assessing ST vector changes to record recurrent ischemic events.

Results

Ischemic events measured as an increase in ST-change vector magnitude (STC-VM) more than 50 μV for at least 2 minutes during 4- to 24-hour predicted mortality in a 5-year follow-up based on a multivariable analysis (hazard ratio, 1.18/episode; confidence interval, 1.01-1.37). The more episodes there were, the worse the prognosis. A low-risk group with a 1-year mortality of 1.9% could be identified.

Conclusion

Continuous ST-segment monitoring during the first 24 hours of a myocardial infarction is a valuable tool for identifying high- and low-risk patients. The STC-VM events during 4 to 24 hours of the first day of a myocardial infarction predict mortality within 5 years.     

Validation of the accuracy of pretest and exercise test scores in women with a low prevalence of coronary disease: the NHLBI-sponsored Women's Ischemia Syndrome Evaluation (WISE) study

Background

Recently revised American College of Cardiology/American Heart Association guidelines have suggested that exercise test scores be used in decisions concerning patients with suspected coronary artery disease (CAD). Pretest and exercise test scores derived for use in women without known CAD have not been tested in women with a low prevalence of CAD.

Methods

Within the Women's Ischemia Syndrome Evaluation (WISE) study, we evaluated 563 women undergoing coronary angiography for suspected myocardial ischemia. The prevalence of angiographic CAD was 26%. Overall, 189 women underwent treadmill exercise testing. Prognostic end points included death, myocardial infarction, stroke, and revascularization.

Results

Each score stratified women into 3 probability groups (P <.001) according to the prevalence of coronary disease: Pretest: low 20/164 (12%), intermediate 53/245 (22%), high 75/154 (49%); Exercise test: low 11/83 (13%), intermediate 22/74 (30%), high 17/32 (53%). However, the Duke score did not stratify as well: low 7/46 (15%), intermediate 36/126 (29%), high 6/17 (35%); P = .44. When pretest and exercise scores were considered together, the best stratification with the exercise test score was in the intermediate pretest group (P < .03). The Duke score did not stratify this group at all (P = .98). Pretest and exercise test scores also stratified women according to prognostic end points: pretest—low 7/164 (4.3%), intermediate 28/245 (11.4%), high 27/154 (17.5%), P < .01; exercise test—low 4/83 (4.8%) and intermediate-high 17/106 (16%), P = .014.

Conclusion

Both pretest and exercise test scores performed better than the Duke score in stratifying women with a low prevalence of angiographic CAD. The exercise test score appears useful in women with an intermediate pretest score, consistent with American College of Cardiology/American Heart Association guidelines.     

Comparison of high-frequency QRS components and ST-segment elevation to detect and quantify acute myocardial ischemia

Objective

This study tests the ability of high-frequency components of the depolarization phase (HF-QRS) vs conventional ST-elevation criteria to detect and quantify myocardial ischemia.

Methods

Twenty-one patients admitted for elective percutaneous coronary intervention were included. Quantification of the ischemia was made by myocardial scintigraphy. High-resolution electrocardiogram before and during percutaneous coronary intervention was recorded and signal averaged. The HF-QRS were determined within the frequency band 150 to 250 Hz. ST-segment deviation was measured in the standard frequency range (<100 Hz).

Results

HF-QRS criteria were met by 76% of the patients, whereas 38% met the ST-elevation criteria (P = .008). Both HF-QRS reduction and ST elevation correlated significantly with the amount of ischemia (HF-QRS: r = 0.59, P = .005 for extent and r = 0.69, P = .001 for severity; ST elevation: r = 0.49, P = .023 for extent and r = 0.57, P = .007 for severity).

Conclusions

This study suggests that HF-QRS analysis could provide valuable information both to detect acute ischemia and to quantify myocardial area at risk.     

Novel methodology for the detection of exercise-induced myocardial wall motion abnormalities by surface electrocardiogram during exercise test

Background

We investigated whether ischemia-induced wall motion abnormalities during exercise test modify electrical vector variation.

Methods

We performed treadmill exercise test and thallium 201 scintigraphy in 150 normotensives. Beat-to-beat change of direction of S wave in V₁ (reference lead) was compared with that of R wave in V₅ and aVF, representative of anterior and inferior walls, respectively. The percentage of neighboring QRS couples where S wave in V₁ and R wave in V₅ or aVF change toward the same direction (increase or decrease) constitutes V1-V5 and V1-aVF indexes.

Results

V1-V5 and V1-aVF indexes were significantly decreased in subjects with reversible anterior or inferior ischemia, respectively. A decrease in V1-V5 index ≥0.14 defines those with anterior wall ischemia (sensitivity, 100%; specificity, 75.5%), whereas a decrease in V1-aVF index ≥0.05 defines those with inferior wall ischemia (sensitivity, 92.3%; specificity, 61.5%).

Conclusions

These novel electrocardiographic exercise test indexes improved significantly their sensitivities.     

Obstructive intramural coronary amyloidosis and myocardial ischemia are common in primary amyloidosis

Purpose

The purpose of this study was to determine the prevalence of clinical syndromes and pathologic changes of myocardial ischemia due to obstructive intramural coronary amyloidosis among patients with primary amyloidosis and cardiac involvement.

Subjects and methods

Medical records and pathologic specimens were reviewed from 96 patients with primary amyloidosis and cardiac involvement at autopsy or after cardiac transplantation during a 20-year period. Medical records were reviewed for patient demographic and clinical characteristics, including evidence for syndromes of myocardial ischemia. Pathologic specimens were examined for obstructive intramural coronary amyloidosis and microscopic changes of myocardial ischemia.

Results

Obstructive intramural coronary amyloidosis was present in 63 of 96 patients (66%). Microscopic changes of myocardial ischemia were more common in patients with obstructive intramural coronary amyloidosis (86%) than in those without (52%) (P <.001). In the 76 patients without coexistent severe epicardial coronary atherosclerosis, changes of myocardial ischemia were more common in those with obstructive intramural coronary amyloidosis (83%) than in those without (45%) (P <.001). In patients who had tissue available for review, none had obstruction of epicardial coronary arteries from amyloid. Syndromes of myocardial ischemia affected 16 patients (25%) with obstructive intramural coronary amyloidosis but only 2 patients (6%) without (P = .027). For 11% of the patients with obstructive intramural coronary amyloidosis, a syndrome of myocardial ischemia consisting of acute myocardial infarction or angina pectoris was the first manifestation of primary amyloidosis.

Conclusion

Most patients with primary systemic amyloidosis and cardiac involvement have obstructive intramural coronary amyloidosis and associated microscopic changes of myocardial ischemia. Syndromes of myocardial ischemia may occur in these patients.