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AimsDormant coronary collaterals are highly prevalent and clinically beneficial in cases of coronary occlusion. However, the magnitude of myocardial perfusion provided by immediate coronary collateral recruitment during acute occlusion is unknown. The aim of this study was to quantify collateral myocardial perfusion during balloon occlusion in patients with coronary artery disease (CAD).Methods and resultsPatients without angiographically visible collaterals undergoing elective percutaneous transluminal coronary angioplasty (PTCA) to a single epicardial vessel underwent two scans with 99mTc-sestamibi myocardial perfusion single-photon emission computed tomography (SPECT). All subjects underwent at least three minutes of angiographically verified complete balloon occlusion, at which time an intravenous injection of the radiotracer was administered, followed by SPECT imaging. A second radiotracer injection followed by SPECT imaging was performed 24 hours after PTCA.The study included 22 patients (median [interquartile range] age 68 [54-72] years, 10 (45%) female). The perfusion defect extent was 19 [11–38] % of the LV, and the collateral perfusion at rest was 64 [58-67]% of normal.ConclusionThis is the first study to describe the magnitude of short-term changes in coronary microvascular collateral perfusion in patients with CAD. On average, despite coronary occlusion and an absence of angiographically visible collateral vessels, collaterals provided more than half of the normal perfusion.Graphical abstractDormant collaterals are highly prevalent but the magnitude of myocardial perfusion provided by immediate coronary collateral recruitment during acute occlusion in humans is unknown. Patients without angiographically visible collaterals underwent intravenous injection with 99mTc-sestamibi during coronary balloon inflation followed by SPECT imaging. A control scan was performed 24 hours later..Median collateral perfusion during coronary occlusion was 64% of normal.

Introduction Studies have shown terminal QRS distortion and resultant QRS prolongation during ischemia to be a sign of low cardiac protection and thus a faster rate of myocardial cell death. A recent study introduced a single lead method to quantify the severity of ischemia by estimating QRS prolongation. This paper introduces a 12-lead method that, in contrast to the previous method, does not require access to a prior ECG. Methods QRS duration was estimated in the lead that showed the maximal ST deviation according to a novel method. The degree of prolongation was determined by subtracting the measured QRS duration in the lead that showed the least ST deviation. Results The method is demonstrated in examples of acute occlusion in two of the major coronary arteries. Conclusion This paper presents a 12-lead method to quantify the severity of ischemia, by measuring QRS prolongation, without requiring comparison with a previous ECG.

Aims Catheter ablation is considered the treatment of choice for many tachyarrhythmias, but convincing real-world data on efficacy and safety are lacking. Using Swedish national registry data, the ablation spectrum, procedural characteristics, as well as ablation efficacy and reported adverse events are reported. Methods and Results Consecutive patients (18years of age) undergoing catheter ablation in Sweden between 01 January 2006 and 31 December 2015 were included in the study. Follow-up (repeat ablation and vital status) was collected through 31 December 2016. A total of 26642 patients (5715years, 62% men), undergoing a total of 34428 ablation procedures were included in the study. In total, 4034 accessory pathway/Wolff-Parkinson-White syndrome (12%), 7358 AV-nodal re-entrant tachycardia (21%), 1813 atrial tachycardia (5.2%), 5481 typical atrial flutter (16%), 11916 atrial fibrillation (AF, 35%), 2415 AV-nodal (7.0%), 581 premature ventricular contraction (PVC, 1.7%), and 964 ventricular tachycardia (VT) ablations (2.8%) were performed. Median follow-up time was 4.7years (interquartile range 2.7-7.0). The spectrum of treated arrhythmias changed over time, with a gradual increase in AF, VT, and PVC ablation (Pamp;lt;0.001). Decreasing procedural times and utilization of fluoroscopy with time, were seen for all arrhythmia types. The rates of repeat ablation differed between ablation types, with the highest repeat ablation seen in AF (41% within 3years). The rate of reported adverse events was low (n=595, 1.7%). Death in the immediate period following ablation was rare (n=116, 0.34%). Conclusion Catheter ablations have shifted towards more complex procedures over the past decade. Fluoroscopy time has markedly decreased and the efficacy of catheter ablation seems to improve for AF. Funding Agencies|Swedish Association of Local Authorities and Regions; Crafoord Foundation; Eva and Carl-Eric Larsson Foundation; Bundy Academy; Skane University Hospital Research Foundation; Swedish Heart-Lung Foundation

BACKGROUND: Patients with acute coronary occlusion (ACO) may not only have ischemia‐related ST‐segment changes but also changes in the QRS complex. It has recently been shown in dogs that a greater ischemic QRS prolongation (IQP) during ACO is related to lower collateral flow. This suggests that greater IQP could indicate more severe ischemia and thereby more rapid infarct development. Therefore, the purpose was to evaluate the relationship between IQP and measures of myocardial injury in patients presenting with acute ST‐elevation myocardial infarction (STEMI). METHODS: Seventy‐seven patients with first‐time STEMI were retrospectively included from the recently published SOCCER trial. All patients underwent a cardiac magnetic resonance (CMR) examination 2–6 days after the acute event. Infarct size (IS), myocardium at risk (MaR), and myocardial salvage index (MSI) were assessed and related to IQP. IQP measures assessed were; computer‐generated QRS duration, QRS duration at maximum ST deviation, absolute IQP and relative IQP, all derived from a pre‐PCI, 12‐lead ECG. RESULTS: Median absolute IQP was 10 ms (range 0–115 ms). There were no statistically significant correlations between measures of IQP and any of the CMR measures of myocardial injury (absolute IQP vs IS, r = 0.03, p = 0.80; MaR, r = −0.01, p = 0.89; MSI, r = −0.05, p = 0.68). CONCLUSIONS: Unlike previous experimental studies, the IQP was limited in patients presenting at the emergency room with first‐time STEMI and no correlation was found between IQP and CMR variables of myocardial injury in these patients. Therefore, IQP does not seem to be a suitable biomarker for triaging patients in this clinical context.

OBJECTIVES. An acute coronary occlusion and its possible subsequent complications is one of the most common causes of death. One such complication is ventricular fibrillation (VF) due to myocardial ischemia. The severity of ischemia is related to the amount of coronary arterial collateral flow. In dog studies collateral flow has also been shown to be associated with QRS prolongation. The aim of this study was to investigate whether ischemic QRS prolongation (IQP) is associated with impending VF in an experimental acute ischemia dog model. METHODS. Degree of IQP and occurrence of VF were measured in dogs (n=21) during coronary occlusion for 15 minutes and also during subsequent reperfusion (experiments conducted in 1984). RESULTS. There was a significant difference in absolute IQP between dogs which developed VF during reperfusion (47 ±29 ms, mean ±SD) and those which did not (12 ±10 ms; p=0.001). CONCLUSIONS. IQP during acute coronary occlusion is associated with reperfusion VF in an experimental dog model and might therefore be a potential predictor of malignant arrhythmias in patients with acute coronary syndrome.

The STAFF III database was acquired with the aim of better understanding the ECG signatures observed during acute ischemia, with special focus on high-frequency QRS components. The database contains recordings from 104 patients undergoing elective balloon percutaneous coronary intervention. The database has not only been analyzed in numerous clinical studies, but also turned out to be an excellent tool for methodological development. Its use has, by far, exceeded the original aim. Inspired by this fact, the database has now been made publicly available at Physionet.

BACKGROUND: In STEMI, grade-3 ischemia (G3) on admission ECG predicts larger infarct size (IS) than grade-2 (G2). We evaluated whether pre-hospital G3 and its temporal behavior are associated with IS and salvage after pPCI.METHODS: In 401 STEMI patients, pre-hospital and pre-PCI ECGs were classified as G3 or G2. IS was assessed by single-photon emission computed tomography (SPECT) at 30days. In 245 patients, pre-PCI SPECT was available to determine myocardium at risk (MaR).RESULTS: G3 criteria were met by 88, and G2 by 313 patients. G3 was independently associated with IS (p=0.006). With ST resolution (STR) group as a reference, G2->G2, G2->G3 and G3->G3 were associated with larger IS (B=4.4, p=0.004; B=5.4, p=0.01; B=10.2, pG2 was not. Salvage was similar between G3 and G2 on pre-hospital ECG if treated early, however lower for G3 when treated later (>2.5h); 48% (35-78) vs 62% (40-87); p=0.04.CONCLUSION: Development or persistence of G3 is associated with larger IS and less salvage, but decreasing grade G3->G2 was not.

Ischemic preconditioning is a form of intrinsic cardioprotection where an episode of sublethal ischemia protects against subsequent episodes of ischemia. Identifying a clinical biomarker of preconditioning could have important clinical implications, and prior work has focused on the electrocardiographic ST segment. However, the electrophysiology biomarker of preconditioning is increased action potential duration (APD) shortening with subsequent ischemic episodes, and APD shortening should primarily alter the T wave, not the ST segment. We translated findings from simulations to canine to patient models of preconditioning to test the hypothesis that the combination of increased [delta (Δ)] T wave amplitude with decreased ST segment elevation characterizes preconditioning. In simulations, decreased APD caused increased T wave amplitude with minimal ST segment elevation. In contrast, decreased action potential amplitude increased ST segment elevation significantly. In a canine model of preconditioning (9 mongrel dogs undergoing 4 ischemia-reperfusion episodes), ST segment amplitude increased more than T wave amplitude during the first ischemic episode [ΔT/ΔST slope = 0.81, 95% confidence interval (CI) 0.46–1.15]; however, during subsequent ischemic episodes the T wave increased significantly more than the ST segment (ΔT/ΔST slope = 2.43, CI 2.07–2.80) ( P < 0.001 for interaction of occlusions 2 vs. 1). A similar result was observed in patients (9 patients undergoing 2 consecutive prolonged occlusions during elective percutaneous coronary intervention), with an increase in slope of ΔT/ΔST of 0.13 (CI −0.15 to 0.42) in the first occlusion to 1.02 (CI 0.31–1.73) in the second occlusion ( P = 0.02). This integrated analysis of the T wave and ST segment goes beyond the standard approach to only analyze ST elevation, and detects cellular electrophysiology changes of preconditioning.

Background Previous studies have shown that QRS prolongation is a sign of depressed collateral flow and increased rate of myocardial cell death during coronary occlusion. The aims of this study were to evaluate ischemic QRS prolongation as a biomarker of severe ischemia by establishing the relationship between prolongation and collateral flow experimentally in a dog model, and test if the same pattern of ischemic QRS prolongation occurs in man. Methods Degree of ischemic QRS prolongation was measured using a novel method in dogs (n = 23) and patients (n = 52) during coronary occlusion for 5 min. Collateral arterial flow was assessed in the dogs. Results There was a significant correlation between QRS prolongation and collateral flow in dogs (r = 0.61, p = 0.008). Magnitude and temporal evolution of prolongation during ischemia were similar for dogs and humans (p = 0.202 and p = 0.911). Conclusion Quantification of ischemic QRS prolongation could potentially be used as a biomarker for severe myocardial ischemia.

Diagnosis and risk stratification of patients with acute coronary syndromes can be improved by adding information from the depolarization phase (QRS complex) to the conventionally used ST-T segment changes. In this study, ischemia-induced changes in the main three slopes of the QRS complex, upward ( ℑ(US)) and downward ( ℑ(DS) ) slopes of the R wave as well as the upward ( ℑ(TS)) slope of the terminal S wave, were evaluated as to represent a robust measure of pathological changes within the depolarization phase. From ECG recordings both in a resting state (control recordings) and during percutaneous coronary intervention (PCI)-induced transmural ischemia, we developed a method for quantification of ℑ(US), ℑ(DS), and ℑ(TS) that incorporates dynamic ECG normalization so as to improve the sensitivity in the detection of ischemia-induced changes. The same method was also applied on leads obtained by projection of QRS loops onto their dominant directions. We show that ℑ(US), ℑ(DS), and ℑ(TS) present high stability in the resting state, thus providing a stable reference for ischemia characterization. Maximum relative factors of change ( ℜ(ℑ)) during PCI were found in leads derived from the QRS loop, reaching 10.5 and 13.7 times their normal variations in the control for ℑ(US) and ℑ(DS), respectively. For standard leads, the relative factors of change were 6.01 and 9.31. The ℑ(TS) index presented a similar behavior to that of ℑ(DS). The timing for the occurrence of significant changes in ℑ(US) and ℑ(DS) varied with lead, ranging from 30 s to 2 min after initiation of coronary occlusion. In the present ischemia model, relative ℑ(DS) changes were smaller than ST changes in most leads, however with only modest correlation between the two indices, suggesting they present different information about the ischemic process. We conclude that QRS slopes offer a robust tool for evaluating depolarization changes during myocardial ischemia.

OBJECTIVES This study describes changes in high-frequency QRS components (HF-QRS) during percutaneous transluminal coronary angioplasty (PTCA) and compares the ability of these changes in HF-QRS and ST-segment deviation in the standard 12-lead electrocardiogram (ECG) to detect acute coronary artery occlusion. BACKGROUND Previous studies have shown decreased HF-QRS in the frequency range of 150–250 Hz during acute myocardial ischemia. It would be important to know whether the high-frequency analysis could add information to that available from the ST segments in the standard ECG. METHODS The study population consisted of 52 patients undergoing prolonged balloon occlusion during PTCA. Signal-averaged electrocardiograms (SAECG) were recorded prior to and during the balloon inflation. The HF-QRS were determined within a bandwidth of 150–250 Hz in the preinflation and inflation SAECGs. The ST-segment deviation during inflation was determined in the standard frequency range. RESULTS The sensitivity for detecting acute coronary artery occlusion was 88% using the high-frequency method. In 71% of the patients there was ST elevation during inflation. If both ST elevation and depression were considered, the sensitivity was 79%. The sensitivity was significantly higher using the high-frequency method, p < 0.002, compared with the assessment of ST elevation. CONCLUSIONS Acute coronary artery occlusion is detected with higher sensitivity using high-frequency QRS analysis compared with conventional assessment of ST segments. This result suggests that analysis of HF-QRS could provide an adjunctive tool with high sensitivity for detecting acute myocardial ischemia.

In patients with ST-elevation myocardial infarction (STEMI) the amount of myocardial area at risk (MaR) indicates the maximal potential loss of myocardium if the coronary artery remains occluded. During the time course of infarct evolution ischemic MaR is replaced by necrosis, which results in a decrease in ST segment elevation and QRS complex distortion. Recently it has been shown that combining the electrocardiographic (ECG) Aldrich ST and Selvester QRS scores result in a more accurate estimate of MaR than using either method alone. Therefore, we hypothesized that the combined Aldrich and Selvester score, indicating MaR, is stable until myocardial reperfusion therapy. In a retrospective analysis of a study population of 114 patients, 33 patients were included. The combined Aldrich and Selvester score was determined in ECGs recorded in the ambulance (ECG1) and in the hospital before reperfusion (ECG2). The combined Aldrich and Selvester score was considered stable if the difference between ECG1 and ECG2 was

Background: The ECG is important in the diagnosis and triage of the acute coronary syndrome (ACS), especially in the hyperacute phase, the "golden hours," during which myocardial salvage possibilities are largest. An important triaging decision to be taken is whether or not a patient requires primary PCI, for which, as mentioned in the guidelines, the presence of an ST elevation (STE) pattern in the ECG is a major criterion. However, preexisting non-zero ST amplitudes (diagnostic, but also non-diagnostic) can obscure or even preclude this diagnosis. Methods: In this study, we investigated the potential diagnostic possibilities of ischemia detection by means of changes in the ST vector, Delta ST, and changes in the VG (QRST integral) vector, Delta VG. We studied the vectorcardiograms (VCGs) synthesized of the ECGs of 84 patients who underwent elective PTCA. Mean +/- SD balloon occlusion times were 260 +/- 76 s. The ECG ischemia diagnosis (ST elevation, STE, or non-ST-elevation, NSTE), magnitudes and orientations of the ST and VG vectors, and the differences Delta ST and Delta VG with the baseline ECG were measured after 3 min of balloon occlusion. Results: Planar angles between the Delta ST and Delta VG vectors were 14.9 +/- 14.0 degrees. Linear regression of Delta VG on Delta ST yielded Delta VG = 324. Delta ST (r = 0.85; P 0.05 mV, and the corresponding Delta VG > 16.2 mV.ms as ischemia thresholds. The classical criteria characterized the ECGs of 46/84 (55%) patients after 3 min of occlusion as STE ECGs. Combined application of the Delta ST and Delta VG criteria identified 73/84 (87%) of the patients as ischemic. Conclusion: Differential diagnosis by Delta ST and Delta VG (requiring an earlier made non-ischemic baseline ECG) could dramatically improve ECG guided detection of patients who urgently require catheter intervention. (C) 2013 Elsevier Inc. All rights reserved. (Less)

In this study we evaluated the three main slopes of the QRS complex (upslope \(\mathcal{I}_{US}\) and downslope \(\mathcal{I}_{DS}\) of the R wave, and terminal slope \(\mathcal{I}_{TS}\) of the S wave) in both standard and derived ECG leads obtained from spatial QRS loops, either by the vectorcardiogram (VCG) or by principal component analysis (PCA), in 79 patients undergoing prolonged, elective percutaneous coronary intervention (PCI). For each patient, the slope indices \(\mathcal{I}_{US}\), \(\mathcal{I}_{DS}\) and \(\mathcal{I}_{TS}\) were evaluated in the PCI recording as well as in a control recording acquired before the PCI procedure, and relative factors of change during PCI were calculated. We showed that \(\mathcal{I}_{US}\) and \(\mathcal{I}_{DS}\) computed over VCG and PCA leads present higher sensitivity to the ischemiainduced changes than the same indices evaluated over the standard 12-lead ECG. The mean relative factors of change RI were 10.5 and 12.4 for \(\mathcal{I}_{US}\) and \(\mathcal{I}_{DS}\) in PCA, and 7.87 and 13.7 in VCG, respectively, representing an increase in sensitivity of up to 103% for \(\mathcal{I}_{US}\) and 46% for \(\mathcal{I}_{DS}\) compared to measurements obtained in lead V3. We conclude that evaluation of slope indices in leads derived from QRS loops significantly increases their potential value for detection of acute myocardial ischemia.

Objective: In acute myocardial ischemia changes within the QRS complex can add valuable information to that from the repolarization phase. This study evaluates three angles obtained from the main slopes of the R-wave within the QRS complex to assess acute myocardial ischemia. Methods: The QRS angles, denoted by OR (R-wave angle), OU (up-stroke angle) and OD (downstroke angle), were evaluated in 12-lead electrocardiogram (ECG) recordings of 79 patients before and during coronary occlusion by elective percutaneous coronary intervention (PCI). In a subset of 38 patients, ischemia was quantified by myocardial scintigraphy. Results: At baseline the QRS angles presented low variations. During occlusion, OU and OD developed a fast and abrupt change, whereas OR showed a smaller and gradual change. There were significant correlations between both maximal and sum of positive change in OR and ischemia: r = 0.67; p b 0.001 and r = 0.78; p b 0.001, for extent, and r = 0.60; p b 0.001 and r = 0.73; p b 0.001, for severity, respectively. Prediction of extent and severity of ischemia increased by 50% by adding OR changes to ST-segment changes, for LCX occlusions, whereas increased by 12.1% and 24.6% for LAD and RCA occlusions, respectively. No significant correlation was seen between OU and OD angles and ischemia. Conclusions: Evaluation of QRS angles from the standard 12-lead ECG represents a sensitive marker for detection of acute myocardial ischemia, whereas, OR changes can be used for prediction of its extent and severity.

In this study, several electrocardiogram (ECG)-derived indices corresponding to both ventricular depolarization and repolarization were evaluated during acute myocardial ischemia in an experimental model of myocardial infarction produced by 40 min coronary balloon inflation in 13 pigs. Significant changes were rapidly observed from minute 4 after the start of coronary occlusion, achieving their maximum values between 11 and 22 min for depolarization and between 9 and 12 min for repolarization indices, respectively. Subsequently, these maximum changes started to decrease during the latter part of the occlusion. Depolarization changes associated with the second half of the QRS complex showed a significant but inverse correlation with the myocardium at risk (MaR) estimated by scintigraphic images. The correlation between MaR and changes of the downward slope of the QRS complex, [Formula: see text], evaluated at the two more relevant peaks observed during the occlusion, was r = -0.75, p0.01 and r = -0.79, p0.01 for the positive and negative deflections observed in [Formula: see text], temporal evolution, respectively. Repolarization changes, analyzed by evaluation of ST segment elevation at the main observed positive peak, also showed negative, however non-significant correlation with MaR: r = -0.34, p = 0.28. Our results suggest that changes evaluated in the latter part of the depolarization, such as those described by [Formula: see text], which are influenced by R-wave amplitude, QRS width and ST level variations simultaneously, correlate better with the amount of ischemia than other indices evaluated in the earlier part of depolarization or during the ST segment.

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.

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 (

In clinical practice ST elevation is used in the ECG to detect myocardial infarction. Additional information from the depolarization phase (QRS complex) can improve diagnosis and risk stratification of the patient. In this paper we present a study of the upward (\(\mathcal{I}_{\rm US}\)) and downward (\(\mathcal{I}_{\rm DS}\)) slopes of the QRS complex as an alternative for detecting and quantifying ischemia induced depolarization changes. From ECG recordings both in a resting state (control recordings) and during PCI-induced transmural ischemia, we develop a method for quantification of \(\mathcal{I}_{\rm US}\) and \(\mathcal{I}_{\rm DS}\) that incorporates dynamic ECG normalization so as to improve sensitivity in the detection of ischemia induced changes. We show that \(\mathcal{I}_{\rm US}\) and \(\mathcal{I}_{\rm DS}\) present high stability at resting state, thus providing a stable reference for ischemia characterization. In PCI recordings we show that \(\mathcal{I}_{\rm US}\) and \(\mathcal{I}_{\rm DS}\) present maximum relative factors of change of 6.01 and 9.31, respectively, with respect to their own variability at control. We also show that the timing for the occurrence of significant changes in \(\mathcal{I}_{\rm US}\) and \(\mathcal{I}_{\rm DS}\) varies with lead, ranging from 30 s to 2 min after initiation of coronary occlusion. We conclude that QRS slopes offer a robust tool for evaluating depolarization changes during myocardial ischemia.

Presents some preliminary data suggesting that acute myocardial ischemia may be uniquely detectable in the QRS complex of the high resolution ECG. It is hypothesized that acute ischemia may create functional block, leading to ischemically-altered ventricular activation patterns. The study assessed four subjects undergoing elective PTCA. A continuous 12-lead HRECG was recorded and analyzed in 1-minute segments. Changes in the HRECG between the preinflation, artery-occluded and post-deflation states took the form of abnormal intra-QRS potentials. These data were trended and compared to severity estimates of ischemia obtained during balloon occlusion by tomographic scintigraphy. The abnormal QRS potentials may predict the overall degree of myocardial ischemia and exhibit forms which are specific to the artery occluded.

BACKGROUND: This study compares the high-frequency QRS components (HF-QRS) in patients with and without standard electrocardiogram (ECG) changes indicative of old myocardial infarction (MI). Previous studies have indicated that patients with an old MI differ in their HF-QRS compared with healthy subjects. The HF-QRS has been reported to be decreased during acute coronary occlusion and increased after reperfusion. However, there is controversy about the appearance of HF-QRS after the acute phase of MI. METHODS: A total of 154 patients were included, 57 with and 97 without QRS changes of old MI on the standard ECG. The patients with old MI were divided into subgroups on the basis of the MI location indicated by the standard ECG. Signal-averaged ECGs from the 12 standard leads were recorded. The root-mean-square values of the HF-QRS were determined within two frequency bands: 150 to 250 Hz and 80 to 300 Hz. RESULTS: There was a large interindividual variation in HF-QRS in patients without MI as well as in those with different MI locations. There were no significant differences between the groups in the summed HF-QRS of all 12 leads or in the pattern of lead distribution of the HF-QRS. Not even the patients with the greatest QRS changes of old MI could be differentiated from those without any changes of old MI on the standard ECG. The results were the same in both analyzed frequency bands. CONCLUSIONS: This study shows, contrary to previous studies, that analysis of HF-QRS cannot differentiate between patients with and without old MI. (Less)

BACKGROUND: Analysis of high-frequency QRS amplitudes (HF-QRS) may provide an additional diagnostic tool in patients with heart disease, but the basic properties of these waveforms have not been sufficiently investigated. This study describes the spatial, individual, and temporal variation at rest of HF-QRS recorded with the 12 standard electrocardiographic leads in patients with ischemic heart disease. METHODS AND RESULTS: Two consecutive electrocardiographic recordings from 67 patients were signal averaged and analyzed within a bandwidth of 150 to 250 Hz. The HF-QRS values were expressed as root mean square values. There was a spatial variation in HF-QRS among the 12 leads, with higher amplitudes in V(2) through V(4), II, aVF, and III. The individual variation among the patients was large for all leads. The sum of the HF-QRS for all 12 leads in each patient ranged from 20 to 75 microV (mean 36 +/- 11 microV). The mean of the temporal variation in HF-QRS for all 12 leads between the 2 recordings was only 0.10 +/- 0. 09 microV. CONCLUSIONS: Because of the large individual variation, analysis of HF-QRS is probably most applicable in monitoring situations when it is possible to track changes in a patient over time. The temporal variation in HF-QRS at rest is small, both in patients with and those without prior myocardial infarction.