Validation of improved vessel-specific leads (VSLs) for detecting acute myocardial ischemia.

BACKGROUND: Existing criteria recommended by ACC/ESC for identifying patients with ST elevation myocardial infarction (STEMI) from the 12-lead ECG perform with high specificity (SP), but low sensitivity (SE). In our previous studies, we found that the SE of ischemia detection can be markedly improved without any loss of SP by calculating, from the 12-lead ECG, ST deviation in 3 "optimal" vessel-specific leads (VSLs). Our original VSLs, based on ΔST body-surface potential maps (BSPMs), have been modified by using the more appropriate J-point BSPMs at peak ischemia (without subtraction of pre-occlusion distributions). The aim of the present study was to compare the performance of these new VSLs with that achieved by the STEMI criteria used in current practice. METHODS: Two independent datasets of 12-lead ECGs were used: the STAFF III dataset acquired during ischemic episodes caused by balloon inflation in LAD (n=35), RCA (n=47), and LCx (n=17) coronary arteries, and the Glasgow dataset comprising admission 12-lead ECGs of 116 patients who were hospitalized for chest pain and underwent contrast-enhanced cardiac MRI that confirmed AMI in 58 patients (50%). RESULTS: We found that, in the STAFF III dataset, the detection of ischemic state by the STEMI criteria attained SE/SP of 60/97%, whereas SE/SP values of VSLs were 72/98%. In the Glasgow dataset, STEMI criteria yielded SE/SP of 43/98%, whereas the VSLs improved SE/SP to 60/98%. The most significant increase in diagnostic performance appeared in patients with LCx coronary artery occlusion: in STAFF III data (n=17) SE achieved by STEMI criteria was improved by the VSLs from 35% to 71%; in Glasgow data (n=12) SE of 31% achieved by STEMI criteria was improved by the VSLs to 69%. CONCLUSION: In our study population, existing ACC/ESC STEMI criteria complemented by the new VSLs yielded much improved sensitivity of ischemia detection without any detrimental effect on specificity. This finding needs to be corroborated on a larger chest-pain patient population with typical prevalence of acute ischemia presented to the emergency rooms.

Monocyte chemoattractant protein-1: a dichotomous role in cardiac remodeling following acute myocardial infarction in man?

INTRODUCTION: Monocyte chemoattractant protein-1 (MCP-1) is elevated after acute myocardial infarction (AMI), and potentiates left ventricular (LV) remodeling in murine models of AMI. We examined the relationships between serum MCP-1, change in LV function and biomarkers related to remodeling in a cohort of AMI patients. METHODS: Serum MCP-1 concentrations were measured in 100 patients (age 58.9+/-12.0 years, 77% male) admitted with AMI and LV dysfunction, at baseline (mean 46 h), 12 and 24 weeks; cardiac magnetic resonance imaging and measurement of matrix metalloproteinase-2 (MMP-2), MMP-3 and MMP-9 occurred at each time-point. RESULTS: MCP-1 increased significantly from 697 [483, 997]pg/mL at baseline to 878 [678, 1130]pg/mL at 24 weeks (p<0.001). MMP-3 concentration increased while MMP-9 decreased significantly over time; MMP-2 concentration did not change significantly. BASELINE MCP-1 correlated with change in (Delta) LV end-systolic volume index (DeltaLVESVI; r= -0.48, p=0.01) and with DeltaLV ejection fraction (DeltaLVEF; r=0.50, p=0.02). However, DeltaMCP-1 correlated positively with DeltaLVESVI (r=0.40, p=0.006) and negatively with DeltaLVEF (r= -0.36, p=0.004). MCP-1 had no relationship with any MMP. CONCLUSIONS: MCP-1 may have a dichotomous role following AMI, aiding early infarct healing but potentiating later remodeling, which merits further study before any therapeutic trials of MCP-1 modulation in humans.

Microvascular obstruction remains a portent of adverse remodeling in optimally treated patients with left ventricular systolic dysfunction after acute myocardial infarction.

BACKGROUND: Microvascular obstruction (MO) is associated with large acute myocardial infarction and lower left ventricular (LV) ejection fraction and predicts greater remodeling, but whether this effect is abolished by contemporary antiremodeling therapies is subject to debate. We examined the influence of several infarct characteristics, including MO, on LV remodeling in an optimally treated post-acute myocardial infarction cohort, using contrast-enhanced cardiac magnetic resonance. METHODS AND RESULTS: One hundred patients (mean age, 58.9+/-12 years, 77%men) underwent contrast-enhanced cardiac magnetic resonance at baseline (approximately 4 days) and at 12 and 24 weeks. The effects on LV remodeling (ie, change in LV end-systolic volume index [DeltaLVESVi]) of infarct site, transmurality, endocardial extent, and the presence of early and late MO were analyzed. Mean baseline infarct volume index decreased from 34.0 (21.2) mL/m(2) to 20.9 (12.9) mL/m(2) at 24 weeks (P<0.001). Infarct site had no influence on remodeling, but greater baseline infarct transmurality (r=0.47, P<0.001) and endocardial extent (r=0.26, P<0.01) were associated with higher DeltaLVESVi. Early MO was seen in 69 patients (69%) and persisted as late MO in 56 patients (56%). Patients with late MO underwent significantly greater remodeling than those without MO (DeltaLVESVi, +4.1 [13.4] versus -7.0 [12.7] mL/m(2), respectively, P=0.001); those with early MO only displayed an intermediate DeltaLVESVi (-4.9 [13.0] mL/m(2)). Importantly, late MO was seen frequently despite optimal coronary blood flow having been restored at angiography. CONCLUSIONS: Late MO on predischarge contrast-enhanced cardiac magnetic resonance remains an ominous predictor of adverse LV remodeling despite powerful antiremodeling therapy and may be useful in the risk stratification of survivors of acute myocardial infarction.

Comparison of serial measurements of infarct size and left ventricular ejection fraction by contrast-enhanced cardiac magnetic resonance imaging and electrocardiographic QRS scoring in reperfused anterior ST-elevation myocardial infarction.

BACKGROUND: Left ventricular ejection fraction (LVEF) is a powerful prognostic marker after acute myocardial infarction and is dependent on infarct magnitude. Contrast-enhanced cardiac magnetic resonance (ceCMR) represents the current criterion standard means of LVEF and infarct size measurement. Infarct size and LVEF can be estimated from the 12-lead electrocardiogram (ECG) using the Selvester QRS score. We examined for the first time the relationship between serial measures of LVEF and infarct size by ceCMR and ECG in patients with reperfused anterior ST-elevation myocardial infarction (STEMI) and depressed LVEF. METHODS: Thirty-four patients (mean +/- SD age, 59 +/- 11.8 years; 70.6% male) underwent ceCMR and simultaneous ECG at mean 93 hours after admission and at 12 and 24 weeks. The QRS score was calculated on each ECG, from which infarct size and LVEF were estimated and compared with the equivalent ceCMR measurements. RESULTS: Infarct size on ceCMR was higher than that by QRS score at each time-point (P < .001) with modest correlation (r = 0.56-0.78, P < .001). Left ventricular ejection fraction was consistently significantly higher on CMR than on ECG, with weak correlation (r = 0.37-0.51, P < .05). We derived a novel equation relating QRS score to CMR-measured LVEF in the subacute phase of infarction: LVEF = 61 - (1.7 x QRS score) (%). CONCLUSIONS: In patients with reperfused anterior ST-elevation myocardial infarction and depressed LVEF, ceCMR is moderately correlated with the QRS in the serial measurement of infarct size and LVEF. Infarct size (measured by ceCMR) and LVEF are consistently higher than those calculated on the QRS score in the acute and subacute phases of infarction.

Comparison of the correlation of the Selvester QRS scoring system with cardiac contrast-enhanced magnetic resonance imaging-measured acute myocardial infarct size in patients with and without thrombolytic therapy.

BACKGROUND: After an acute myocardial infarction (MI), it is important to define the infarct size because it is related to mortality and morbidity. The Selvester QRS Score is an electrocardiographic (ECG) method that has been developed for estimating MI size. It has been shown to correlate well with postmortem anatomically measured sizes of single MI in patients who did not receive thrombolytic therapy. The aim of this study was to test the hypothesis that correlation between Selvester QRS Score-estimated MI size and contrast-enhanced magnetic resonance imaging (ceMRI)-measured MI size is equivalent in patients who did vs those who did not receive thrombolytic therapy. METHODS: Thirty-six patients with MI (24 with thrombolytic therapy and 12 without) received ceMRI and ECG at admission and at 1 or 6 months after admission. Indeed, in 23 of the patients, the therapy was intravenous only. The Selvester QRS Score was calculated using the 1-month ECG or, if not available, the 6-month ECG. The correlation between the 2 measures of MI size was determined for all patients and for the 2 groups separately. RESULTS: The mean MI size in the group that did not receive thrombolytic therapy was 8.5% +/- 6.4% estimated by the Selvester QRS Score and 11.7% +/- 10.2% measured by ceMRI. For the group that received thrombolytic therapy, Selvester QRS Score was 13.9% +/- 11.1% and ceMRI was 20.2% +/- 11.3%. The mean MI size in both groups combined was 12.1% +/- 10.0% estimated by the Selvester QRS Score and 17.3% +/- 11.5% measured by ceMRI. The Spearman rank correlation coefficient between Selvester QRS Score and ceMRI was 0.74 (P < .0001) for all patients, 0.74 (P < .0001) for the group that received thrombolytic therapy, and 0.64 (P = .024) for the group that did not receive thrombolytic therapy. CONCLUSIONS: The associations between Selvester QRS Score and ceMRI-based MI were statistically significant and similar in both groups.

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.

Cardiac and extracardiac abnormalities detected by cardiac magnetic resonance in a post-myocardial infarction cohort.

OBJECTIVES: All patients should undergo formal assessment of ventricular function following acute myocardial infarction (AMI). Cardiac magnetic resonance (CMR) is not widely used as a test before discharge in AMI patients. This study sought to determine the impact of contrast-enhanced CMR (ceCMR) scanning before discharge in addition to standard transthoracic echocardiography (TTE) on patient care following AMI. METHODS: 100 patients admitted with AMI, all of whom had a left ventricular ejection fraction (LVEF) <40% on TTE, underwent ceCMR imaging before discharge. Abnormalities of clinical relevance detected on ceCMR, which influenced patient management, are reported. RESULTS: Each patient (77% male, mean age 58.9 years, SD 12) underwent TTE and ceCMR at a mean 1.4 (range 0.8-3.2) and 4.2 days (range 2-11), respectively, following admission. ceCMR significantly influenced the management of 24/100 (24%) of the patient cohort, through detection of LV thrombus, right ventricular infarction, intracardiac neoplasia, and a variety of intrathoracic and intra-abdominal pathology. There were no issues regarding safety in this high-risk group of patients. CONCLUSION: In a cohort of AMI patients with reduced LVEF, ceCMR scanning before discharge improved the management of 24% of the cohort. ceCMR is a useful and safe adjunct to standard care after AMI.

ST-segment deviation analysis of the admission 12-lead electrocardiogram as an aid to early diagnosis of acute myocardial infarction with a cardiac magnetic resonance imaging gold standard.

OBJECTIVES: The purpose of this study was to validate existing 12-lead electrocardiographic (ECG) ST-segment elevation myocardial infarction (STEMI) criteria in the diagnosis of acute myocardial infarction (AMI) and the application of similar ST-segment depression (STEMI-equivalent) criteria with contrast-enhanced cardiac magnetic resonance imaging (ceMRI) as the diagnostic gold standard. BACKGROUND: The admission ECG is the cornerstone in the diagnosis of AMI, and ceMRI is a new diagnostic gold standard that can be used to validate existing and novel 12-lead ECG criteria. METHODS: One hundred fifty-one consecutive patients with their first hospital admission for chest pain underwent ceMRI. The 116 patients without ECG confounding factors were included in this study, and AMI was confirmed in 58 (50%). The admission ECG was evaluated on the basis of the lead distribution of ST-segment deviation according to current American College of Cardiology/European Society of Cardiology (ACC/ESC) guidelines. RESULTS: A sensitivity of 50% and specificity of 97% for AMI were achieved with the currently applied ST-segment elevation criteria. Consideration of ST-segment depression in addition to elevation increased sensitivity for detection of AMI from 50% to 84% (p < 0.0001) but only decreased specificity from 97% to 93% (p = 0.50). There were no significant differences in AMI location or size between patients meeting the 12-lead ACC/ESC ST-segment elevation criteria and those only meeting the ST-segment depression criteria. CONCLUSIONS: In patients admitted to hospital with possible AMI, the consideration of both ST-segment elevation and depression in the standard 12 lead-ECG recording significantly increases the sensitivity for the detection of AMI with only a slight decrease in the specificity.

The relationship between electrical axis by 12-lead electrocardiogram and anatomical axis of the heart by cardiac magnetic resonance in healthy subjects.

BACKGROUND: The traditional assumption has been that there is a close relationship between the electrical and anatomical axes of the heart. The aim of this study was to test the hypothesis that there is a correlation between the electrical and anatomical axes of the heart, in both the frontal and transverse planes, in healthy subjects. METHODS: Ninety-four healthy volunteers (48 men, 46 women; age 21-82 years) were studied by cardiac magnetic resonance and 12-lead electrocardiogram. The anatomical axis was determined by cardiac magnetic resonance and projected onto the frontal and transverse orthogonal planes for comparison with the electrical axis in the corresponding planes. RESULTS: The electrical and anatomical axes were in the same range in the frontal plane (mean +/- SD, +39 degrees +/- 31 degrees and +38 degrees +/- 10 degrees), but in different ranges in the transverse plane (mean +/- SD, -30 degrees +/- 18 degrees and +46 degrees +/- 7 degrees). The partial correlation coefficients between electrical and anatomical axes were r = 0.30 (P < .01) and r = 0.14 (P = NS) in the frontal and transverse planes, respectively. Age was more strongly correlated to electrical axis than to anatomical axis in the frontal plane. CONCLUSIONS: There is only a weak correlation between electrical and anatomical axes in the frontal plane and no correlation in the transverse plane. The change of electrical axis with increased age is not explained only by change in the anatomical axis. The results suggest that there is no simple relationship between the electrical and anatomical axes of the heart.

Determination of left ventricular long-axis orientation using MRI: changes during the respiratory and cardiac cycles in normal and diseased subjects.

BACKGROUND: It has previously been shown that magnetic resonance imaging (MRI) can be used to accurately determine left ventricular (LV) long-axis orientation in healthy individuals. However, the inter- and intra-observer variability in patients with acute coronary syndrome (ACS) and chronic heart failure (CHF) has not been explored. Furthermore, the changes in LV long-axis orientation because of respiration and during the cardiac cycle remain to be determined. METHODS: LV long-axis orientation was determined by MRI in the frontal and transverse planes in 44 subjects with no cardiac disease, 20 ACS patients and 13 CHF patients. Changes in LV long-axis orientation because of respiration were assessed in a subset of 25 subjects. Changes during the cardiac cycle were assessed in six subjects from each subject group. Reproducibility was assessed by a re-examination of 17 subjects after 28 days. RESULTS: The inter- and intra-observer variability for LV long-axis orientation was low for all subject groups. The difference between the baseline and the 28 days examinations was -1.4+/-5.9 degrees and -0.8+/-4.4 degrees in the frontal and transverse planes, respectively. No significant change in LV long-axis orientation was found between end-expiration and end-inspiration (frontal plane, P=0.63 and transverse plane, P=0.42; n=25). No significant difference in change of the LV long-axis orientation during the cardiac cycle was found between the subject groups (frontal plane, chi-square 1.8, P=0.40 and transverse plane, chi-square 5.7, P=0.06). CONCLUSIONS: There is a low inter-and intra-observer variability and a high reproducibility for determining LV long-axis orientation in patients with no cardiac disease as well as in patients with ACS or CHF. There is no significant change in LV long-axis orientation due to respiration, and only small changes during the cardiac cycle in these groups.

Contrast enhanced-cardiovascular magnetic resonance imaging in patients with pulmonary hypertension.

AIMS: To determine the presence and extent of delayed contrast enhancement (DCE) in patients with pulmonary hypertension (PHT) using contrast enhanced-cardiovascular magnetic resonance imaging (ce-CMR). METHODS AND RESULTS: Twenty-five patients with PHT underwent ce-CMR and right heart catheterization. Right ventricular (RV) and left ventricular (LV) volumes, ejection fraction, mass, and DCE mass were determined with ce-CMR. Mean pulmonary artery pressure (mean PAP) averaged 43 (12) mmHg and cardiac output 4.3 (1.2) L/min. DCE was demonstrated in 23 out of 25 patients. DCE was confined to the RV insertion points (RVIPs) in seven patients and extended into the interventricular septum (IVS) in the remaining 16 patients. In these 16 patients, septal contrast enhancement was associated with IVS bowing. The extent of contrast enhancement correlated positively with RV end-diastolic volume/body surface area, RV mass, mean PAP, and pulmonary vascular resistance and correlated inversely with RV ejection fraction. CONCLUSION: DCE was present within the RVIPs and IVS of most patients with PHT studied. Extent of DCE correlated with RV function and pulmonary haemodynamics. DCE was associated with IVS bowing and may provide a novel marker for occult septal abnormalities directly relating to the haemodynamic stress experienced by these patients.

Matrix metalloproteinase-1 promoter polymorphisms and changes in left ventricular volume following acute myocardial infarction.

The relation between matrix metalloproteinase-1 promoter genotype and remodeling was studied in 42 patients after their first acute myocardial infarctions. Patients possessing 2 GG alleles were at increased risk for remodeling compared with homozygotes for the G allele and heterozygotes possessing 1 G and 1 GG allele.