Changes of the left ventricle after myocardial infarction--estimation with cine magnetic resonance imaging during the first six months

Outcome of Impella 2.5 use in patients undergoing Percutaneous Coronary Intervention in Henan, China: a case series

BACKGROUND

Acute myocardial infarction (AMI) complicated by cardiogenic shock (AMI-CS) or heart failure is associated with an unacceptably high in-hospital mortality of 33%-55% and a lost chance to accept PCI (Percutaneous Coronary Intervention).

AIM

The aim of the study was to find out whether percutaneous hemodynamic support device Impella 2.5 improves prognosis of high-risk PCI patients or not.

METHODS

This study was a case series involving six patients who underwent a Left Ventricular Assist Device (LVAD, Impella 2.5, Abiomed, Danvers, MA) implantation after suffering from AMI with a very low ejection fraction and acute heart failure. The clinical experience and outcomes of the patients are hereby discussed.

RESULTS

All PCI procedures were safely completed under LVAD support. The hemodynamic parameters of all patients improved clinically over the next 30 days and following 12 months after Impella insertion except in two patients, of which one patient (Case number 6) died 4 days post-Impella protected PCI procedure due to acute left ventricle heart failure with cardiogenic shock and pulmonary oedema; and another one died at 12 months after Impella protected PCI procedure (Case number 4) due to decompensated heart failure and infected pneumonia.

CONCLUSION

Percutaneous hemodynamic support is favorable and feasible during high risk Percutaneous Coronary Intervention (PCI). A bigger study is needed to substantiate the claims of the current study.

Biomechanics of infarcted left Ventricle-A review of experiments

Myocardial infarction (MI) is one of leading diseases to contribute to annual death rate of 5% in the world. In the past decades, significant work has been devoted to this subject. Biomechanics of infarcted left ventricle (LV) is associated with MI diagnosis, understanding of remodelling, MI micro-structure and biomechanical property characterizations as well as MI therapy design and optimization, but the subject has not been reviewed presently. In the article, biomechanics of infarcted LV was reviewed in terms of experiments achieved in the subject so far. The concerned content includes experimental remodelling, kinematics and kinetics of infarcted LVs. A few important issues were discussed and several essential topics that need to be investigated further were summarized. Microstructure of MI tissue should be observed even carefully and compared between different methods for producing MI scar in the same animal model, and eventually correlated to passive biomechanical property by establishing innovative constitutive laws. More uniaxial or biaxial tensile tests are desirable on MI, border and remote tissues, and viscoelastic property identification should be performed in various time scales. Active contraction experiments on LV wall with MI should be conducted to clarify impaired LV pumping function and supply necessary data to the function modelling. Pressure-volume curves of LV with MI during diastole and systole for the human are also desirable to propose and validate constitutive laws for LV walls with MI.

Effects of cyanidin 3-0-glucoside on cardiac structure and function in an animal model of myocardial infarction

Cyanidin 3-0-glucoside (CG) is a polyphenol with potential health benefits. In this study, we investigated, for the first time, the cardioprotective effects of CG in an animal model of myocardial infarction (MI), a major cause of death worldwide. Sham and MI rats were administered CG (10 mg kg^-1 day^-1) daily for one week prior to surgery, and 8 weeks post-surgery. Echocardiography was performed to assess cardiac structure and function at 4 and 8 weeks. At 4 weeks, MI rats had significantly lower body mass when compared to control rats, and CG administration significantly prevented this decrease. Four-week MI rats also showed significantly increased left ventricle dilation, end systolic and end diastolic volumes in comparison to controls, and CG significantly prevented these adverse changes. Ejection fraction was significantly lower in 4-week MI rats in comparison to controls, and CG had no effect on this parameter. At 8 weeks, body mass was significantly lower in MI rats when compared to control rats, and CG significantly prevented this decrease. At 8 weeks, MI rats showed a significant increase in left ventricle dilation and isovolumic relaxation time, while ejection fraction was significantly lower when compared to controls; these parameters were not altered by CG treatment. Eight-week MI rats had significantly higher level of oxidative stress in heart tissue in comparison to controls, and CG administration did not prevent this increase. In conclusion, administration of CG was able to significantly preserve body mass in both 4 and 8 weeks MI rats, as well as significantly prevent cardiac dilation in 4 weeks MI rats. However, CG was unable to sustain this cardioprotection, as cardiac structure and function were not significantly improved in 8 weeks MI rats.

Time‑dependent and independent effects of thyroid hormone administration following myocardial infarction in rats

Cardiac function is reduced following myocardial infarction (MI) due to myocardial injury and alterations in the viable non-ischemic myocardium, a process known as cardiac remodeling. The current treatments available for patients with acute MI (AMI) reduce infarct size, preserve left ventricular (LV) function and improve survival; however, these treatments do not prevent remodeling, which can lead to heart failure. The aim of the present study was to investigate the effects of thyroid hormone (TH) treatment following MI in an in vivo rat model. A total of 199 rats were separated into 3 groups: Sham operated and 2 different coronary artery ligation (CAL) groups. Rats subjected to CAL were randomly divided into a further 2 groups 24 h following surgery. The first group received standard rat chow (designated the CAL group), while the second group received food containing 0.05% thyroid powder (designated the CALTH group). The mean daily intake of TH per rat was estimated at 3.0 µg T₃ and 12 µg T₄. Echocardiography was used to monitor the rats. Large-scale analysis confirmed the favorable effects of TH treatment following CAL on various parameters of cardiac function. TH treatment reduced LV dilation, and increased global and regional LV function. The development of cardiac hypertrophy was induced and, thus, wall stress was limited. Furthermore, TH treatment improved cardiac geometry, which manifested as an increased sphericity index. Myocardial function, as well as LV dilatation, following CAL and TH treatment was not closely associated with the extent of injury, indicating a novel therapeutic intervention that may alter the course of LV remodeling that typically leads to post-MI heart failure. Data modelling and regressions may be developed to enable the simulation of the pathophysiological processes that occur following MI, and to predict with accuracy the effects of novel or current treatments that act via the modulation of tissue injury, LV dilation, LV geometry and hypertrophy.

Short- and long-term changes in myocardial function, morphology, edema, and infarct mass after ST-segment elevation myocardial infarction evaluated by serial magnetic resonance imaging

BACKGROUND

Knowledge of the natural course after an ST-elevation myocardial infarction (STEMI) treated according to guidelines is limited because comprehensive serial magnetic resonance imaging (MRI) of systolic left ventricular function, edema, perfusion, and infarct size after STEMI has not been undertaken. The aim of this study was to evaluate effects of therapy for STEMI on left ventricular function and perfusion and to test the hypothesis that myocardial perfusion by MRI predicts recovery of left ventricular function.

METHODS

Cine MRI, edema, first-pass perfusion, and late enhancement imaging were performed in 58 patients at day 2 and at 1 and 6 months after successful primary percutaneous coronary stent intervention for STEMI.

RESULTS

Ejection fraction increased 6.3% during the first month (P < .001) and 1.9% from 1 to 6 months (P < .06), indicating a maximal recovery very early after the infarction. The systolic wall thickening in the infarct area almost doubled (P < .001), the perfusion of infarcted myocardium increased approximately 50% (P = .02), and perfusion improved in 72% of patients. Edema decreased with a mean of 2 segments (P < .001) during the first month and another 2.5 segments from 1 to 6 months (P < .001). Infarct size decreased to 1 month (P = .01) and was unchanged from 1 to 6 months (P = .5). Baseline perfusion did not predict improvement in ejection fraction (r = 0.2, P = .2) but did predict regional systolic function (P = .03).

CONCLUSIONS

Left ventricular function, perfusion, and infarct mass recovered substantially after STEMI, with the main part of the change within the first month. First-pass perfusion at rest appeared to predict regional ventricular recovery.

Ventricular arrhythmias: antiadrenergic therapy for the patient with coronary artery disease

Patients who have had a recent myocardial infarction (MI) are at high risk of ventricular arrhythmias that often cause sudden cardiac death. It is believed that sympathetic overactivity in the peri-infarction period may alter the electrophysiology and structure of the myocardium, thus placing these patients at risk of developing rhythm disturbances. A number of pharmacologic and nonpharmacologic therapies have been shown to reduce the risk of post-MI mortality, including sudden cardiac death. beta-Adrenergic blockers are recommended for all post-MI patients without contraindications because of overwhelming clinical evidence of their benefit in reducing mortality in this patient population. Recent clinical trials of implantable cardioverter defibrillators have provided compelling support that they are effective in both the primary and secondary prevention of sudden cardiac death. In addition, several studies have shown that combination therapy with beta-blockers and implantable cardioverter defibrillators have synergistic effects that optimize the benefits of both therapies.

Serial magnetic resonance imaging based assessment of the early effects of an ACE inhibitor on postinfarction left ventricular remodeling in rats

In vivo assessment of treatment efficacy on postinfarct left ventricular (LV) remodeling is crucial for experimental studies. We examined the technical feasibility of serial magnetic resonance imaging (MRI) for monitoring early postinfarct remodeling in rats. MRI studies were performed with a 7-Tesla unit, 1, 3, 8, 15, and 30 days after myocardial infarction (MI) or sham operation, to measure LV mass, volume, and the ejection fraction (EF). Three groups of animals were analyzed: sham-operated rats (n = 6), MI rats receiving lisinopril (n = 11), and MI rats receiving placebo (n = 8). LV dilation occurred on day 3 in both MI groups. LV end-systolic and end-diastolic volumes were significantly lower in lisinopril-treated rats than in placebo-treated rats at days 15 and 30. EF was lower in both MI groups than in the sham group at all time points, and did not differ between the MI groups during follow-up. Less LV hypertrophy was observed in rats receiving lisinopril than in rats receiving placebo at days 15 and 30. We found acceptable within- and between-observer agreement and an excellent correlation between MRI and ex vivo LV mass (r = 0.96; p < 0.001). We demonstrated the ability of MRI to detect the early beneficial impact of angiotensin-converting enzyme (ACE) inhibitors on LV remodeling. Accurate and noninvasive, MRI is the tool of choice to document response to treatment targeting postinfarction LV remodeling in rats.

Cardiac imaging to identify patients at risk for developing heart failure after myocardial infarction

The development of heart failure (HF) after acute myocardial infarction (MI) is recognized as a major complication that leads to a significant increase in morbidity and mortality. Given the availability of effective treatments for improving both quality of life and survival for patients at increased risk for developing HF after MI, early identification of these individuals is critical. Noninvasive cardiac imaging offers a detailed characterization of two important pathophysiological processes related to the development of HF post-MI: left ventricular (LV) remodeling and LV functional recovery. Cardiovascular MRI has recently emerged as the preferred noninvasive imaging modality because of its ability to provide the most comprehensive and informative evaluation of these processes. In addition to allowing for an accurate and reproducible longitudinal follow-up of LV volumes and mass, MRI also offers information on infarct size, the presence of microvascular obstruction, and the transmural extent of infarct scar, all of which are valuable parameters that can assist in identifying patients at risk for developing HF after MI.

Ultrasonic Tissue Characterization Predicts Left Ventricular Remodeling in Patients with Acute Anterior Myocardial Infarction after Primary Coronary Angioplasty

OBJECTIVES

The aim of this study was to assess the role of cyclic variation (CV) of myocardial integrated backscatter (IBS) in the prediction of left ventricular (LV) remodeling in patients with anterior acute myocardial infarction (AMI) after primary coronary angioplasty.

BACKGROUND

Some studies have shown that the CV of myocardial IBS predicts myocardial viability for patients with AMI.

METHODS

We recorded short-axis IBS images within 24 hours of angioplasty in 80 patients with anterior AMI. Two parameters were measured: the magnitude of CV and the normalized time delay (NTD). The increase in LV end-diastolic volume (LVEDV) at 4 weeks (DeltaLVEDV) was defined as LV remodeling (>20% increase from baseline).

RESULTS

Patients were divided into two groups according to LV remodeling status: the remodeling group (n = 41) and the nonremodeling group (n = 39). There was a significant difference in the magnitude of CV between the two groups (5.11 +/- 1.47 vs 5.96 +/- 189 dB, P < .05), and the NTD was significantly different in the two groups (1.57 +/- 0.31 vs 1.23 +/- 0.32, P < .0001). The correlation between the magnitude of CV and DeltaLVEDV was significant but weak (r = -0.338, P < .01). There was significant correlation between NTD and DeltaLVEDV (r = 0.443, P < .0001). Using NTD greater than 1.35 as the optimal cutoff, the sensitivity, specificity, and positive and negative predictive values to predict LV remodeling were 82%, 86%, 87%, and 80%, respectively.

CONCLUSIONS

Myocardial IBS, especially NTD, is useful for predicting LV remodeling in patients with AMI after primary coronary angioplasty.

MR and CT assessment for ischemic cardiac disease

Magnetic resonance imaging and/or contrast-enhanced multidetector computed tomography may be used separately or, often more effectively, in an integrated fashion, to address important issues in patients with coronary artery disease causing ischemic cardiac disease (ICD). These issues include complications of myocardial infarction, such as ventricular dysfunction, myocardial wall rupture, aneurysm formation, intracavitary thrombus, mitral insufficiency, and pericarditis, as well as aspects of planning and monitoring therapy for ICD, such as revascularization and ventricular aneurysm repair.

Intravenous myocardial contrast echocardiography predicts left ventricular remodeling in patients with acute myocardial infarction

BACKGROUND

This study evaluated the ability of intravenous myocardial contrast echocardiography (MCE) performed in the setting of acute myocardial infarction for prediction of left ventricular (LV) remodeling.

METHODS

Intravenous MCE was performed immediately before, 1 hour, and 24 hours after primary percutaneous transluminal coronary angioplasty (PTCA) in 35 patients with a first myocardial infarction. The MCE was used to define the relative perfusion defect size (in %; relMCD). Two-dimensional echocardiography was performed directly after angioplasty and after 4 weeks to determine LV end-diastolic volumes (LVEDV). The increase in LVEDV at 4 weeks defined a remodeling (> 15% increase) and a nonremodeling group (< or = 15% increase).

RESULTS

Patients with remodeling had larger relMCD before (22.0 +/- 16.1 vs 8.0 +/- 11.9, P =.015), 1 hour (20.0 +/- 13.0 vs 4.9 +/- 11.6, P =.001), and 24 hours after PTCA (22.9 +/- 14.1 vs 1.2 +/- 2.8, P <.001). There was a significant correlation between relMCD 24 hours after PTCA and the increase in LVEDV at 4 weeks (r = 0.648; P <.001). Receiver operating characteristic (ROC) curve analysis revealed a relMCD at 24 hours of 5.1% or more to predict remodeling with a sensitivity of 94% and a specificity of 87% (area under ROC curve = 0.917; SE = 0.054). Multivariate analysis demonstrated relMCD at 24 hours to be the only predictor of remodeling (odds ratio = 173.4; P =.022).

CONCLUSION

The size of the persistent MCE perfusion defect after revascularization for acute myocardial infarction has a high predictive value for LV remodeling during a 4-week follow-up period.

Cardiac remodelling in the era of aggressive medical therapy: does it still exist?

AIM

To delineate the natural history of left ventricular remodelling following large anterior myocardial infarction (MI), in the era of aggressive medical therapy.

METHODS

Seventeen selected patients underwent cardiovascular magnetic resonance (CMR) at 2 weeks and 1, 3, 6 and 12 months post infarction.

RESULTS

There was a significant increase in left ventricular (LV) end-diastolic volume index (EDVI) and LV ESVI from 2 weeks to 1 month (P<0.05) but no significant change thereafter. The LV ejection fraction (EF) decreased from 2 weeks to 1 month (P<0.05) and then increased over the year (P=0.02). Throughout the study period the sphericity index increased. There was a significant and progressive decrease in LV mass index over the year, which was associated with a decrease in wall thickness at both the infarct and non-infarct sites. Independent predictors of an early increase in LVESVI were increasing age, increasing CK-MB and not receiving treatment with a statin.

CONCLUSION

This study delineates the natural history of left ventricular remodelling in the modern medical era in those patients who have suffered a large anterior MI. Classical remodelling occurred up to 1 month, but thereafter was attenuated. These findings would suggest that remodelling is not as prevalent in the modern era, and that combined medical management with thrombolysis, ACEi, beta-blockers and statins may strongly influence the development of this remodelling.

Magnetic resonance imaging in coronary heart disease

Modern level of cardiac magnetic resonance imaging (MRI) development already allows its routine use (with proper indications) in coronary heart disease patients for studies of heart morphology and functions, performance of stress tests for evaluation of myocardial perfusion and contractile function. Coronary MRA and some other new MR techniques are close to its wide-scale clinical application. It has been shown that cardiac MRI is a valuable tool for detection of postinfarction scars, aneurysms, pseudoaneurysms, septal defects, mural thrombi and valvular regurgitations. Due to intrinsic advantages of the method it is of special value when these pathological conditions cannot be fully confirmed or excluded with echocardiography. MRI is recognized as the best imaging method for quantification of myocardial thickness, myocardial mass, systolic myocardial thickening, chamber volumes, ejection fraction and other parameters of global and regional systolic and diastolic function. MRI is used in studies of cardiac remodeling in postinfarction patients. The most attractive areas for cardiovascular applications of MRI are assessment of myocardial perfusion and non-invasive coronary angiography. Substantial progress has been achieved in these directions. There are some other new developments in studies of coronary artery disease with MRI. High-resolution MR is used for imaging and quantification of atherosclerotic plaque composition in vivo. Intravascular MR devices suitable for performing imaging-guided balloon angioplasty are created. But before MRI will be widely accepted by the medical community as a important cardiovascular imaging modality several important problems have to be solved. Further technical advances are necessary for clinical implementation of all major diagnostic capabilities of cardiac MRI. The subjective obstacles for growth of clinical applications of cardiac MRI are lack of understanding of its possibilities and benefits both by clinicians and radiologists themselves. So proper training of specialists and promotion of this promising modality among the medical community are necessary.

Changes in left ventricular mass and volumes in patients receiving angiotensin-converting enzyme inhibitor therapy for left ventricular dysfunction after Q-wave myocardial infarction

OBJECTIVES

We evaluated global and segmental left ventricular (LV) mass and LV mass/volume ratio in patients with LV dysfunction receiving angiotensin-converting enzyme (ACE) inhibitor therapy after acute myocardial infarction (MI).

BACKGROUND

ACE inhibitors attenuate LV dilatation and compensatory hypertrophy after acute MI in animal models. However, LV remodeling in patients after acute MI has been largely defined on the basis of changes in chamber volume alone.

METHODS AND RESULTS

Twenty-nine patients with LV ejection fraction <40% received the ACE inhibitor ramipril (range 2.5 to 20 mg/day) within 5 days of their first Q-wave MI. Magnetic resonance imaging was performed at baseline and at 3 months, providing global and regional LV volumes and mass from summated serial short-axis slices. Mean arterial blood pressure was unchanged from baseline to 3-month follow-up (89 +/- 10 to 92 +/- 17 mm Hg). LV mass decreased (90 +/- 25 to 77 +/- 21 gm/m2, p < 0.0005) as LV end-diastolic volumes increased (65 +/- 13 to 73 +/- 22 ml/m2, p < 0.01). Global LV mass to volume ratio decreased from 1.40 +/- 0.28 to 1.08 +/- 0.18 gm/ml (p < 0.0001), as did circumferential wall thickness to volume ratio of noninfarcted myocardium at the base of the LV (0.06 +/- 0.02 to 0.05 +/- 0.02 mm/ml, p < 0.001). LV ejection fraction increased from 35 +/- 6 to 40 +/- 9% (p < 0.001) in the presence of an increase in calculated end-systolic wall stress (185 +/- 57 to 227 +/- 54 gm/cm2, p < 0.01).

CONCLUSIONS

ACE inhibitor therapy was associated with improved LV function in the face of a decrease in mass to volume ratio of the LV as well as a decrease in wall thickness to volume ratio of noninfarcted myocardium. Whether ACE inhibitor therapy had direct or indirect effects on these changes in LV mass and function are open questions that require further investigation.