Location Of Myocardial Infarction Research Articles

Topology and Random-Walk Network Representation of Cardiac Dynamics for Localization of Myocardial Infarction

While detection of acute cardiac disorders such as myocardial infarction (MI) from electrocardiogram (ECG) and vectorcardiogram (VCG) has been widely reported, identification of MI locations from these signals, pivotal for timely therapeutic and prognostic interventions, remains a standing issue. We present an approach for MI localization based on representing complex spatiotemporal patterns of cardiac dynamics as a random-walk network reconstructed from the evolution of VCG signals across a 3-D state space. Extensive tests with signals from the PTB database of the PhysioNet databank suggest that locations of MI can be determined accurately (sensitivity of ∼88% and specificity of ∼92%) from tracking certain consistently estimated invariants of this random-walk representation.

240: Significant improvement of VO2 peak, after myocardial infarction, in type 2 diabetes when glycemic level is well controlled during cardiac rehabilitation. The DARE Study

It is well known that gain in VO2 peak, after cardiac rehabilitation (CR), is associated with reduced mortality and morbidity. We have previously shown that the VO2 peak improvement in CR, after myocardial infarction (MI), is significantly lower in Type 2 diabetic (T2D) patients and that response to CR seems to be impaired by poor glycemic control. Thus, we set up a prospective multicenter study (DARE Study) in order to determine whether good glycemic control during CR may improve the gain in VO2 peak. Fifty six T2D patients referred to CR after MI were randomized in an intensive treatment group (basal-bolus insulin) or in a control group (usual treatment). Fructosamine at the end of the CR program was used to assess mean glycemic level during the CR period. For the whole diabetic population studied, mean gain in VO2 peak after CR was 2.7±2.4 ml/kg/min. Gain in VO2 Peak after CR was negatively correlated with basal (r=-0.32, p<0.05) and final fructosamine (r=-0.36, p=0.01) and with basal (r=−0.36, p<0.05) and final HbA1c (r=-0.34, p<0.05). At the end of the CR program, the gain in VO2 peak and the reduction in mean fructosamine were not significantly different between the 2 treatment groups. But, patients with final fructosamine below the median value showed significantly higher gain in VO2 peak (3.5±2.5 vs.1.7±2.4 ml/kg/min, p=0.014). In multivariate analysis gain in VO2 peak was associated with final fructosamine (p=0.019) but not with age, gender, duration of diabetes, MI location, insulin treatment or basal fructosamine. In conclusion, the DARE study shows that fructosamine at the end of the CR-program is an important determinant of gain in VO2 peak in T2D patients and that good glycemic control in CR is associated with significantly better gain in VO2 peak, independent of the treatment used (insulin or not). These data indicate that good glycemic control of type 2 diabetes in CR, after MI, is mandatory in order to get optimal gain in VO2 peak.

Spatial distribution of ventricular late potentials assessed by the newly developed signal-averaged vector-projected 187-channel electrocardiogram in patients with old myocardial infarction

Risk stratification of lethal arrhythmias is important for the management of ischemic heart disease. Recently, we developed a novel 187-channel signal-averaged vector-projected high-resolution electrocardiograph (187-ch SAVP-ECG) with a Mason–Likar lead system with 10 electrodes. The purpose of this study was to examine the feasibility of a noninvasive evaluation of the spatial distribution of high-frequency late potentials (HFLPs) in patients with myocardial infarction (MI) by using the 187-ch SAVP-ECG. Sixty-four MI patients (7 women and 57 men), between the age of 39 and 84 years (mean 67.7±9.7 years), with positive ventricular late potentials defined by an X, Y, Z-lead ECG were studied. The integrated ventricular 187-ch SAVP-ECG could identify the area of HFLPs that was projected virtually by mathematically calculated 187 electrograms on the body surface in all patients, and differentiate the locations of MI. The 187-ch SAVP-ECG can be a practical and noninvasive examination tool for identifying the location of infarction areas and possible arrhythmogenic substrates with slow conduction properties in patients with MI.

Sex-related differences in prognosis after myocardial infarction: changes from 1978 to 2007

Women with myocardial infarction (MI) have shown a 28-day survival disadvantage compared with men. However, results were less consistent when considering long-term mortality in 28-day survivors. The aim was to estimate the trends for sex-related differences in the three endpoints considered for this study: (1) 28-day mortality or severe ventricular dysfunction (acute pulmonary oedema or cardiogenic shock) during the hospital stay, (2) 28-day mortality and (3) two-year cardiovascular mortality or non-fatal MI in 28-day survivors after a first MI. A cohort of 3,982 consecutive patients with first Q-wave MI admitted to a university tertiary reference hospital between 1978 and 2007 was followed for 2 years. Short-term prognosis improved in women over the studied period; similar rates were observed in both sexes in the 2000s. After adjusting for age, co-morbidities and anterior location of MI, female sex had an odds ratio=1.71 (95% confidence interval [CI] 1.34-2.17) of short-term severe MI or death over the studied period. Overall, sex differences in long-term prognosis remained similar over the studied period (hazard ratio=1.40; 95% CI 1.02-1.91). In conclusion, short-term prognosis improved over the past 30 years for first Q-wave MI patients, becoming similar for both men and women in the most recent decade. Long-term prognosis did not improve in either men or women, indicating that secondary prevention should be reinforced to achieve consistent reductions in the number of cardiovascular events.

Thrombolytic effect of streptokinase infusion assessed by ST-segment resolution between diabetic and non-diabetic myocardial infarction patients

Recently, it has been hypothesized that type 2 diabetes might interfere with acute intravenous thrombolysis effectiveness as estimated by angiographic or electrocardiographic criteria. In our study, we compared the thrombolytic effect of streptokinase infusion between diabetic and non-diabetic myocardial infarction (MI) patients. In a prospective interventional study, 240 consecutive patients who were admitted to the emergency ward and diagnosed with ST-elevation MI (STEMI) were enroled and classified into diabetics (n = 85) and non-diabetics (n = 155). Streptokinase was given to each patient at a dose of 1.5 million units in 1 h. Twelve-lead ECG was recorded immediately before the start of thrombolytic therapy and at 180 min afterwards for the patients with STEMI. The ST-segment elevation resolution was calculated and stratified as complete resolution ( > 70% ST-resolution), partial resolution (30-70% ST-resolution), or failed resolution ( < 30% ST-resolution). Complete ST-resolution occurred in 31.6% of diabetic and 51.0% of non-diabetic patients, respectively (p < 0.001). The incidence of partial ST-resolution in diabetic and non-diabetic patients was 40.5% and 40.0%, whereas 27.8% of patients in the diabetic group and 9.0% of patients in the non-diabetic group showed failed ST resolution. ST-resolution was independent of the location of MI. Multivariate analysis showed that diabetes mellitus, as well as higher Killip class and lower ejection fraction, could effectively predict ST-resolution failure. Failure of ST-segment resolution 180 min after streptokinase infusion is notably higher in diabetic vs non-diabetic patients. This failure rate is correlated with higher Killip class and lower ejection fraction.

Assessment of distribution and evolution of mechanical dyssynchrony in a porcine model of myocardial infarction by cardiovascular magnetic resonance.

BackgroundWe sought to investigate the relationship between infarct and dyssynchrony post- myocardial infarct (MI), in a porcine model. Mechanical dyssynchrony post-MI is associated with left ventricular (LV) remodeling and increased mortality.MethodsCine, gadolinium-contrast, and tagged cardiovascular magnetic resonance (CMR) were performed pre-MI, 9 ± 2 days (early post-MI), and 33 ± 10 days (late post-MI) post-MI in 6 pigs to characterize cardiac morphology, location and extent of MI, and regional mechanics. LV mechanics were assessed by circumferential strain (eC). Electro-anatomic mapping (EAM) was performed within 24 hrs of CMR and prior to sacrifice.ResultsMean infarct size was 21 ± 4% of LV volume with evidence of post-MI remodeling. Global eC significantly decreased post MI (-27 ± 1.6% vs. -18 ± 2.5% (early) and -17 ± 2.7% (late), p < 0.0001) with no significant change in peri-MI and MI segments between early and late time-points. Time to peak strain (TTP) was significantly longer in MI, compared to normal and peri-MI segments, both early (440 ± 40 ms vs. 329 ± 40 ms and 332 ± 36 ms, respectively; p = 0.0002) and late post-MI (442 ± 63 ms vs. 321 ± 40 ms and 355 ± 61 ms, respectively; p = 0.012). The standard deviation of TTP in 16 segments (SD16) significantly increased post-MI: 28 ± 7 ms to 50 ± 10 ms (early, p = 0.012) to 54 ± 19 ms (late, p = 0.004), with no change between early and late post-MI time-points (p = 0.56). TTP was not related to reduction of segmental contractility. EAM revealed late electrical activation and greatly diminished conduction velocity in the infarct (5.7 ± 2.4 cm/s), when compared to peri-infarct (18.7 ± 10.3 cm/s) and remote myocardium (39 ± 20.5 cm/s).ConclusionsMechanical dyssynchrony occurs early after MI and is the result of delayed electrical and mechanical activation in the infarct.

Abstract 16739: Regional Variation in the Relationship of Infarct Size to Left Ventricular Ejection Fraction: Implications for Risk Stratification for Sudden Cardiac Death

Introduction: In patients with coronary artery disease (CAD), guidelines for primary prevention of sudden cardiac death (SCD) use left ventricular ejection fraction (LVEF) ≤35%. The substrate for SCD is myocardial infarction (MI); indeed, MI size expressed as percent of LV mass (IM%) measured by cardiac magnetic resonance imaging (CMR) has been shown to be a better predictor of inducible ventricular tachycardia (VT) on electrophysiologic study than LVEF, with a cutoff of &gt; 10% providing the highest sensitivity. Purpose: To examine the influence of MI location on the relationship between IM% and LVEF. Methods: We analyzed cine and late gadolinium enhanced (LGE) CMR images for 412 patients with CAD (81% male, age 62.3 ± 11.4) and a history of MI from the DEfibrillators To REduce Risk by MagnetIc ResoNance Imaging Evaluation Trial (DETERMINE trial, www.clinicaltrials.gov ). LVEF and IM% were quantified (Medis QMass MR 7.2). We performed segmental visual scoring of cine (from 0 = normal to 4 = dyskinesis) and LGE images (from 0 = none to 4 = 76-100%). Each of the 17 segments was assigned to a coronary artery territory based on American Heart Association segmentation recommendations. MI location was calculated as the territory with the highest LGE score: left anterior descending (LAD), left circumflex (LCX), and right coronary artery (RCA). Results: Overall, 206/412 (50%) of patients had IM% &gt; 10% while maintaining LVEF &gt; 35%. The distribution of MI location was LAD (205), LCX (84), and RCA (123). The impact of increasing IM% on LVEF differed based on MI location (figure). The expected IM% required to reduce LVEF to 35% for a LCX MI was 19%, for LAD was 26%, and for RCA was 34%. Conclusions: As a marker of MI burden, LVEF is insensitive and is strongly influenced by MI location. As it best represents the substrate for SCD and is related to both mortality and inducible VT, further efforts are required to investigate IM% as a predictor of SCD, independent of LVEF.

The relationship between serial postinfarction T wave changes and infarct size and ventricular function as determined by cardiac magnetic resonance imaging

Background The value of sequential T wave changes on the electrocardiogram (ECG) has less well been described than ST-segment changes in the follow-up of patients with myocardial infarction (MI). We investigated whether the amplitude of T wave positivity correlates with infarct size (IS) and left ventricular ejection fraction (LVEF) measured using cardiac magnetic resonance imaging 3 months after reperfusion therapy. Materials and Methods Fifty-five patients with a first acute MI referred for primary percutaneous coronary intervention were included. Electrocardiograms were analyzed within 4 hours after reperfusion and at 3 months, measuring T wave ampitudes in 2 contiguous infarct-related leads, summed up as one value called T wave amplitude. Cardiac magnetic resonance imaging was performed at 3 months of follow-up. Correlations between T wave amplitude, IS, and LVEF were tested with Pearson r correlation coefficient test. Subanalyses were performed using a 2-sample t test. Results A good correlation was found between LVEF and IS ( r = −0.7, P < .0001). Most of the patients had inferior MI location (69%). In this group, there were significant positive correlations between the amount of T wave positivity and both IS ( r = −0.40, P = .012) and LVEF ( r = 0.33, P = .043). Results were similar in patients with and without an increase in T wave amplitude during follow-up. Conclusions In this study of patients with reperfused MI, patients with inferior locations demonstrated a statistically significant relationship between the amount of positivity of T wave amplitude and both IS and LVEF measured at 3 months. Furthermore, these results were independent of whether the T wave positivity was persistent or evolutionary between the immediate postreperfusion and 3-month ECG recordings.

Relationship between location and size of myocardial infarction and their reciprocal influences on post-infarction left ventricular remodelling

To assess the intricate relationship between myocardial infarction (MI) location and size and their reciprocal influences on post-infarction left ventricular (LV) remodelling. A cohort of 260 reperfused ST-segment elevation MI patients was prospectively studied with cardiovascular magnetic resonance at 1 week (baseline) and 4 months (follow-up). Area at risk (AAR) and MI size were quantified by T2-weighted and late-gadolinium enhancement imaging, respectively. Adverse LV remodelling was defined as an increase in LV end-systolic volume ≥15% at follow-up. One hundred and twenty-seven (49%) patients had anterior MI and 133 (51%) patients had non-anterior MI. Although the degree of myocardial salvage was similar between groups (P = 0.74), anterior MI patients had larger AAR and MI size than non-anterior MI patients yielding worse regional and global LV function at baseline and follow-up. At univariable analysis, anterior MI was associated with increased risk of adverse LV remodelling (P = 0.017) and lower LV ejection fraction (EF) at follow-up (P = 0.001), but not when accounted for baseline MI size. Accordingly, at multivariable analysis, baseline MI size but not its location was an independent predictor of adverse LV remodelling (odds ratio = 1.061, P < 0.001) and EF at follow-up (β-coefficient = -0.255, P < 0.001). Anterior MI patients experience more pronounced post-infarction LV remodelling and dysfunction than non-anterior MI patients due to a greater magnitude of irreversible ischaemic LV damage without any independent contribution of MI location.

CORONARY EMBOLISM WITH FRAGMENTED THROMBUS FROM THE LEFT VENTRICLE IN PATIENT WITH POSTINFARCTION ANEURYSM

The thrombus formation in the left ventricle (LV) cavity is a frequent complication of myocardial infarction (MI) as well as a risk factor for peripheral arterial embolism. Probability of intraventricular thrombus depends on MI location and its therapy. A case of coronary embolism in a patient with anterior MI and thrombus in the LV aneurysm is considered in details. Successful percutaneous coronary intervention (PCI) in the first 90 minutes after admission was performed. Decision to appoint a three-component antithrombotic therapy (acetylsalicylic acid, clopidogrel, warfarin) was made on the 4th day of disease onset taking into account the combination of MI, stent placement in the anterior interventricular artery and the presence of left ventricular aneurysm with parietal thrombus. Recurrence of MI developed on the 9th day of disease onset. Aspiration thromboembolectomy was performed taking into account thrombosis of two coronary arteries. Warfarin therapy was discontinued in connection with subsequent clot lysis and development of not intensive nosebleed. Subsequent MI course was uneventful. In conclusion, even in spite of the timely achievement of PCI and early reperfusion, MI course can be complicated by thrombosis of the left ventricle and subsequent development of thromboembolic complications.

Pexelizumab and Infarct Size in Patients With Acute Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention: A Delayed Enhancement Cardiac Magnetic Resonance Substudy From the APEX-AMI Trial

The purpose of the study was to understand determinants of infarct size in a primary percutaneous intervention (PCI) population treated with pexelizumab compared with placebo. In the multicenter APEX-AMI (Pexelizumab in Conjunction With Angioplasty in Acute Myocardial Infarction) trial, pexelizumab did not reduce 90-day mortality. Cardiac magnetic resonance (CMR) with delayed enhancement was used in a substudy evaluating infarct size and left ventricular ejection fraction (LVEF). Consecutive patients undergoing primary PCI for first myocardial infarction (MI) as part of the APEX-AMI trial were enrolled in this substudy at 5 centers. The CMR was completed on days 3 to 5 (n=99) and day 90 (n=83) following PCI. Central core lab-masked analyses for quantified LVEF, volumes, and infarct size by planimetry were performed. Patients were 60+/-12 years of age, male (n=83 [84%]), had similar time from symptom onset to presentation (median 2.6 h vs. 2.5 h; p=1.0), and similar baseline ST-segment deviation (13.5 mm vs. 14 mm; p=0.59) in both groups. Pexelizumab-treated patients had smaller infarct size (day 3 LV 10.5% vs. 16.2%, p=0.022; day 90 LV 5.9% vs. 12.4%, p=0.015) and higher LVEF (day 3 50.3% vs. 46.2%, p=0.073; day 90 53.9% vs. 49.3%, p=0.036) compared with placebo-treated patients. The median peak creatine kinase in the pexelizumab group was also significantly less than placebo (922 mg/dl vs. 1,973 mg/dl; p=0.03). Notably, the pexelizumab group had lower Thrombolysis In Myocardial Infarction (TIMI) flow grade pre-PCI (46.9% vs. 75.0%; p=0.018), a difference not seen in the overall APEX-AMI study. A multivariate model including baseline features and pexelizumab treatment found anterior MI location and pre-PCI TIMI flow to be significant independent predictors infarct size (p=0.001), whereas pexelizumab was not (p=0.29). No death, heart failure, or shock was noted in either substudy group at 90 days. In a CMR substudy of pexelizumab in MI, baseline TIMI flow grade and anterior location were the only predictors of infarct size, with a reduction of pre-PCI TIMI flow grade 0 by 28%, leading to a 35% reduction in infarct size. (The APEX-AMI Trial; NCT00091637).

Abstract 4759: Endothelin-1: A Useful Prognostic Marker After Acute Myocardial Infarction

INTRODUCTION: High Endothelin-1 (E-1) levels have been linked to poor clinical outcomes after myocardial infarction (MI). Vasoconstriction of the coronary microcirculation seems to be the underlying mechanism. However, the relationship between E-1 levels and microvascular integrity in the setting of MI has not been analyzed. OBJECTIVES To assess the effect of E-1 on microvascular integrity, necrosis volume, left ventricular ejection fraction (LVEF) and myocardial savage (M-sav) in evolving MI. METHODS: We measured E-1 levels in a consecutive series of 127 patients (pts) presenting with a first MI. Blood samples for E-1 measurements were taken 6 to 24 hours after MI onset. MRI was performed within 1 week following presentation and microvascular obstruction (MO), necrosis volume and LVEF was assessed by ce-CMR. M-sav was definded as the % of angiographic area at risk by the BARI score that spared necrosis on the MRI. RESULTS: Mean age was 60.9±11,8 years and 94(80%) were males. MI location was anterior in 47.2%. As shown in table , high E-1 levels were associated to admission Killip ≥2, higher prePCI TIMI 0, worse postPCI MBG and higher mortality at 30 days. MO was documented in 48%. High E-1 values were also associated with MO and worse M-sav while no significant correlation was obtained with necrosis volume and LVEF. Compared to Troponin I/CKMB peak values, E-1 levels showed better correlation with MO, M-sav, Killip on admission, MBG postPCI and mortality at 30 days. CONCLUSIONS: In humans, high E-1 levels after MI are closely associated with the presence of MO and worse M-sav. E-1 assessment renders prognostic information, independent from that provided by LVEF and necrosis volume

Wideband High-Frequency Echocardiography to Evaluate Myocardial Infarct Size

This study was designed to validate the feasibility of wideband high-frequency ultrasound imaging to resolve in vivo the degree, location, and morphologic changes of myocardial infarction (MI) in a rat model. The left anterior descending coronary artery was ligated in the test group (n = 41), and the sham control group did not have ligation (n = 7). The rats were examined with 10- to 22-MHz echocardiography to evaluate the MI size, location, and geometric formation. The endocardial chamber shape was deformed, with enlargement of the anteroposterior dimension and fractional shortening, and was comparable with the degree of MI both in short- and long-axis sections of the left ventricle. Histologic analysis showed remodeling to different extents corresponding to different MI sizes (small, medium, and large). The results suggest that this technique can be used in vivo to evaluate the MI location, size, and morphologic changes corresponding to the extent of the injury.

Pre‐operative coronary revascularisation before non‐cardiac surgery: think long and hard before making a pre‐operative referral

Pre‐operative coronary revascularisation before non‐cardiac surgery: think long and hard before making a pre‐operative referral

Prospective Electrocardiogram-Gated Delayed Enhanced Multidetector Computed Tomography Accurately Quantifies Infarct Size and Reduces Radiation Exposure

This study sought to determine whether low-dose, prospective electrocardiogram (ECG)-gated delayed contrast-enhanced multidetector computed tomography (DCE-MDCT) can accurately delineate the extent of myocardial infarction (MI) compared with retrospective ECG-gated DCE-MDCT. For defining the location and extent of MI, DCE-MDCT compares well with delayed enhanced cardiac magnetic resonance. However, the addition of a delayed scan requires additional radiation exposure to patients. MDCT protocols using prospective ECG gating can substantially reduce effective radiation dose exposure, but these protocols have not yet been applied to infarct imaging. Ten porcine models of acute MI were imaged 10 days after MI using prospective and retrospective ECG-gated DCE-MDCT (64-slice) 10 min after a 90-ml contrast bolus. The MDCT images were analyzed using a semiautomated computed tomography density (CTD) threshold technique. Infarct size, signal-to-noise (SNR) ratios, contrast-to-noise (CNR) ratios, and image quality metrics were compared between the 2 ECG-gating techniques. Infarct volume measurements obtained by both methods were strongly correlated (R = 0.93, p < 0.001) and in good agreement (mean difference: -0.46 ml +/- 4.00%). Compared with retrospective ECG gating, estimated radiation dosages were markedly reduced with prospective ECG gating (930.1 +/- 62.2 mGy x cm vs. 42.4 +/- 2.3 mGy x cm, p < 0.001). The SNR and CNR of infarcted myocardium were somewhat lower for prospective gated images (22.0 +/- 11.0 vs. 16.3 +/- 7.8 and 8.8 +/- 5.3 vs. 7.0 +/- 3.9, respectively; p < 0.001). However, all examinations using prospective gating protocol achieved sufficient diagnostic image quality for the assessment of MI. Prospective ECG-gated DCE-MDCT accurately assesses infarct size compared with retrospective ECG-gated DCE-MDCT imaging. Although infarct SNR and CNR were significantly higher for the retrospective gated protocol, prospective ECG-gated DCE-MDCT provides high-resolution imaging of MI, while substantially lowering the radiation dose.

Análisis de mortalidad en el infarto de miocardio tratado con angioplastia primaria

Primary angioplasty is an effective method to achieve myocardial reperfusion in ST-elevated myocardial infarction (MI). The objective of this study was to determine the independent factors that could predict mortality in MI patients treated with primary angioplasty and to analyze the prognostic value of tissue reperfusion parameters in those patients. A prospective observational study was performed in 380 consecutive patients with ST-elevated MI treated with primary angioplasty at a single hospital. Early mortality was 8.9%. Upon univariate analysis, the following variables were associated with significantly higher mortality: age, ejection fraction (EF), multivascular disease, anterior location of MI, lack of resolution of ST segment, flow 0-1 of TIMI, grade 0-1 of blush index and delay time above 4 hours. Multivariate analysis yielded the following independent variables as predictors of mortality: age, degree of heart failure (Killip index) and degree of myocardial perfusion (blush index). The independent predictive factors of mortality in patients with ST-elevated MI and treated with primary angioplasty are: age, degree of heart failure (Killip index) and degree of myocardial reperfusion (blush index). The resolution of ST segment and blush index represent additional prognostic variables in patients with good epicardial reperfusion.

Clinical Outcome After Surgical Correction of Mitral Regurgitation Due to Papillary Muscle Rupture

Papillary muscle rupture (PMR) is an infrequent but catastrophic complication of acute myocardial infarction (MI). Although always considered, surgical treatment is often denied because of high operative mortality. Moreover, the effects of surgery for PMR on long-term outcome, particularly compared with expected outcome after MI, are undefined. Fifty-four consecutive patients (age, 70+/-8 years; 74% male) underwent mitral surgery for post-MI PMR from January 1980 through December 2000. Severe presentation (cardiogenic shock, pulmonary edema, or cardiac arrest) was noted in 91% preoperatively. Performance of coronary artery bypass graft was associated with lower operative mortality (odds ratio, 0.18; 95% CI, 0.04 to 0.83; P=0.011), whereas there was a trend for lower mortality after surgery after 1990 (odds ratio, 0.28; 95% CI, 0.06 to 1.3). Thus, operative mortality (overall, 18.5%) decreased from 67% up to 1990 without coronary artery bypass graft to 8.7% after 1990 with coronary artery bypass graft. Overall 5-year survival was 65+/-7%, and survival free of congestive heart failure was 52+/-7%. Five-year survival of 30-day operative survivors was 79+/-4%, identical (P=0.24) to that of matched controls with MI (similar age, sex, ejection fraction, MI location, and MI year). Survival free of congestive heart failure was similar in PMR cases and MI controls (10-year survival, 28+/-8% versus 36+/-6%; P=0.46). Surgery for post-MI PMR involves a notable operative mortality, but there are recent trends for lower operative risk, particularly with associated coronary artery bypass graft. Long term after surgery, outcome is restored to that of similar MI without PMR. These encouraging observations emphasize the importance of prompt diagnosis and aggressive therapeutic approach for patients incurring PMR after MI.

New electrocardiographic diagnostic criteria for the pathologic R waves in leads V1 and V2 of anatomically lateral myocardial infarction

AimsTo study the different QRS patterns in leads V1 and V2 in first inferior, lateral, and combined inferolateral myocardial infarction (MI) to recognize which are the ECG criteria that best define the presence of lesions isolated to the anatomically lateral wall of the left ventricle. Methods and resultsWe studied consecutive patients with first inferior (15), lateral (9), or inferolateral (21) MI with reference to contrast enhanced cardiac magnetic resonance (CE-CRM). We measured the R-wave amplitude and duration, the R/S ratio, and the T-wave amplitude and polarity in leads V1 and V2. The specificity of the V1 criteria for lateral MI, that is, R/S amplitude ratio 1 or greater and R duration 40 milliseconds or longer, is very high but its sensitivity is low. We defined 2 new criteria, R/S of 0.5 or greater and R amplitude in V1 greater than 3 mm, with each achieving a sensitivity of 73.3% and specificity of 93.3% for lateral/inferolateral MI location. Conclusions(1) New ECG criteria for lateral MI (R/S ratio in V1 ≥0.5 and R amplitude in V1 >3 mm) present very high specificity and lower but very acceptable sensitivity for lateral MI. (2) New criteria based on R waves in V2 or T waves in V1 to V2 do not discriminate between inferior and lateral MI. (3) The classical criteria (R/S amplitude ratio ≥1 and R duration ≥40 ms in V1) attain very high specificity but much lower sensitivity than the new criteria.

Tissue Sodium Concentration in Myocardial Infarction in Humans: A Quantitative23Na MR Imaging Study1

To prospectively determine whether the absolute tissue sodium concentration (TSC) increases in myocardial infarctions (MIs) in humans and whether TSC is related to infarct size, infarct age, ventricular dysfunction, and/or electrophysiologic inducibility of ventricular arrhythmias. Delayed contrast material-enhanced 1.5-T hydrogen 1 ((1)H) magnetic resonance (MR) imaging was used to measure the size and location of nonacute MIs in 20 patients (18 men, two women; mean age, 63 years +/- 9 [standard deviation]; age range, 48-82 years) examined at least 90 days after MI. End-systolic and end-diastolic volumes, ejection fraction, and left ventricle (LV) mass were measured with cine MR imaging. The TSC in normal, infarcted, and adjacent myocardial tissue was measured on sodium 23 ((23)Na) MR images coregistered with delayed contrast-enhanced (1)H MR images. Programmed electric stimulation to induce monomorphic ventricular tachycardia (MVT) was used to assess arrhythmic potential, and myocardial TSC was compared between the inducible MVT and noninducible MVT patient groups. The mean TSC for MIs (59 micromol/g wet weight +/- 10) was 30% higher than that for noninfarcted (remote) LV regions (45 micromol/g wet weight +/- 5, P < .001) and that for healthy control subjects, and TSC did not correlate with infarct age or functional and morphologic indices. The mean TSC for tissue adjacent to the MI (50 micromol/g wet weight +/- 6) was intermediate between that for the MI and that for remote regions. The elevated TSC measured in the MI at (23)Na MR imaging lacked sufficient contrast and spatial resolution for routine visualization of MI. Cardiac TSC did not enable differentiation between patients in whom MVT was inducible and those in whom it was not. Absolute TSC is measurable with (23)Na MR imaging and is significantly elevated in human MI; however, TSC increase is not related to infarct age, infarct size, or global ventricular function. In regions adjacent to the MI, TSC is slightly increased but not to levels in the MI.

Effects of the Location of Myocardial Infarction on the Spectral Characteristics of Ventricular Fibrillation

The location of the myocardial infarction (MI) might modify the spectral characteristics of ventricular fibrillation (VF) in humans. To evaluate the effect of the location of the infarcted area on the spectral parameters of VF. Patients with chronic MI (29 anterior, 32 inferior) and induced VF during cardioverter defibrillator implant were retrospectively studied. Dominant frequency (f(d)), organization index (OI), and power of the harmonic peaks were calculated in the device-stored electrograms (EGM) during sinus rhythm (SR) and VF. The f(d) of the VF was not affected by the left ventricular ejection fraction (LVEF) or the MI location (anterior: 4.54 +/- 0.74 Hz, inferior: 4.77 +/- 0.48 Hz, n.s.). The OI was also similar in both groups. However, in patients with inferior MIs, normalized peak power at f(d) was higher (118.3 +/- 18.5 vs 100.6 +/- 28.2, P < 0.01) and the normalized peak power of the harmonics was lower than in the anterior MI group. The analysis of EGM during SR showed similar results. The size of the necrotic area and its distance to the recording electrode might partially explain these results. In our series, the spectral characteristics of the EGMs during VF showed significant differences depending on the MI localization. A higher fraction of energy (in the low-frequency region) was seen in inferior MIs, whereas the peak power at the harmonics increased in anterior MIs. A similar effect was seen during SR and VF, suggesting that it is caused by local electrophysiology abnormalities induced by the MI rather than by different intrinsic characteristics of the VF.