Recovery In Acute Myocardial Infarction Research Articles

Impact of Early Invasive Strategy on Left Ventricular Function Recovery in Acute Myocardial Infarction Patients in Pakistan.

Background Acute myocardial infarction (AMI) is a leading cause of morbidity and mortality worldwide, particularly in low- and middle-income countries like Pakistan, where healthcare resources are limited. Early Invasive Strategy (EIS), typically involving percutaneous coronary intervention (PCI), has been shown to improve outcomes in AMI patients. However, the effectiveness of EIS in resource-limited settings, such as Pakistan, remains under-explored. Objective This prospective observational cohort study aimed to assess the impact of an Early Invasive Strategy (EIS) on left ventricular (LV) function recovery in acute myocardial infarction (AMI) patients in Pakistan. The primary objective was to measure the change in left ventricular ejection fraction (LVEF) over six months. Secondary objectives included evaluating mortality, rehospitalization rates, and incidences of major adverse cardiovascular events (MACE). Multivariate regression analysis was employed to adjust for potential confounders. Methods The study was conducted from January to December 2023 at the National Institute of Cardiovascular Diseases (NICVD) satellite centers in Sukkur, Nawab Shah, and Khairpur. A total of 300 AMI patients presenting within 24 hours of symptom onset were included. Participants were divided into two groups: the EIS group (n = 150) received percutaneous coronary intervention (PCI) within 24 hours of admission, while the delayed treatment group (n = 150) received standard therapy, with invasive procedures performed after 24 hours if clinically indicated. Data were collected at baseline, during hospitalization, and at three- and six-months post-AMI. Results The EIS group demonstrated a significantly greater improvement in LVEF compared to the delayed treatment group (13.1% [95% CI, 10.8%-15.4%] vs. 7.5% [95% CI, 5.8%-9.2%], p < 0.001). Mortality was lower in the EIS group (3% [n = 4] vs. 9% [n = 13], p = 0.01), as were rehospitalizations for heart failure (7% [n = 10] vs. 14% [n = 21], p = 0.02) and incidences of MACE (8% [n = 12] vs. 16% [n = 24], p = 0.01). Multivariate regression analysis confirmed that EIS was independently associated with better LVEF improvement (coefficient = 5.78 [95% CI, 4.21-7.35], p < 0.001). Conclusion Early invasive treatments significantly enhance left ventricular function recovery and reduce mortality and rehospitalization rates in AMI patients in Pakistan. These findings advocate for the implementation of timely PCI interventions in resource-limited settings to improve clinical outcomes, particularly emphasizing cost-effectiveness and the availability of PCI.

Three-Biomarker Joint Strategy for Early and Accurate Diagnosis of Acute Myocardial Infarction via a Multiplex Electrochemiluminescence Immunoarray Coupled with Robust Machine Learning.

Acute myocardial infarction (AMI) represents a leading cause of death globally. Key to AMI recovery is timely diagnosis and initiation of treatment, ideally within 3 h of symptom onset. Cardiac troponin T (cTnT) is the gold standard yet a low cTnT result cannot rule out AMI at early times. Here, we develop a three-biomarker joint strategy for early and accurate diagnosis of AMI via an electrochemiluminescence (ECL) immunoarray coupled with robust machine learning. The ECL immunoarray is based on an array microchip with a single-electrode and chemiluminescent immuno-Gold (ciGold) nanoassemblies. The ciGold immunoarray was obtained by successively assembling nanocomposites of Cu2+/cysteine complexes and N-(aminobutyl)-N-(ethylisoluminol) bifunctionalized gold nanoparticles combined with chitosan and antibody conjugated gold nanoparticles on the surface of a microchip. Three biomarkers, including cardiac troponin I, heart type fatty acid binding protein, and copeptin, were simultaneously detected in 260 serum samples from patients presenting with chest pain by an innovative multiplexed ECL immunoarray, and classified via the three-biomarker joint assessment model using support vector machines. The model achieved perfect discrimination (100% sensitivity and specificity) for AMI vs non-AMI patients, substantially higher than cTnT alone. Within 12 h of symptom onset, high-sensitivity cardiac troponin T (hs-cTnT) misclassified >20% of patients, while the joint biomarker assessment model retained perfect accuracy. As the time between symptom onset and testing became shorter, the degree to which the joint assessment model outperformed hs-cTnT increased. The proposed three-biomarker joint strategy is obviously superior to hs-cTnT for early and accurate diagnosis of AMI, hopefully reducing AMI mortality and saving limited medical resources.

C1q/TNF-related protein-2 improved angiogenesis to protect myocardial function during ischaemia‒reperfusion.

Collateral growth plays an important role in the recovery of acute myocardial infarction. C1q/TNF-related protein-2 (CTRP2), a CTRP family member, showed some protective effects on cell survival. In this study, the relationship between CTRP2 and collateral growth was examined. C57BL/6 mice were subjected to myocardial ischaemia/reperfusion (I/R), and the expression of CTRP2 and the effect of CTRP2 on infarction size, cardiac function and angiogenesis were examined. The ischaemic hindlimb model was also used to examine the effect of CTRP2. In vitro, CTRP2-mediated regulation of angiogenesis, AKT activation and VEGFR2 expression in endothelial cells was examined. The CTRP2 level associated with good collateral growth was observed in a cohort. I/R reduced CTRP2 expression, and intraperitoneal injection of recombinant CTRP2 protein improved infarction size, cardiac function and angiogenesis. Overexpression of CTRP2 promoted blood refusion and collateral growth in ischaemic hindlimb mice. In vitro, CTRP2 enhanced tube formation and migration in a dose-dependent manner, while CTRP2 increased AKT phosphorylation and VEGFR2 expression. In an observational clinical cohort, CTRP2 levels were significantly increased in patients with good collateral growth, and CTRP2 was negatively associated with poor collateral growth in patients. CTRP2 improved cardiac function by promoting collateral growth by promoting AKT-VEGFR2.

Cardiac magnetic resonance T1 mapping allows for predicting adverse left ventricular remodeling post-reperfused st-elevation myocardial infarction

Abstract Background Cardiac magnet resonance (CMR) T1 mapping allows the quantitative characterization of the severity of tissue injury and predict functional recovery in acute myocardial infarction (AMI). Purpose The study aimed to investigate whether native T1 and ECV of infarct myocardium are influenced by microvascular obstruction (MVO) and have predictive value for adverse left ventricular (LV) remodeling post-infarction. Method A cohort of 54 patients with successfully reperfused STEMI underwent CMR imaging at a 3T scanner in AMI and 3 months post-infarction. Native T1 data was acquired using a modified Look-Locker inversion recovery (MOLLI) sequence, and ECV maps were calculated using blood sampled hematocrit. Manual regions-of-interest were drawn within the infarct myocardium to measure native T1 and ECV (native T1infarct and ECVinfarct, respectively). MVO identified as a low-intensity area within the infarct zone on LGE was eliminated. Results MVO was present in 36 patients (66.67%) in AMI. ECVinfarct in patients with MVO was different from those without (58.66±8.71% vs. 49.64±8.82%, P=0.001), while no significant difference in T1infarct was observed between patients with and without MVO (1474.7±63.5ms vs. 1495.4±98.0ms, P=0.352). ECV correlated well with the change in end-diastolic volume (all patients: r=0.564, P&amp;lt;0.001) and predicted LV remodeling in patients with and without MVO (rMVO absent = 0.626, P=0.005; rMVO present = 0.686, P&amp;lt;0.001; all patients: r=0.622, P&amp;lt;0.001); Native T1 was only associated with a 3-month change in LV end-diastolic volume (rMVO absent= 0.483, P=0.042) and predicted LV remodeling in patients without MVO (rMVO absent = 0.659, P=0.003). Furthermore, ECV had an association with LV remodeling (β=0.312, P=0.007) in multivariable logistic analysis. Conclusion Absolute native T1 in infarct myocardium might be affected by MVO but ECV isn't. ECV could predict LV remodeling in MI patients with and without MVO, while native T1 predict it in MI with MVO absent. Funding Acknowledgement Type of funding source: Public hospital(s). Main funding source(s): 1·3·5 project for disciplines of excellence, West China Hospital, Sichuan University

RGD-PEG-PLA Delivers MiR-133 to Infarct Lesions of Acute Myocardial Infarction Model Rats for Cardiac Protection.

Studies have shown that microRNA-133 (miR-133) plays a positive role in the growth of cardiac myocytes, the maintenance of cardiac homeostasis, and the recovery of cardiac function, which is of great significance for the recovery of acute myocardial infarction. However, the delivery of miRNA to the site of action remains a challenge at present. The purpose of this study was to design an ideal carrier to facilitate the delivery of miR-133 to the infarct lesion for cardiac protection. A disease model was constructed by ligating the left anterior descending coronary artery of rats, and polyethylene glycol (PEG)-polylactic acid (PLA) nanoparticles modified with arginine-glycine-aspartic acid tripeptide (RGD) carrying miR-133 were injected via the tail vein. The effects of miR-133 were evaluated from multiple perspectives, including cardiac function, blood indexes, histopathology, and myocardial cell apoptosis. The results showed that RGD-PEG-PLA maintained a high level of distribution in the hearts of model rats, indicating the role of the carrier in targeting the heart infarction lesions. RGD-PEG-PLA/miR-133 alleviated cardiac histopathological changes, reduced the apoptosis of cardiomyocytes, and reduced the levels of factors associated with myocardial injury. Studies on the mechanism of miR-133 by immunohistochemistry and polymerase chain reaction demonstrated that the expression level of Sirtuin3 (SIRT3) was increased and that the expression of adenosine monophosphate activated protein kinase (AMPK) decreased in myocardial tissue. In summary, the delivery of miR-133 by RGD-PEG-PLA carrier can achieve cardiac lesion accumulation, thereby improving the cardiac function damage and reducing the myocardial infarction area. The inhibition of cardiomyocyte apoptosis, inflammation, and oxidative stress plays a protective role in the heart. The mechanism may be related to the regulation of the SIRT3/AMPK pathway.

P 129 - Alteration of phospholipidome profile in the heart of an animal model of acute myocardial infarction

Acute myocardial infarction (AMI) is one of the main causes of mortality and health care cost in the world. Development of valuable clinical tools can help in diagnosis in the early stage of disease or predicting recovery. The pathogenesis of AMI is multifactorial and lipids can have an active role in this pathology and be good candidates as biomarkers of initial stages of the disease and extent of tissue damage. Changes in phospholipidome profile were observed in cardiomyoblasts as model of AMI. However, lipidomics studies in AMI are scarce. In this work, a mass spectrometry-based lipidomics approach was used to evaluate changes in phospholipid profile in heart of murine models under ischemia, ischemia-reperfusion and starvation conditions. Differences in fatty acids and phospholipid profiles, related to the course of AMI were observed. An increase of C16:0, C18:0, C20:4 and C22:6, and a decrease of C18:2 were observed in ischemia-reperfusion and starvation. An increment of PL bearing FA 22:6, such as PC(18:0/22:6), PE(16:0/22:6), and PE(18:0/22:6), occurred in the same conditions. These PL can be precursors of anti-inflammatory lipids (e.g. resolvins) involved in AMI recovery. Therefore, lipidomics profiling by mass spectrometry can offer valuable information to understand AMI that can be exploited for diagnosis and prognosis.

20 Myocardial extracellular volume predicts functional recovery in acute myocardial infarction more accurately than threshold-based measures of late gadolinium enhancement transmural extent

The transmural extent of late gadolinium enhancement (LGE) CMR predicts functional recovery in acute myocardial infarction (AMI). Automated methods are recommended 1 to define infarct extent on LGE imaging, such as ‘n-standard deviations’ (SD) and ‘full width at half maximum’ (FWHM). These define infarcted myocardium by signal intensity as compared to remote myocardium, which in turn depends on signal-to-noise and contrast. Individual variability in these parameters makes a single thresholding technique unlikely to be universally suitable. Extracellular volume (ECV) estimation by T1-mapping CMR is theoretically less affected by sequence and contrast variations. We compared infarct ECV with threshold-based measures of LGE transmural extent to predict contractile recovery in reperfused AMI. Consecutive patients with reperfused first ST-elevation AMI underwent acute (day 2) and convalescent (3 months) CMR. Cine imaging, modified Look-Locker inversion T1 mapping natively and 15 min post gadolinium-contrast administration and LGE imaging were performed. Five LGE thresholding techniques were compared: 2, 5 and 6 SD, FWHM and a histogram-based technique (Otsu). 2 The ability of acute infarct ECV to predict improvement in segmental wall motion was compared with these thresholding techniques. n = 35 (28(80%) male, age 57 ± 11 years). Infarct characteristics are shown in Table 1. ECV showed modest correlation with all threshold measures of LGE (r 2 = 0.16–0.31, p Acute infarct ECV outperforms threshold-based LGE transmural extent to predict segmental LV functional recovery in reperfused AMI. References Schulz-Menger J, et al . J Card Magn Reson 2013;15:35 Otsu N. IEEE Trans Sys Man Cyber. 1979;9:62–6

Intramyocardial transplantation of human adipose-derived stromal cell and endothelial progenitor cell mixture was not superior to individual cell type transplantation in improving left ventricular function in rats with myocardial infarction

BackgroundBoth adipose-derived stromal cells (ASCs) and endothelial progenitor cells (EPCs) have high potential for promoting tissue revascularization and functional recovery in acute myocardial infarction (AMI) models. We investigated the functional effects of intramyocardial transplantation of a human ASC and EPC mixture in immunodeficient rats after MI. MethodsMI was induced by ligating left anterior descending coronary artery. Survived rats were randomly assigned to 1 of 4 different groups: the control group (n=10, saline in 100μL), the ASC group (n=10, 106 ASCs), the EPC group (n=10, 106 EPCs), or the ASC+EPC group (n=10, 2×105 ASCs+8×105 EPCs). Left ventricular (LV) function was compared using echocardiography during the 28-day follow-up. GAP43+ nerve sprouting and smooth muscle α-actin+angiogenesis were also compared. ResultsSerial changes in LV ejection fraction (EF) and fractional shortening revealed significant increases in the ASC, EPC, and ASC+EPC groups when compared to the control group during the follow-up (49±3%, 49±4%, 47±4%, 39±2%, P<0.001, respectively for LVEF) (33±4%, 32±2%, 31±2%, 23±2%, P=0.002, respectively for fractional shortening). The number of α-actin+arterioles and GAP43+ nerve area was significantly greater in the ASC, EPC, and ASC+EPC groups when compared to the control group in the peri-infarct area (34.4±1.0/mm2, 35.9±1.1/mm2, 35.3±0.9/mm2, 17.4±0.7/mm2, P<0.001, respectively for angiogenesis) (346.2±10.7μm2/mm2, 357.2±12.8μm2/mm2, 368.0±9.7μm2/mm2, 174.6±7.9μm2/mm2, P<0.001, respectively for nerve sprouting). ConlusionsIntramyocardial injections of ASCs, EPCs, or ASCs+EPCs are effective modalities for the treatment of myocardial damage in rats and may expand the potential clinical application of ASC or EPC therapy in patients with ischemic heart disease.

Usefulness of the index of microcirculatory resistance for invasively assessing myocardial viability immediately after primary angioplasty for anterior myocardial infarction

The aim of this study is to evaluate the usefulness of the index of microcirculatory resistance (IMR) for predicting myocardial viability and left ventricular (LV) function recovery in acute myocardial infarction (AMI). After successful primary percutaneous coronary intervention in 40 patients with anterior AMI, IMR was measured using a pressure-temperature sensor-tipped coronary guidewire. Myocardial viability was quantified by 18F-fluorodeoxyglucose (FDG) positron emission tomography in 38 patients. Echocardiographic regional wall motion was analysed to calculate the anterior wall motion score (A-WMS) and percent change in A-WMS after revascularization and at 6-month follow-up. IMR correlated significantly with regional myocardial FDG uptake (r = -0.738, P < 0.001) and it demonstrated significant correlation with percent change in A-WMS (r = -0.464, P = 0.003). The area under the receiver operating curve of IMR for predicting LV function recovery was 0.89 [95% CI 0.888-0.894]. Index of microcirculatory resistance, a new index representing microvascular integrity, is a reliable early on-site determinant of myocardial viability and LV recovery after primary stenting for AMI.

Circulating p53 and cytochrome c levels in acute myocardial infarction patients

Apoptosis causes myocardiocyte loss during and after myocardial infarction. Therapeutic approaches designed to arrest apoptosis would be a significant new development in the recovery of acute myocardial infarction (AMI). In order to examine apoptotic markers in the circulation, serum levels of p53 and cytochrome c were assessed in patients with AMI. Blood samples were taken on admission (before initiation of therapy) and on the 3rd and 7th days of hospitalization. Serum levels of p53 and cytochrome c were measured by enzyme-linked immunassay. The serum level of p53 was higher in AMI patients on admission compared to the control group. A time-dependent decrease was observed in the serum level of p53, but there was no significant change in the serum level of cytochrome c during therapy. p53, but not cytochrome c, appears to have potential as a biomarker for reporting on apoptosis following myocardial infarction.

Markers of myocardial reperfusion as predictors of left ventricular function recovery in acute myocardial infarction treated with primary angioplasty

Myocardial blush grade (MBG), corrected TIMI frame count (cTFC), and ST-segment reduction are indices of myocardial reperfusion. We evaluated their predictive value for left ventricular (LV) function recovery by gated single-photon emission computed tomography (SPECT) after acute myocardial infarction (AMI) treated with primary percutaneous coronary intervention (PCI). In 40 patients with AMI, gated SPECT was performed at admission and repeated 7 and 30 days after PCI. Left ventricular function recovery was defined as an increase > or = 10 points in SPECT LV ejection fraction from baseline to 1 month. The MBG, cTFC, and ST-segment elevation index 1 h after PCI were determined to evaluate reperfusion. Twenty-four patients (Group 1) had LV function recovery and 16 (Group 2) did not. A significant correlation was found between LV function recovery and MBG (r = 0.66; p = 0.0001), and ST-segment elevation index at 1 h (r = -0.55; p = 0.0001), but not with cTFC. Univariate predictors of LV function recovery were MBG (p = 0.0003) and ST-segment elevation index 1 h after intervention (p = 0.0026), but not cTFC. In a multivariate analysis, MBG was the only predictor of LV function recovery. Myocardial blush grade > or = 2 and ST-segment elevation index reduction had the same accuracy (88%) for predicting LV function recovery. Lower accuracy (75%) was shown by fast cTFC (< 23 frames). Myocardial blush grade > or = 2 showed the better negative likelihood ratio, and ST-segment elevation index reduction had the higher positive likelihood ratio in predicting LV function recovery. Myocardial blush grade was the best parameter for prediction of LV function recovery: MBG > or = 2 and ST-segment elevation index reduction showed good accuracy in predicting LV function recovery. The cTFC failed to be a significant predictor.

Insulin: an endogenous cardioprotector.

This review discusses the myocardial protective property of the insulin/glucose-insulin-potassium regimen and the mechanisms involved in this beneficial action. Several recent studies suggest that insulin not only is useful to control hyperglycemia and maintain glucose homeostasis but also may have the unique property to protect the myocardium from reperfusion injury and ischemia and prevent apoptosis of myocardial cells. The insulin/glucose-insulin-potassium (GIK) regimen suppresses the production of tumor necrosis factor-alpha, interleukin-6, macrophage migration inhibitory factor and other pro-inflammatory cytokines, and free radicals; and enhances the synthesis of endothelial nitric oxide and anti-inflammatory cytokines interleukin-4 and interleukin-10. Thus, the insulin/GIK regimen brings about its cardioprotective action. This may also explain why the insulin/GIK regimen is useful in sepsis and septic shock, myocardial recovery in acute myocardial infarction, and critical illness. It is suggested that the infusion of adequate amounts of insulin to patients with acute myocardial infarction, congestive heart failure, cardiogenic shock, and critical illness preserves myocardial integrity and function and ensures rapid recovery. In view of the suppressive action of insulin on the synthesis of proinflammatory cytokines and free radicals, it is possible that the insulin/GIK regimen, when used in a timely and appropriate fashion, may also protect other tissues and organs and facilitate in the recovery of patients who are critically ill.

Coronary flow velocity immediately after primary coronary stenting as a predictor of ventricular wall motion recovery in acute myocardial infarction

OBJECTIVESThe purpose of this study was to examine the relationship between the pattern of coronary blood flow velocity immediately after successful primary stenting and the recovery of left ventricular (LV) wall motion in patients with acute myocardial infarction (AMI).BACKGROUNDIt is difficult to predict the recovery of LV wall motion immediately after direct angioplasty in AMI. Recent reports indicate that dysfunctional coronary microcirculation is an important determinant of prognosis for AMI patients after successful reperfusion.METHODSWe measured left anterior descending coronary flow velocity variables using a Doppler guide wire immediately after successful primary stenting in 31 patients with their first anterior AMI. The patients were divided into two groups: those with and those without early systolic reverse flow (ESRF). Changes in LV regional wall motion (RWM) and ejection fraction (EF) at admission and at discharge were compared between the two groups. Coronary flow velocity variables immediately after primary stenting were compared with changes in left ventriculographic indexes.RESULTSThe change in RWM was significantly greater in the non-ESRF group than it was in the ESRF group (0.9 ± 0.7 vs. −0.1 ± 0.3 standard deviation/chord, respectively, p < 0.001). The change in EF was also significantly greater in the non-ESRF group than it was in the ESRF group (10 ± 10 vs. 1 ± 6%, respectively, p < 0.05). In the non-ESRF group (diastolic to systolic velocity ratio [DSVR] <3.0), the DSVR correlated positively with the change in RWM (r = 0.60, p < 0.005, n = 24) and the change in EF (r = 0.52, p < 0.01).CONCLUSIONSThe coronary flow velocity pattern measured immediately after successful primary stenting is predictive of the recovery of regional and global LV function in patients with AMI.

Prediction of functional recovery in acute myocardial infarction: Comparison between sestamibi reverse redistribution and sestamibi/BMIPP mismatch

Background. It has been known that Tc 99m sestamibi/iodine 123 betamethyliodophenylpentadecanoic ( 123I-BMIPP) (sestamibi/BMIPP) mismatch is an indicator of viable myocardium in acute myocardial infarction (AMI). We have reported that reverse redistribution of sestamibi in AMI indicates the patency of infarct-related artery and a preserved left ventricular function in the chronic stage. In this study we investigated the relationship between reverse redistribution of sestamibi and sestamibi/BMIPP mismatch in patients with AMI. Methods. Twenty-three patients with AMI who received direct percutaneous transluminal coronary angioplasty underwent both BMIPP and sestamibi SPECT within 2 weeks after onset. Sestamibi images were obtained 1 hour (early) and 3 hours (delayed) after injection of sestamibi. BMIPP imaging was carried out 30 minutes after injection. The left ventricle was divided into 17 segments, and regional myocardial uptakes of the tracers in each segment were scored from 0 (normal) to 3 (no activity). A reverse redistribution pattern was defined as an increase of />1 in the regional score at the delayed images. More reduced BMIPP uptake than sestamibi uptake in each segment was determined as sestamibi/BMIPP mismatch. Contrast left ventriculography was performed soon after revascularization and repeated 1 month later. Results. Of 15 patients with sestamibi reverse redistribution, sestamibi/BMIPP mismatch was observed in 14 patients (93%), whereas mismatch was seen in only one of seven patients (14%) without reverse redistribution ( p < 0.01). In patients with sestamibi reverse redistribution, regional scores of BMIPP agreed with those of early and delayed images of sestamibi in 51 segments (46%) and in 92 segments (83%), respectively. In the chronic stage, both regional wall motion and left ventricular ejection fraction improved in patients with sestamibi reverse redistribution (wall motion score: 6.7 ± 2.4 vs 2.7 ± 2.1, p < 0.01; ejection fraction: 56% ± 7% vs 64% ± 8%, p < 0.01), but not in those without reverse redistribution. Conclusion. Both reverse redistribution of sestamibi and sestamibi/BMIPP mismatch reflect the recovery of left ventricular function and thus imply myocardial viability in AMI. Because the presence of reverse redistribution of sestamibi agreed with that of sestamibi/BMIPP mismatch, additional BMIPP images can be replaced by the delayed images after a single injection of sestamibi.

Myocardial contrast versus dobutamine echocardiography as predictors of late functional recovery in acute myocardial infarction treated with primary PTCA

Myocardial contrast versus dobutamine echocardiography as predictors of late functional recovery in acute myocardial infarction treated with primary PTCA

Changes in myocardial metabolism as a diagnostic tool and therapeutic measure

IOCHEMICAL AND metabolic processes form the basis for maintaining functional integrity and cellular viability.‘-” Myocardial metabolism is the important link between myocardial work and perfusion. It is well known that structural abnormalities are preceded by alterations on the biochemical level. The face of modern cardiology and cardiothoracic surgery has drastically changed during the past years; by introduction of invasive procedures allowing insight into dynamic processes of pump function and perfusion, new approaches for salvage and protection of the myocardium have been formulated and tested clinically.4-6 The introduction of interventions for antegrade flow restitution such as thrombolytic therapy, transluminal angioplasty, and acute bypass surgery have significantly enhanced the strategies for myocardial ischemia. One of the determinants is the relationship of the myocardial area-at-risk zone, between ischemically jeopardized, but yet potentially salvageable, territory and the areas of irreversibly damaged myocardium. As shown in animal experiments, myocardial necrosis following coronary occlusion develops from the endocardium and progresses in a waveform transmurally. Clinically, however, a complex situation exists because the acute event is often the result or end-point of longer existing coronary disease with multiple lesions. Collateral flow, vascular tone, and sensitivity to humoral and neurogenic stimuli are quite different. Hypertrophy, heart rate, and wall stress contribute to the significant differences of the extent of an ischemic injury. Therefore, severity and extent of ischemic damage are difficult to predict, even if site and time of occlusion are known. All underlying pathophysiological changes following reperfusion and recovery of acute myocardial infarction are still not completely understood. Generally, parameters of function and pump performance can only describe a complex framework of dynamic sequelae including biochemical, ultrastructural, electrical, and mechanical processes. Nevertheless, concept of prediction for recovery may remain elusive because traditional indices of myocardial viability, such as electrocardiogram (ECG) changes or the extent of wall motion abnormalities, do not always define myocardial viability.4.5,7 In addition, one of the most important challenges in cardiology today is the search for new approaches to the increasing numbers of patients with primary myocardial muscular disease, the cardiomyopathies. Especially in children and in selected forms of cardiomyopathies, proven links to abnormalities of myocardial metabolism have been formulated and therapeutic strategies, such as carnitine replenishment, have been suggested. Changes in myocardial metabolism have been shown to be important in intensive care medicine, and various concepts have been formulated to improve the metabolic patterns in reperfusion or during cardiopulmonary bypass.R

急性心筋梗塞回復期における低負荷トレッドミル運動負荷試験とその有用性に関する研究

To clarify the clinical significance of the exercise test in acute myocardial infarction (AMI), the relationship between the results of exercise test and clinical features was studied. The low level treadmill exercise test (maximum exercise time was 1080 seconds and the maximum oxygen consumption was 7 METs) were performed in 111 patients within 2 months after the onset of AMI. The exercise time, the endpoint of the exercise test, the exercise-induced ST-segment deviation and ventricular premature beats (VPC) were evaluated from the exercise tests. Among the clinical features, age, sex, the severity in the acute period (Killip's classification and Forrester's hemodynamic subset), the findings in cardioangiography (the number of diseased coronary arteries, left ventricular ejection fraction and abnormal wall motion in the left ventricle) and short term prognosis after AMI were evaluated. The prognosis was judged as poor when cardiac death, congestive heart failure, postinfarction angina, the decrease of exercise tolerance and reattack of AMI occurred, or when an aorto-coronary bypass graft or percutaneous transluminal coronary angioplasty was performed. The exercise time was shorter in patients over the age of 60 years (578 +/- 360 seconds) than in younger patients (818 +/- 296 seconds), and also in females (487 +/- 392 seconds) than in males (767 +/- 319 seconds). The patients classed as Forrester's hemodynamic subset IV had shorter exercise time than the others. But, there was no relationship between the exercise time and Killip's classification. Low left ventricular ejection fraction (55% or less) was associated with short exercise time and the apperance of exercise-induced VPC. But the number of diseased coronary artery and abnormal wall motion in the left ventricle were not related to the exercise test. The patients with high exercise tolerance (4.2 METs or more) in the AMI recovery period showed better prognosis than those with low exercise tolerance within one year after AMI (96% vs 50%, p less than 0.0001, respectively). In conclusion, the low level exercise test in AMI was influenced by age, sex and cardiac function, and it was useful in evaluating the short term prognosis after AMI.