Spectral Analysis of the High Resolution QRS Complex During Exercise-Induced Ischemia

Background: The effect of acute myocardial infarction and regional ischemia on the frequency content of the ECG signal has been described by several investigators. In the present study, the feasibility of assessing changes in the QRS spectrum during exercise testing, and whether these changes are related to the occurrence of ischemia were examined. Methods: Spectral analysis of the high resolution ECGs from leads V₃, V₄, V₅, and V₆ were performed in two groups of male subjects before, during, and following treadmill exercise testing. Group A included 32 coronary artery disease (CAD) patients, with arteriographically proven >75% obstruction of at least two main coronary arteries, and group B included 30 healthy subjects, without history or symptoms of CAD. Signal averaging and filtering techniques were used in order to enhance the signal-to-noise ratio of the recorded ECGs. The power spectrum of the averaged QRS waveform for the different stages of the exercise testing was computed using a Fast Fourier Transform, and the slope of the linear regression line was found in the frequency range 7.81–249.92 Hz on the plot of log((amplitude)²) versus log(frequency). Results: Regression line slopes immediately after peak exercise were significantly lower for the CAD group than for the healthy subjects in 3 of the 4 examined leads. No significant changes in slopes were found between the two groups at rest or during late recovery. Comparing the differences between slopes at different stages of the test revealed that the difference between postexercise slope and rest slope has lower mean values for the CAD group in all four leads, with a significant difference in lead V6, and for the difference between postexercise slope and recovery slope, lower mean values were found for the CAD group in all four leads, with a significant difference in V5 and V6. Conclusions: These findings indicate that ischemic changes affect the power spectrum of the QRS complex, and result in a steeper regression line on a log-log scale.     

Maximal increase in sensitivity with minimal loss of specificity for diagnosis of acute coronary occlusion achieved by sequentially adding leads from the 24-lead electrocardiogram to the orderly sequenced 12-lead electrocardiogram

Objectives

This study investigates whether sequential addition of inverted (negative) leads from the 24-lead electrocardiogram (ECG) to the orderly sequenced 12-lead ECG would identify a number of leads with which the sensitivity for diagnosis of acute transmural ischemia is significantly increased with minimal loss of specificity.

Background

Acute transmural ischemia due to thrombotic coronary occlusion typically progresses to infarction. Its recognition is based on currently accepted ST-elevation myocardial infarction (STEMI) criteria with suboptimal sensitivity, which could be potentially increased by consideration of the principle that each of the 12 ECG leads can be inverted to provide an additional lead with the opposite (180°) orientation, generating a 24-lead ECG.

Methods

The study population included 162 patients who underwent prolonged coronary occlusion during elective percutaneous transluminal coronary angioplasty. Balloon occlusion was performed in the left anterior descending coronary artery (51 patients), in the right coronary artery (67 patients), or in the left circumflex coronary artery (44 patients). To be classified as indicative of the epicardial injury current of acute ischemia, the ECGs had to fulfill either the criteria of a consensus document from the American College of Cardiology or the European Society of Cardiology or thresholds for the inverted leads based on a population study from Scotland.

Results

The addition of −V1, −V2, −V3, −aVL, −I, aVR, and −III increased sensitivity from 61% to 78% (P ≤ .01) and decreased specificity from 96% to 93% (P = .06).

Conclusions

Addition of 7 leads from the 24-lead ECG, thus creating a 19-lead ECG, was found optimal for attaining high sensitivity while retaining high specificity when compared with the performance of the standard 12-lead ECG.     

Addition of right-sided and posterior precordial leads during stress testing

Background

Exercise treadmill testing has limited sensitivity for the detection of coronary artery disease, frequently requiring the addition of imaging modalities to enhance the predictive value of the test. Recently, there has been interest in using nonstandard electrocardiographic (ECG) leads during exercise testing.

Methods

We consecutively enrolled all patients undergoing exercise myocardial imaging with four additional leads recorded (V₄R, V₇, V₈, and V₉). The test characteristics of the 12-lead, the 15-lead (12-lead, V₇, V₈, V₉), and the 16-lead (12-lead, V₄R, V₇, V₈, V₉) ECGs were compared with stress imaging in all patients. In the subset of patients who underwent angiography within 60 days of stress testing, these lead arrays were compared with the catheterization findings.

Results

There were 727 subjects who met entry criteria. The mean age was 58.5 ± 12.3 years, and 366 (50.3%) were women. Pretest probability for disease was high in 241 (33.1%), intermediate in 347 (47.7%), and low in 139 (19.1%). A total of 166 subjects had an abnormal 12-lead ECG during exercise. The addition of 3 posterior leads to the standard 12-lead ECG resulted in 7 additional subjects having an abnormal electrocardiographic response to exercise. The addition of V₄R resulted in only 1 additional patient having an abnormal ECG during exercise. The sensitivity of the ECG for detecting ischemia as determined by stress imaging was 36.6%, 39.2%, and 40.0% (P = NS) for the 12-lead, 15-lead, and 16-lead ECGs, respectively. In those with catheterization data (n = 123), the sensitivity for determining obstructive coronary artery disease was 43.5%, 45.2%, and 45.2% (P = NS) for the 12-lead, 15-lead, and 16-lead ECGs, respectively. The sensitivity of imaging modalities was 77.4% when compared with catheterization.

Conclusions

In patients undergoing stress imaging studies, the addition of right-sided and posterior leads did not significantly increase the sensitivity of the ECG for the detection of myocardial ischemia. Additional leads should not be used to replace imaging modalities for the detection of coronary artery disease.     

Temporal and postural variation of 12-lead high-frequency QRS electrocardiographic signals in asymptomatic individuals

Because changes in the 12-lead high-frequency QRS electrocardiogram (HF QRS ECG) more sensitively identify myocardial ischemia than do changes in the ST segments of the conventional ECG, it is important that changes in HF QRS signals that are merely physiological be distinguishable from those that are potentially pathological. We therefore studied the temporal variation of HF QRS measures such as root mean square (RMS) voltage and the presence vs absence of reduced amplitude zones (RAZs) in 107 asymptomatic individuals in the supine position during a brief period of ECG monitoring. In addition, to ascertain the effects of posture on the 12-lead HF QRS ECG, we collected additional seated data from 25 of these individuals and estimated the fifth and 95th percentile of the percent relative change between the supine and seated measurements. In all cases, variation of HF QRS parameters decreased as the number of beats in the signal average increased. For example, in the supine position, the 95th percentile of the percent relative change between consecutive within-lead measurements of RMS voltage for a 50-beat signal average was 12.3% but decreased to 11.7%, 11.2%, and 10.7% for 75, 100, and 150 beat signal averages, respectively (P < .01). After transition from the supine to the seated upright position, changes in some measures of HF QRS were statistically significant, with RMS voltage decreasing significantly in lead V₃ and with the number of RAZs lost in the 12-lead HF QRS ECG significantly exceeding the number of RAZs gained. We conclude that most measures of HF QRS ECG are sufficiently stable for routine continuous monitoring.     

93例急性心肌梗死患者的心电图及冠脉造影分析

目的探讨急性心肌梗死患者心电图sT改变的导联与冠状动脉罪犯血管的关系。方法对93例急性心肌梗死患者心电图ST段改变与选择性冠状动脉造影结果进行对比分析。结果心电图V1-V4sT抬高伴Ⅱ、Ⅲ、aVFST段下移的罪犯血管主要为左前降支（LAD）,少数前壁心肌梗死伴下壁sT段抬高;Ⅱ、Ⅲ、aVFST抬高伴V1-V4 ST段下移的主要罪犯血管为右冠状动脉（RCA）,少部分为左回旋支（LCX）,极少部分为LAD;胸前导联T高尖与ST抬高导联不一致可排除LAD;高侧壁Ⅰ、AVLST段抬高多数罪犯血管为LCX。结论心电图ST改变的导联对急性心肌梗死罪犯血管能进行初步预测。     

Monitoring of ischemia during percutaneous coronary angioplasty: Influence of guidewire,balloon placement,and lead selection

We examined the sensitivity of the surface 12-lead electrocardiogram (ECG) for detecting ischemia during guidewire and deflated balloon passage as well as during balloon inflation in proximal epicardial stenoses during percutaneous transluminal coronary angioplasty (PTCA) of 55 patients. Ischemia (ST change ? 0.1 mV) by 12-lead ECG was detected in 28% of patients after guidewire passage, in 50% after deflated balloon passage, and in 76% during balloon inflation vs. 17%, 14%, and 50%, respectively, by limb lead monitoring alone. The best single lead for detecting ischemia during PTCA was V₂ for left anterior descending and circumflex and III for right coronary artery inflations. The addition of a selected second precordial lead further enhanced ischemia monitoring. We conclude that ischemia is common during PTCA even during wire and deflated balloon passage, that the 12-lead ECG is more sensitive for monitoring ischemia during PTCA than conventional techniques, and that laboratories can optimize their ability to detect ischemia during PTCA by selecting appropriate leads.     

A new ECG algorithm for the localization of accessory pathways using only the polarity of the QRS complex

A new algorithm is proposed for localization of accessory atrioventricular pathways by use of a 12-lead electrocardiogram (ECG). The polarity of the QRS complex in leads III, V₁, and V₂ from 102 patients with Wolff-Parkinson-White syndrome with manifested preexcitation who underwent successful radiofrequency catheter ablation was analyzed. Accessory pathways on the right side of the heart were localized to three regions around the tricuspid annulus, and left-sided pathways were localized to two regions around the mitral valve annulus. In 42 of 46 patients (91%) with left posterolateral accessory pathways, a common characteristic of the ECG was a positive QRS complex in leads III and V₁ (sensitivity 91%, specificity 95%). Of 19 patients with left inferior paraseptal or inferior accessory pathways, 16 (84%) had a negative QRS complex in lead III and a positive QRS complex in lead V₁ (sensitivity 84%, specificity 98%). All six patients with right anterosuperior paraseptal accessory pathways had a positive QRS complex in lead III but a negative QRS complex in lead V₁ (sensitivity 100%, specificity 97%). The 25 patients with right inferior paraseptal or inferior accessory pathways had a negative or isodiphasic QRS complex in leads III and V₁, but the QRS complex was positive in lead V₂ in 21 (84%) of these patients (sensitivity 84%, specificity 100%). Finally, five of the six patients (83%) with right anterior accessory pathways had a negative QRS complex in leads III, V₁, and V₂ (sensitivity 83%, specificity 96%). With the algorithm, the localization of accessory pathways was thus identified in 90 of the 102 patients (88%).     

12导联同步动态心电图在冠心病心肌缺血诊断中的应用

目的探讨12导联同步动态心电图（DCG）在冠心病心肌缺血诊断中的价值,进一步推广在基层医院中的应用。方法选取本院就诊中疑诊为冠心病的250例作为研究对象,同时行12导联和3导联同步DCG24h监测,收集相关信息,进行统计学分析。结果 12导联同步DCG对心肌缺血诊断的阳性率明显高于3导联者,两者之间有显著差异（P〈0.05）;12导联同步DCG对下壁、侧壁心肌缺血的诊断优于3导联同步记录。结论 12导联描记在冠心病心肌缺血诊断上明显优于3导联记录,可以减少冠心病的漏诊率。     

Abnormal intra-QRS potentials associated with percutaneous transluminal coronary angiography-induced transient myocardial ischemia

This article introduces a novel concept of abnormal intra-QRS potentials (AIQPs) associated with myocardial ischemia. AIQPs are microvolt-level potentials—subtle alterations in the QRS of the high-resolution electrocardiogram (ECG)—isolated from the unfiltered signal-averaged ECG (SAECG) by a method of mathematical modeling. The aims of the study were (1) to determine the characteristics of potentials in the SAECG related to ischemically altered activation during percutaneous transluminal coronary angiography (PTCA), (2) to determine their relationship with standard 12-lead ECG variables, and (3) to investigate whether AIQPs have a specific pathophysiologic basis in myocardial ischemia. Continuous high-resolution ECG data were acquired from 12 patients before, during, and after PTCA. SAECGs were computed every 60 seconds using an enhanced method of signal averaging. AIQP, ST-segment deviation, and changes in standard ECG QRS duration were measured in each 1-minute SAECG. AIQP amplitudes increased significantly during balloon inflation, compared with the preinflation state. AIQPs exhibited a greater prevalence (12 of 12 patients) than ST-segment deviation changes of more than 100 μV (7 of 12 patients), or measurable changes in standard QRS duration (4 of 12 patients). In patients with significant changes in 12-lead ECG variables during balloon inflation, AIQPs were strongly correlated with both ST-segment and QRS-duration changes. AIQP timing was correlated with the artery occluded, suggesting a specific, ischemia-influenced origin of the signal. AIQPs show promise as a time-localized, sensitive new ECG marker of ischemically altered ventricular activation.     

ECG Diagnosis of Coronary Artery Disease

Objective: In order to assess the diagnostic accuracy of ST depression in the diagnosis of coronary artery disease (CAD) in patients with suspected myocardial ischemia we compared ST depression in 3-lead ambulatory ECG (AECG) with that of exercise tolerance testing (ETT). Methods: Significant coronary artery stenosis in coronary angiography was used as a standard reference. ST analysis could be performed in 106 of the investigated 113 patients, all with suspected CAD. One person with left bundle branch block was excluded from the ST analysis, and six persons could not perform ETT. Results: Seventy-eight of the 106 patients had at least one significant stenosis (> 70% narrowing) and 28 had no stenosis according to coronary angiography. The sensitivity for AECG was 62% and for ETT it was 63%, the specificity for AECG was 79% and for ETT the specificity was 57%. The accuracy for AECG was 66%, and for ETT it was 61%. We also evaluated late potentials (LPs) from the AECG tapes in order to correlate LP to left ventricular function (LVF), myocardial infarction (Ml), and/or CAD. We found that LP correlates better to advanced CAD than to Ml or LVF. Conclusion: The accuracy of ST diagnosis of CAD in patients with suspected myocardial ischemia using AECG was equal to that of a maximal ETT. LP finding from an AECG tape may support the argument for CAD in patients with ST depressions at AECG.     

Optimization of the precordial leads of the 12-lead electrocardiogram may improve detection of ST-segment elevation myocardial infarction

Background

For the assessment of patients with chest pain, the 12-lead electrocardiogram (ECG) is the initial investigation. Major management decisions are based on the ECG findings, both for attempted coronary artery revascularization and risk stratification. The aim of this study was to determine if the current 6 precordial leads (V₁-V₆) are optimally located for the detection of ST-segment elevation in ST-segment elevation myocardial infarction (STEMI).

Methods

We analyzed 528 (38% anterior [200], 44% inferior [233], and 18% lateral [95]) patients with STEMI with both a 12-lead ECG and an 80-lead body surface map (BSM) ECG (Prime ECG, Heartscape Technologies, Bangor, Northern Ireland). Body surface map was recorded within 15 minutes of the 12-lead ECG during the acute event and before revascularization. ST-segment elevation of each lead on the BSM was compared with the corresponding 12-lead precordial leads (V₁-V₆) for anterior STEMI. In addition, for lateral STEMI, leads I and aVL of the BSM were also compared; and limb leads II, III, aVF of the BSM were compared with inferior unipolar BSM leads for inferior STEMI. Leads with the greatest mean ST-segment elevation were selected, and significance was determined by analysis of variance of the mean ST segment.

Results

For anterior STEMI, leads V₁, V₂, 32, 42, 51, and 57 had the greatest mean ST elevation. These leads are located in the same horizontal plane as that of V₁ and V₂. Lead 32 had a significantly greater mean ST elevation than the corresponding precordial lead V₃ (P = .012); and leads 42, 51, and 57 were also significantly greater than corresponding leads V₄, V₅, V₆, respectively (P < .001). Similar findings were also found for lateral STEMI. For inferior STEMI, the limb leads of the BSM (II, III, and aVF) had the greatest mean ST-segment elevation; and lead III was significantly superior to the inferior unipolar leads (7, 17, 27, 37, 47, 55, and 61) of the BSM (P < .001).

Conclusion

Leads placed on a horizontal strip, in line with leads V₁ and V₂, provided the optimal placement for the diagnosis of anterior and lateral STEMI and appear superior to leads V₃, V₄, V₅, and V₆. This is of significant clinical interest, not only for ease and replication of lead placement but also may lead to increased recruitment of patients eligible for revascularization with none or borderline ST-segment elevation on the initial 12-lead ECG.     

Comparison of epicardial potential maps derived from the 12-lead electrocardiograms with scintigraphic images during controlled myocardial ischemia

Our aim was to cross-validate electrocardiographic (ECG) and scintigraphic imaging of acute myocardial ischemia. The former method was based on inverse calculation of heart-surface potentials from the body-surface ECGs, and the latter, on a single photon emission computed tomography (SPECT). A boundary-element torso model with 352 body-surface and 202 heart-surface nodes was used to perform the ECG inverse solution. Potentials at 352 body-surface nodes were calculated from those acquired at 12-lead ECG measurement sites using regression coefficients developed from a design set (n = 892) of body-surface potential mapping (BSPM) data. The test set (n = 18) consisted of BSPM data from patients who underwent a balloon-inflation angioplasty of either the left anterior descending coronary artery (LAD) (n = 7), left circumflex coronary artery (LCx) (n = 2), or the right coronary artery (RCA) (n = 9). Body-surface potential mapping distributions at J point for 352 nodes were estimated from the 12-lead ECG, and an agreement with those estimated from 120 leads was assessed by a correlation coefficient (CC) (in percent). These estimates yielded very similar BSPM distributions, with a CC of 91.0% ± 8.1% (mean ± SD) for the entire test set and 94.1% ± 1.4%, 96.7% ± 0.8%, and 87.4% ± 10.3% for LAD, LCx, and RCA subgroups, respectively. Corresponding heart-surface potential distributions obtained by inverse solution correlated with a lower CC of 69.3% ± 18.0% overall and 73.7% ± 10.8%, 84.7% ± 1.1%, and 62.6% ± 21.8%, respectively, for subgroups. Bull's-eye displays of heart-surface potentials calculated from estimated BSPM distributions had an area of positive potentials that qualitatively corresponded, in general, with the underperfused territory suggested by SPECT images. For the LAD and LCx groups, all 9 ECG-derived bull's-eye images indicated the expected territory; for the RCA group, 6 of 9 ECG-derived images were as expected; 2 of 3 misclassified cases had very small ECG changes in response to coronary-artery occlusion, and their SPECT images showed indiscernible patterns. In conclusion, our findings demonstrate that noninvasive ECG imaging based on just the 12-lead ECG might provide useful estimates of the regions of myocardial ischemia that agree with those provided by scintigraphic techniques.     

Electrocardiographic ST-segment changes during acute myocardial ischemia

The recognition and management of patients with acute coronary syndromes has relied to a large extent onthe standard 12-lead electrocardiogram (ECG) for assessing ST-segment changes associated with ischemia.The purpose of this review is to show both the capabilities and the limitations of the 12-lead ECG in recognizingischemia, and to seek alternative electrocardiographic leads, optimized for detection of ischemia originating indifferent regions of the ventricular myocardium. Three such leads are proposed—based on the results obtainedby electrocardiographic body-surface mapping performed during ischemia induced by balloon-inflation coronaryangioplasty. A survey of recent clinical studies shows that the electrocardiographic manifestations of acutemyocardial ischemia observed during coronary angioplasty are in agreement with the ST-segment measurements inadmission ECGs of patients with acute myocardial infarction.     

再灌注治疗对急性心肌梗死患者QRS离散度的影响

目的：探讨成功静脉溶栓或经皮腔内冠状动脉成形术（PTCA）治疗对急性心肌梗死患QRS离散度（QRSd)的影响。方法：对象为60例发病6小时内成功进行静脉溶栓或PTCA术治疗的急性心肌梗死患。其中静脉尿激酶溶栓44例，直接接受PTCA及冠状动脉内支架术治疗16例。60例患均接受体表12导同步心电图QRSd的检测。结果：与治疗前相比，成功再灌注（静脉溶栓或PTCA术）治疗的急性心肌梗死患的QRSd明显减少（P＜0．05）。结论：成功再灌注治疗可改善急性心肌缺血及心室除极的不一致，从而明显减少QRSd。     

Electrocardiographic scores of severity and acuteness of myocardial ischemia predict myocardial salvage in patients with anterior ST-segment elevation myocardial infarction

Background

Terminal “QRS distortion” on the electrocardiogram (ECG) (based on Sclarovsky-Birnbaum's Grades of Ischemia Score) is a sign of severe ischemia, associated with adverse cardiovascular outcome in ST-segment elevation myocardial infarction (STEMI). In addition, ECG indices of the acuteness of ischemia (based on Anderson-Wilkins Acuteness Score) indicate myocardial salvage potential. We assessed whether severe ischemia with or without acute ischemia is predictive of infarct size (IS), myocardial salvage index (MSI) and left ventricular ejection fraction (LVEF) in anterior versus inferior infarct locations.

QRS prolongation on the signal-averaged electrocardiogram versus st-segment changes on the 12-lead electrocardiogram: Which is the most sensitive electrocardiographic marker of myocardial ischemia?

BACKGROUND: ST-segment changes and QRS prolongation are electrocardiographic (ECG) markers of myocardial ischemia. HYPOTHESIS: This study was undertaken to investigate the appearance of QRS duration changes with or without concomitant ST-segment changes during a typical anginal episode. METHODS: For this purpose, 126 patients underwent 12-lead surface ECG and signal-averaged electrocardiogram (SAECG) during typical anginal pain as well as at the time the patient was asymptomatic. In both periods, QRS duration and ST-segment changes were evaluated. All patients underwent cardiac catheterization. RESULTS: Of the 126 patients, 108 (86%) had coronary artery disease (CAD), whereas the remaining 18 (14%) patients had normal coronary arteriograms. During typical anginal pain, 75 of the 108 (70%) patients with CAD and 2 of the 18 (11%) patients with normal coronary arteriograms developed QRS prolongation, whereas 60 of the 108 (56%) patients with CAD and 2 of the 18 (11%) patients with normal coronary vessels developed ST-segment changes. Thus, the sensitivities of QRS prolongation measured by SAECG and of ST-segment changes on the surface ECG for the detection of myocardial ischemia were found to be 70 and 56%, respectively, (p < 0.01), whereas the specificities were both found to be 89% (p = NS). CONCLUSIONS: During typical anginal pain, QRS prolongation on the SAECG is more sensitive than are ST-segment changes on the ECG for the detection of myocardial ischemia.     

Electrocardiographic predictors of cardiovascular outcome in women: the National Heart, Lung, and Blood Institute-sponsored Women's Ischemia Syndrome Evaluation (WISE) study

OBJECTIVES: We sought to analyze the value of infrequently measured parameters of the 12-lead electrocardiogram (ECG) in predicting cardiovascular events in women with suspected myocardial ischemia who were referred for cardiac catheterization. BACKGROUND: Routinely analyzed ECG parameters have low predictive value for cardiovascular events in women with preserved left ventricular function and suspected myocardial ischemia. The predictive value of ECG parameters for cardiovascular disease has not been fully determined. METHODS: Women enrolled in the National Heart, Lung, and Blood Institute-sponsored Women's Ischemia Syndrome Evaluation (WISE) study who had complete digital 12-lead ECG and quantitative angiography data were studied. Clinical and ECG predictors of cardiovascular disease events, defined as death, congestive heart failure, and non-fatal myocardial infarction, were determined. RESULTS: Of 143 women with ECG and angiographic data (mean age 59 +/- 13 years, left ventricular ejection fraction 64.1 +/- 8.6%), 13% had events during a mean follow-up period of 3.3 +/- 1.6 years. Independent predictors of event occurrences included a wider QRS-T angle (i.e., the spatial electrical angle between the QRS complex and the T-wave; p = 0.0005), wider QRS complex (p = 0.004), longer QTrr (i.e., age- and gender-adjusted QT interval; p = 0.0004), a more depressed ST-segment in precordial lead V5 (p = 0.0002), and a higher coronary artery disease severity score (p = 0.02). CONCLUSIONS: Several 12-lead ECG parameters, such as the QRS-T angle and the QRS and QTrr duration, are predictive of future cardiovascular events in women with suspected myocardial ischemia.     

Prevalence and Correlates of Ischemic ECG Findings among Adults With and Without HIV in Tanzania

Introduction:HIV confers increased risk of myocardial infarction (MI), but there has been little study of ischemic electrocardiogram (ECG) findings among people with HIV in sub-Saharan Africa.Objectives:To compare the prevalence of ischemic ECG findings among Tanzanians with and without HIV and to identify correlates of ischemic ECG changes among Tanzanians with HIV.Methods:Consecutive adults presenting for routine HIV care at a Tanzanian clinic were enrolled. Age- and sex-matched HIV-uninfected controls were enrolled from a nearby general clinic. All participants completed a standardized health questionnaire and underwent 12-lead resting ECG testing, which was adjudicated by independent physicians. Prior MI was defined as pathologic Q-waves in contiguous leads, and myocardial ischemia was defined as ST-segment depression or T-wave inversion in contiguous leads. Pearson’s chi-squared test was used to compare the prevalence of ECG findings among those with and without HIV and multivariate logistic regression was performed to identify correlates of prior MI among all participants.Results:Of 497 participants with HIV and 497 without HIV, 272 (27.8%) were males and mean (sd) age was 45.2(12.0) years. ECG findings suggestive of prior MI (11.1% vs 2.4%, OR 4.97, 95% CI: 2.71–9.89, p < 0.001), and myocardial ischemia (18.7% vs 12.1% OR 1.67, 95% CI: 1.18–2.39, p = 0.004) were significantly more common among participants with HIV. On multivariate analysis, ECG findings suggestive of prior MI among all participants were associated with HIV infection (OR 4.73, 95% CI: 2.51–9.63, p = 0.030) and self-reported family history of MI or stroke (OR 1.96, 95% CI: 1.08–3.46, p = 0.023).Conclusions:There may be a large burden of ischemic heart disease among adults with HIV in Tanzania, and ECG findings suggestive of coronary artery disease are significantly more common among Tanzanians with HIV than those without HIV.     

Values of electrocardiography and two-dimensional echocardiography to identify myocardial infarction due to left circumflex and right coronary artery disease

To investigate the value of the 12-lead ECG and two-dimensional echocardiography (2DE) in the distinction of left circumflex (LCX) from right coronary artery (RCA) disease, we analyzed the location of Q waves, infarct lesions, and coronary artery narrowings in 26 patients with angiographically documented single-vessel disease. Q waves in leads II, III, and aVF were associated with the posterior wall (PW) lesions at the papillary muscle level. Extensive lesions from the PW to the posterior septum (PS) identified RCA disease, while extension to the lateral wall (LW) identified LCX disease. Eleven of 12 patients with high posterior infarction (tall R wave in V₁) were found to have extensive LW lesions and 10 of these had coronary narrowings in or proximal to the obtuse marginal branch of LCX. All 6 patients with high posterior infarction and high lateral infarction (Q in I or aVL) had infarct lesions extending from the LW to the anterior wall (AW) and were associated with LCX disease with a large obtuse marginal branch. Of 10 patients with Q waves in V₆, the apical LW and PW were involved in 7 and either segment in 3. Nine of these 10 patients had LCX disease. It is concluded that the location of Q waves in inferior infarction could aid in recognizing infarct extension and underlying coronary artery disease.     

Exercise-induced prolongation of the infarct-related Q-waves as a marker of myocardial viability in the infarcted area

OBJECTIVE: It is known that exercise-induced ischemia in patients with coronary artery disease (CAD) may produce QRS prolongation in the surface electrocardiogram (ECG). To investigate the presence of exercise-induced Q-wave prolongation in patients with single-vessel CAD and Q-wave myocardial infarction (MI), in association with the presence of reversible perfusion defects during thallium scintigraphy in the infarcted area. METHODS: 107 consecutive patients (89 males, mean age 56+/-8 years) were evaluated. All patients underwent coronary arteriography, maximal treadmill exercise testing and thallium-201 scintigraphy. Q-wave duration was measured both before exercise testing and during maximal heart rate from 12-lead ECGs recorded with a paper speed of 50 mm/s. RESULTS: Only 57 out of the 107 studied patients showed reversible perfusion defects in the infarcted area during thallium scintigraphy. Q-wave duration was significantly increased from the resting to the stress ECG (DeltaQ-wave duration) in patients with reversible perfusion defects in the infarcted areas (10+/-13 ms), but not in patients with fixed defects in the infarcted zone (-2.0+/-5 ms, p<0.01). The sensitivities and the specificities of Q-wave prolongation, ST segment elevation, and the combination of ST segment elevation with ST segment depression in the reciprocal leads for the detection of myocardial viability in the infarcted area were 82%, 48%, 29% and 88%, 50%, and 90%, respectively. CONCLUSIONS: Exercise-induced Q-wave prolongation is demonstrated in those patients with single-vessel CAD and a recent MI who show reversible perfusion defects in thallium scintigraphy. Exercise-induced Q-wave prolongation was found to be a sensitive and specific ECG marker for the detection of myocardial viability in the infarcted area.