Best leads in the standard electrocardiogram for the emergency detection of acute coronary syndrome

Background and Purpose

The purpose of this study was to determine which leads in the standard 12-lead electrocardiogram (ECG) are the best for detecting acute coronary syndrome (ACS) among chest pain patients in the emergency department.

Methods

Neural network classifiers were used to determine the predictive capability of individual leads and combinations of leads from 862 ECGs from chest pain patients in the emergency department at Lund University Hospital.

Results

The best individual lead was aVL, with an area under the receiver operating characteristic curve of 75.5%. The best 3-lead combination was III, aVL, and V₂, with a receiver operating characteristic area of 82.0%, compared with the 12-lead ECG performance of 80.5%.

Conclusions

Our results indicate that leads III, aVL, and V2 are sufficient for computerized prediction of ACS. The present results are likely important in situations where the 12-lead ECG is impractical and for the creation of clinical decision support systems for ECG prediction of ACS.     

Where do derived precordial leads fail?

A 12-lead electrocardiogram (ECG) reconstructed from a reduced subset of leads is desired in continued arrhythmia and ST monitoring for less tangled wires and increased patient comfort. However, the impact of reconstructed 12-lead lead ECG on clinical ECG diagnosis has not been studied thoroughly. This study compares the differences between recorded and reconstructed 12-lead diagnostic ECG interpretation with 2 commonly used configurations: reconstruct precordial leads V₂, V₃, V₅, and V₆ from V₁,V₄, or reconstruct V₁, V₃, V₄, and V₆ from V₂,V₅. Limb leads are recorded in both configurations.A total of 1785 ECGs were randomly selected from a large database of 50000 ECGs consecutively collected from 2 teaching hospitals. ECGs with extreme artifact and paced rhythm were excluded. Manual ECG annotations by 2 cardiologists were categorized and used in testing. The Philips resting 12-lead ECG algorithm was used to generate computer measurements and interpretations for comparison. Results were compared for both arrhythmia and morphology categories with high prevalence interpretations including atrial fibrillation, anterior myocardial infarct, right bundle-branch block, left bundle-branch block, left atrial enlargement, and left ventricular hypertrophy. Sensitivity and specificity were calculated for each reconstruction configuration in these arrhythmia and morphology categories.Compared to recorded 12-leads, the V₂,V₅ lead configuration shows weakness in interpretations where V₁ is important such as atrial arrhythmia, atrial enlargement, and bundle-branch blocks. The V₁,V₄ lead configuration shows a decreased sensitivity in detection of anterior myocardial infarct, left bundle-branch block (LBBB), and left ventricular hypertrophy (LVH).In conclusion, reconstructed precordial leads are not equivalent to recorded leads for clinical ECG diagnoses especially in ECGs presenting rhythm and morphology abnormalities. In addition, significant accuracy reduction in ECG interpretation is not strongly correlated with waveform differences between reconstructed and recorded 12-lead ECGs.     

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.     

Optimizing the 12-lead electrocardiogram: a data driven approach to locating alternative recording sites

Background

Despite its widespread use, the limitations of the 12-lead electrocardiogram (ECG) are undisputed. The main deficiency is that just a small area of the precordium is interrogated and for some abnormalities information may be transmitted to a region of the body surface where information is not recorded. In this study, we attempted to optimize the 12-lead ECG by using a data-driven approach to suggest alternate recording sites.

Methods

A sequential lead selection algorithm was applied to a set of 744 body surface potential maps (BSPMs), consisting of recordings from subjects with myocardial infarction, left ventricular hypertrophy, and no apparent disease. A number of scenarios were investigated in which pairs of precordial leads were repositioned; these pairs were V₃ and V₅, V₄ and V₅, and V₄ and V₆. The algorithm was also used to find optimal positions for all 6 precordial leads.

Result

Through estimation of entire surface potential distributions it was found that each of the scenarios, with 2 leads repositioned, captured more information than the standard 12-lead ECG. The scenario with V₄ and V₆ repositioned performed best with a root mean square error of 22.3 microvolts and a correlation coefficient of 0.967. This configuration also fared favorably when compared to the scenario where all 6 precordial leads were repositioned as optimizing all 6 leads offered no significant improvement.

Conclusion

This study demonstrated the use of a lead selection algorithm in enhancing the 12-lead ECG. The results also indicated that repositioning just 2 precordial leads can provide the same level of information capture as that observed when all precordial leads are optimally placed.     

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.     

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.     

Calculating Cornell voltage from nonstandard chest electrode recording site in the Reasons for Geographic And Racial Differences in Stroke study

Background

To minimize participants' burden and the need for disrobing, a 7-lead electrocardiogram (ECG) recording using a single mid-sternal chest lead was recorded at the initial stages of The REasons for Geographic And Racial Differences in Stroke (REGARDS) study. Electrocardiogram-detected left ventricular hypertrophy (ECG-LVH) by Cornell voltage (RaVL + S-wave amplitude in V₃ [SV₃]) cannot be assessed from this method because of the absence of V₃. We examined the possibility that the S-wave amplitude in the mid-sternal lead (SV) could be used as a surrogate for SV₃.

Methods

The REGARDS study is a US national study where 7-lead ECGs were performed in 8,330 (29%) participants and standard 12-lead EGCs were performed in 20?811 (71%). Cornell voltage was calculated as the sum of aVL amplitude + SV (in the 7-lead group) or SV₃ (in the 12-lead group). Logistic regression analysis was used to examine and compare the magnitude of the association between the LVH risk factors with ECG-LVH in both groups, and Cox proportional hazards analysis was used to examine and compare the hazard ratios of overall mortality and cardiovascular mortality associated with ECG-LVH in both groups.

Results

Regardless of the Cornell voltage calculation method, ECG-LVH was significantly associated with LVH risk factors; and with the exception of sex, there was no evidence of a difference in the magnitude of the association. ECG-LVH from both approaches were significantly and similarly associated with both all-cause and cardiovascular mortality.

Conclusion

ECG-LVH by Cornell voltage calculated from a 7-lead ECG (using SV in the formula) has demographic and clinical associations that are similar to that calculated from a standard 12-lead ECG (using SV₃). In epidemiologic studies recording 7-lead ECG, SV could be used as an alternative to SV₃ in the Cornell voltage formula.     

A quantitative evaluation of ST-segment changes on the 18-lead electrocardiogram during acute coronary occlusions

This study determined quantitative ST segment changes on the 18-lead electrocardiogram (ECG) during occlusions in each of the coronary arteries.

Methods

Continuous 18-lead ECGs, including standard 12 leads, posterior (V_7-9), and right ventricular (RV) leads (V_3-5R) were recorded for 155 subjects undergoing percutaneous coronary occlusions, the maximum intervention.

Results

During 58 left anterior descending (LAD) coronary occlusions, the maximum ST elevation and depression were in V₃ (4.2mm) and III (−0.9mm), respectively. During 44 right coronary artery (RCA) occlusions, the maximum ST elevation and depression were in III (2.2mm) and aVL (−1.4mm), respectively. During 53 left circumflex (LCX) occlusions, the maximum ST elevation and depression were in V₇ (0.8mm) and V₂ (−1.6mm), respectively.

Conclusions

ST elevation often occurred in the anteroapical (V₁-V₆), lateral (I, aVL), and RV lead V_3R during LAD occlusions; in the inferior, RV, and posterior leads during RCA occlusions; and in the posterior, inferior, and apical leads (V₅-V₆) during LCX occlusions.     

R-wave amplitude changes measured by electrocardiography during early transmural ischemia

Background

Changes in the amplitude of the R wave (RWA) on the electrocardiogram (ECG) have been described during acute myocardial ischemia and infarction. However, this has not been well studied in a controlled setting. We hypothesized that significant increase in RWA occurs during early transmural myocardial ischemia.

Methods

We prospectively evaluated changes in RWA in 50 patients during brief episodes of transmural ischemia induced by first balloon occlusion (mean, 38 seconds at 6-10 atmospheric pressures) during elective percutaneous coronary intervention. We recorded 12-lead ECGs at 20-second intervals before and during balloon inflation in 16 right coronary arteries, 14 left circumflex arteries, and 20 left anterior descending arteries. R wave amplitude was digitally measured in each of the 12 leads in every ECG using the ECG interval editor (General Electric HC, Menomonee Falls, WI). Intracoronary (IC) ECGs were also recorded in 4 patients. The mean of the RWA in each lead before balloon inflation was compared to the mean RWA during balloon inflation.

Results

R wave amplitude significantly increased during balloon inflation from baseline in limb leads I, II, aVL, and all the precordial leads with the exception of lead V₁. The RWA increase did not reach statistical significance in leads III, aVF, and V₁. Mean RWA increase was consistent in all leads except aVR during the brief episodes of ischemia during initial balloon inflation because of the inverse polarity of this lead. The increase in RWA was seen in most patients (mean, 75%) in whom transmural ischemia was induced by first balloon inflation. Besides, the RWA showed an increase from baseline in 3 patients who had IC-lead recordings.

Conclusion

R wave amplitude increases significantly in precordial leads (V₂-V₆) and limb leads (I, II, aVL) of the surface ECG during brief episodes of transmural ischemia. The increase in RWA might be consistent with the expansion of the left ventricular cavity during ischemia and/or alterations in conduction that are intrinsic to the myocardium.     

EASI-Derived vs standard 12-lead electrocardiogram for Selvester QRS score estimations of chronic myocardial infarct size, using cardiac magnetic resonance imaging as gold standard

Background

The size of myocardial infarction (MI) is of significance for the prognosis. Selvester scores might be valuable for this estimation.

Objective

To compare the differences in Selvester scores for chronic MI provided from standard and EASI-derived 12-lead electrocardiograms (ECGs) and to compare these scores to the MI size measured by delayed-enhancement magnetic resonance imaging (DE-MRI).

Methods

Thirty-seven patients were studied. In connection with their DE-MRI scan follow-up after chest pain, body surface potential mapping was performed. Standard and EASI 12-lead ECGs were constructed from the maps. Two investigators manually performed the measurements required for scoring with the Selvester system using a quad-plot format of the ECGs. One of the investigators repeated this once for the standard leads.

Results

The differences between the 2 ECG estimations of MRI-measured MI size were not statistically significant. Neither the association nor the agreement between MRI and EASI-lead measurements or between MRI and standard-lead measurements were very strong.

Conclusions

The differences between ECG and MRI measurements of MI size indicate that both methods may need improvement.     

Value of Posterior and Right Ventricular Leads in Comparison to the Standard 12-Lead Electrocardiogram in Evaluation of ST-Segment Elevation in Suspected Acute Myocardial Infarction

In this multicenter prospective trial, we studied posterior (V₇ to V₉) and right ventricular (V₄R to V₆R) leads to assess their accuracy compared with standard 12-lead electrocardiograms (ECGs) for the diagnosis of acute myocardial infarction (AMI). Patients aged >34 years with suspected AMI received posterior and right ventricular leads immediately after the initial 12-lead ECG. ST elevation of 0.1 mV in 2 leads was blindly determined and inter-rater reliability estimated. AMI was diagnosed by World Health Organization criteria. The diagnostic value of nonstandard leads was determined when 12-lead ST elevation was absent and present and multivariate stepwise regression analysis was also performed. Of 533 study patients, 64.7% (345 of 533) had AMI and 24.8% received thrombolytic therapy. Posterior and right ventricular leads increased sensitivity for AMI by 8.4% (

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) but decreased specificity by 7.0% (

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). The likelihood ratios of a positive test for 12, 12 + posterior, and 12 + right ventricular ECGs were 6.4, 5.6, and 4.5, respectively. Increased AMI rates (positive predictive values) were found when ST elevation was present on 6 nonstandard leads (69.1%), on 12 leads only (88.4%), and on both 6 and 12 leads (96.8%; p <0.001). Treatment rates with thrombolytic therapy increased in parallel with this electrocardiographic gradient. Logistic regression analysis showed that 4 leads were independently predictive of AMI (p <0.001): leads I, II, V₃, V₅R; V₉ approached statistical significance (

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). The standard ECG is not optimal for detecting ST-segment elevation in AMI, but its accuracy is only modestly improved by the addition of posterior and right ventricular leads.In this multicenter prospective trial, 0.1 mV of ST-segment elevation in posterior (V₇ to V₉) and right ventricular (V₄R to V₆R) leads was found to increase the sensitivity of the electrocardiogram for acute myocardial infarction by 8.4% (

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), but decrease specificity by 7.0% (

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); logistic regression analysis showed that 4 leads were predictive of AMI at p <0.001: I, II, V₃, V₅; V₉ approached statistical significance (

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). The standard electrocardiogram is not optimal for detecting ST elevation in acute myocardial infarction, but its accuracy is only modestly improved by the addition of posterior and right ventricular leads.     

Value of the 12-lead resting electrocardiogram for the diagnosis of previous myocardial infarction in paced patients

Aim

This study was conducted to assess the clinical value of the 12-lead electrocardiogram (ECG) for the diagnosis of previous myocardial infarction (MI) in permanently paced patients.

Methods

A total of 107 unselected patients with permanent pacemakers were retrospectively studied and divided into 3 groups: group 1 (control group): 38 patients without a history of MI (mean age, 67 ± 16 years; 20 men; ejection fraction 63% ± 8%); group 2: 44 patients (mean age, 72 ± 11 years; 41 men) with documented previous MI (21 anterior, 23 inferior; ejection fraction 38% ± 13%; P < .0001 vs group 1); group 3: 25 patients (mean age, 71 ± 14 years; 24 men) with biventricular pacing for severe heart failure (16 ischemic, 9 nonischemic; ejection fraction 28% ± 8%; P = .001 vs group 2, P < .0001 vs group 1). A surface 12-lead ECG with full ventricular capture was used for analysis. Comparing group 1 and group 2, the sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy of 5 criteria was calculated: (1) Cabrera's sign (notching in the ascending limb of the S wave in lead V₃, V₄, or V₅); (2) Chapman's sign (notching of the R wave in lead I, aVL, or V₆); (3) presence of a qR in lead I, aVL, or V₆; (4) notching of QRS in lead II, III, or aVF; (5) presence of a qR in lead II, III, or aVF.

Results

To detect prior MI, sensitivity was moderate for Cabrera's sign (63.6%) and poor for all other ECG criteria ranging from 9.1% to 40.9%. Specificity was relatively high for all ECG criteria ranging from 81.6% to 100%. Combining all 5 ECG signs increased sensitivity to 86.4%, with a specificity of 65.8% and an overall accuracy of 76.8% for the diagnosis of previous MI. None of the 5 criteria was particularly useful to assess the site of prior MI.In patients with biventricular pacing, the accuracy of the 5 ECG criteria was poor and the presence of a qR wave in lead I, aVL, or V6 appears nonspecific and related to pacing site.

Conclusion

The ECG diagnosis of previous MI in paced patients remains a difficult challenge but the presence of 1 or more of the aforementioned ECG criteria may be clinically useful to detect previous MI, suggesting that these ECG signs should be widely taught during medical training. However, in patients with biventricular pacing, these ECG signs are of no value.     

Diagnostic accuracy of a new detection algorithm for atrial fibrillation in cardiac telemonitoring with portable electrocardiogram devices

Background

Telemedical approaches targeting cardiac outpatients try to include electrocardiogram (ECG) analysis. Increasing numbers of monitored patients require automated preanalysis of the ECG to prioritize the evaluation for the clinical professional to enable an efficient intervention.

Methods

ECGs were recorded from 60 patients, both with a standard 12-lead ECG and with a new handheld ECG device having dry electrodes for direct skin contact. Recordings of the handheld device were automatically analyzed by a new algorithm. The 12-lead recordings were evaluated by a blinded cardiologist and then compared to the automated analysis of the handheld ECG. Sensitivity and specificity of the algorithm for the detection of atrial fibrillation (AF) were calculated.

Results

A total of 60 ECG strips having 122 ± 36 beats were registered. One hundred percent of the ECG strips were sufficient for automated heart rate count; 96.6%, for automated AF analysis; and 80%, for PQ, QRS, and QTc time measurements. AF detection had a sensitivity of 92.9% and a specificity of 90.9%. There was no difference in heart rate count between automated and manual analysis (median, 71 vs 70 beats per minute; P = .51). Automated measurements of a summary complex showed no difference for PQ time (165 vs 161 milliseconds, P = .50) but overestimated QRS (119 vs 90 milliseconds, P = .001) and QTc (489 vs 417 milliseconds, P < .001) times as compared to the 12-lead recordings analyzed manually.

Conclusion

The new algorithm is suitable for automated preanalysis of the ECG data with regard to AF. It could be used for rapid selection of ECGs with relevant rhythm abnormalities from a large pool. Electrocardiographic data remain to be evaluated by health care professionals for exact diagnosis.     

Mirror image electrocardiograms and additional electrocardiographic leads: new wine in old wineskins?

Background

Mirror image electrocardiograms (ECGs), obtained by inverting the original signals, and additional precordial leads have been proposed as means to improve ECG diagnosis. The theoretical backgrounds of these proposals are discussed.

Methods

In 746 body surface potential maps, the mirror areas of the 6 precordial leads, V₃R, and 2 more leads higher up and 1 lower down the thorax have been determined. The similarity between the original signal and its mirror image was expressed by a similarity index. This was done separately for QRS and ST-T; for the first and second parts of QRS; and for the categories normal, left ventricular hypertrophy, and infarct.

Results

In general, high similarity scores were obtained. The mirror images of V₁ and V₂ are almost diametrically located on the back. Inverting these leads could render the V₈ and V₉ leads. The other mirror areas may deviate considerably from where generally expected.

Conclusion

Mirror images can be obtained consistently from all locations, supporting the dipole representation of cardiac electrical activity. Neither mirror image ECGs nor additional chest leads contribute essentially to ECG diagnosis.     

Type 1 electrocardiographic burden is increased in symptomatic patients with Brugada syndrome

Background

Spontaneous type 1 electrocardiographic (ECG) is a risk factor for arrhythmic events in Brugada patients but the importance of the proportion of time with a type 1 ECG is unknown.

Patients and Methods

Thirty-four Brugada patients (15 symptomatic) underwent a 24-hour 12-lead ECG recording. One-minute averaged waveforms displaying ST-segment elevation above 200 μV, with descending ST-segment and negative T-wave polarity on leads V₁-V₃ were considered as type 1 Brugada ECG. The burden was defined as the percentage of type 1 Brugada waveforms.

Results

Type 1 ECG on lead V2 was more frequent in symptomatic patients (median 80.6% [15.7-96.7] vs 12.4% [0.0-69.7], P = .05). Patients with a permanent type 1 pattern on lead V₂ were more likely to be symptomatic (5/6) than patients without type 1 ECG during a 24-hour period (2/9) (P < .05).

Conclusion

Type 1 pattern is more prevalent across a 24-hour period in symptomatic Brugada patients.     

The decrease in QRS amplitude after aortic valve replacement in patients with aortic valve stenosis

Purpose

The purpose of this study was to evaluate the effect of aortic valve replacement on electrocardiogram (ECG) in patients with aortic valve stenosis.

Methods

Serial 12-lead ECGs were obtained in 15 patients with aortic valve stenosis who underwent aortic valve replacement. Three ECG indexes for left ventricular hypertrophy were manually measured in each ECG: Sokolow-Lyon index (sum of S wave in V₁ and R wave in V₅), Cornell voltage index (sum of R wave in aVL and S wave in V₃), and Gubner index (sum of R wave in I and S wave in III).

Results

After aortic valve replacement, Sokolow-Lyon index gradually decreased during 2 years (51.1 ± 17.9 to 34.8 ± 12.5 mm, P < .01). Cornell voltage index (25.6 ± 7.0 to 15.0 ± 4.8 mm, P < .01) and Gubner index (15.8 ± 7.6 to 10.3 ± 5.5 mm, P < .01) also gradually decreased during 2 years. ST depression in V₆ was found in 14 patients (93%) before aortic valve replacement. It resolved in 9 of 14 patients during 2 years.

Conclusions

Electrocardiographic evidence of left ventricular hypertrophy gradually resolved after aortic valve replacement in patients with aortic valve stenosis.     

Similarity of ST and T waveforms of 12-lead electrocardiogram acquired from different monitoring electrode positions

Background

It is not always feasible to use standard electrode placement for limb leads when recording the 12-lead electrocardiogram (ECG). Other electrode placements have been accepted during monitoring. Nonstandard electrode positions, however, fail to produce waveforms identical to those recorded from the distal limb positions that are standard for diagnostic interpretation. The purpose of the present study was to validate the ST-T-segment for an alternative “Lund system” of proximal limb electrode sites.

Methods

Twelve-lead ECGs (standard, Mason-Likar, and Lund lead placement) were collected from 167 patients.

Results

There were systematic differences between measurements from standard vs Mason-Likar, but not vs the Lund system. The 95% confidence intervals of measurement agreement were similar or less when comparing measurements from the Lund system vs the first standard recording with measurements for the 2 standard recordings.

Conclusion

The Lund system might constitute a uniform convention for “diagnostic” ECGs as well as for monitoring ECG applications with regard to ST-T waveforms.     

Specific electrocardiographic markers of P-wave morphology in interatrial block

Background

Interatrial block (IAB; P waves ≥ 110 milliseconds), the conduction delay between the right (RA) and left atrium (LA), is depicted on the electrocardiogram (ECG) as prolonged, often bifid (“notched”), P waves with distinguishable RA and LA components. Although electrophysiologic (EP) studies give some insight on how RA and LA components are depicted on the surface ECG in normal conduction, few if at all any, have conclusively demonstrated this correlation with IAB. Using existing EP knowledge, we investigated if such P-wave markers on bedside ECGs exist in IAB and appraised their utility in IAB recognition.

Methods

We reviewed the medical records of patients admitted to a general hospital from December 1, 2004, to December 15, 2004. Of those, 151 patients had been admitted for nonacute presentations and were screened with 12-lead ECGs. Thirty-eight ECGs were excluded for nonsinus and paced rhythms, severe motion artifact, errors in lead placement, absence of adequate patient identification, and duplicate patient admissions after discharge. The remaining 113 ECGs were then evaluated for IAB. Sixty-three patients who did not have IAB formed the control (group A), whereas of the remaining 50 patients with IAB, 24 who had past ECGs for comparison formed group B1 and 26 without past ECGs formed group B2. Groups were compared for common clinical comorbidities, whereas sensitivity and specificity were calculated for significant P-wave markers. P values were also calculated, with a value of <.05 considered significant.

Results

Clinical characteristics of patients in all groups were statistically comparable. Overall, almost all P waves in patients with IAB (groups 1 and 2) appeared “notched” (94%, P < .0001; sensitivity, 75%; specificity, 94% for IAB recognition; positive predictive value, 94%). P-wave RA components were commonly depicted as “domes,” whereas their LA counterparts formed “spikes” (48%, P < .0001; sensitivity 96%; specificity, 70% for IAB recognition). When groups B1 and B2 were compared with increased accuracy, more P waves in group B1 were noted to have notches and had easily discernible RA and LA components; often, the RA duration is longer than the LA duration. In addition, more “dome-and-spike” complexes could be determined when past ECGs were present for comparison. These markers could be found on any bedside ECG lead in IAB but were predominant on leads II and V3 to V6.

Conclusions

Specific noninvasive surface markers such as P-wave “dome-and-spike” complexes and “notches” in any lead (predominantly leads II and V3-V6) on the bedside ECG could alert clinicians to measure P waves and so identify IAB.     

Changes in the amplitude of electrocardiogram QRS complexes during follow-up of heart failure patients

Introduction

Changes in the electrocardiogram QRS amplitudes (ECGΔ) during follow-up of heart failure (HF) patients have not been clinically exploited heretofore.

Methods

We examined ECGΔ during follow-up of HF patients by employing 42 triplets of ECGs, other laboratory and HF-related clinical data corresponding to clinical stability, worsening, and recovery from 37 HF patients.

Results

The % changes (Δ%) in the summed QRS amplitude of all 12 leads (ΣQRS_12L), 6 precordial leads (ΣQRS_V1-V6), 6 limb leads (ΣQRS_6L), leads I+II (ΣQRS_{I + II}), and lead aVR were evaluated. Also relationships between the ECG variables and body weight (BW), percent body-fat, and B-type natriuretic peptide (BNP) were examined. The QRS amplitude(s) in all ECG variables decreased from clinical stability to worsening HF, and returned to baseline at recovery. During HF worsening, Δ% was highest in lead aVR (−15.3 ± 12.3%), followed by Δ% in ΣQRS_6L (−12.9 ± 10.1%) and ΣQRS_{I + II} (−12.1 ± 10.8%). At worsening HF and its recovery, Δ% in ΣQRS_6L correlated with Δ% in percent body-fat (r = 0.333, P = .031; r = 0.308, P = .047). At recovery, Δ% in each ECG variable correlated with Δ% in BW. Receiver operating characteristic (ROC) analysis showed that ≥16% reduction of ΣQRS_6L and ΣQRS_{I + II} discriminated between stable and worsening HF, with a sensitivity of 43% and 40%, and specificity of 98% for both. ECG variables from limb lead(s) had as good area under the curve (AUC) (0.78-0.84) as BNP (AUC: 0.88) for identifying worsening HF.

Conclusions

Changes of the QRS amplitudes in ECGs are as useful for monitoring HF patients as BNP.     

P-wave amplitude and pulmonary artery pressure in scleroderma

Background and Purpose

Scleroderma is an immune-mediated disease characterized by excess deposition of collagen leading to microvascular occlusion. Morbidity and mortality are often secondary to pulmonary hypertension from injury to pulmonary microvasculature and interstitial lung disease. This study correlated P-wave findings on the 12-lead electrocardiogram (ECG) with mean pulmonary artery pressure (mPAP) measured by right heart catheterization in patients with scleroderma.

Methods

A retrospective review of 12-lead ECGs in 23 patients referred to a rheumatology clinic with the diagnosis of scleroderma was performed. Right heart catheterization was performed within 1 month of the resting ECG.

Results

Linear regression related P-wave amplitude in lead II with mPAP (r = 0.52, P = .011) This model was 73% sensitive and 67% specific for the presence or absence of elevated mPAP.

Conclusions

P-wave amplitude analysis on the ECG may be helpful in the assessment of pulmonary hypertension in patients with scleroderma.