Guidelines for training in cardiovascular magnetic resonance (CMR).

These "Guidelines for training in Cardiovascular Magnetic Resonance" were developed by the Certification Committee of the Society for Cardiovascular Magnetic Resonance (SCMR) and approved by the SCMR Board of Trustees.

Survey of the therapeutic approach and efficacy of pentosan polysulfate for the prevention and treatment of equine osteoarthritis in veterinary practice in Australia.

OBJECTIVE: To survey veterinary practitioners in Australia on how they administer pentosan polysulfate (PPS) to horses and their perceptions of the efficacy of PPS for: the prevention and treatment of osteoarthritis (OA), the treatment of OA when PPS is combined with other drugs, and the efficacy of PPS compared with other disease-modifying osteoarthritic drugs. DESIGN: Practitioners were contacted by email, which contained a link to an online survey. RESULTS: A total of 76 responses (34.5%) to the survey were received. Respondents most commonly used PPS as prophylactic therapy prior to competition (80.3%). As a prophylactic agent, PPS was considered by 48.2% of respondents to have high efficacy. The most common dose regimen for prevention and treatment of OA was 3 mg/kg, intramuscularly, once weekly for 4 weeks followed by monthly injections. Most respondents (78%) combined PPS with other drugs for treatment of OA. Intra-articular corticosteroids and hyaluronate (HA) was the most common drug combination used with PPS. PPS was preferred as a prophylactic agent when compared with HA (88.7% vs 11.3%). For treating OA, 83% of respondents considered a combination of PPS, HA and glucosamine to be more efficacious than PPS alone. However, the most common reason not to use this combination was cost (79.1%). CONCLUSION: All respondents used PPS for prophylaxis and/or treatment of OA despite limited published scientific evidence proving its efficacy in horses. Further research is necessary to provide evidence of the clinical efficacy of PPS for the prevention and treatment of OA in horses.

Post-ischaemic myocardial dysfunction (stunning) results from myofibrillar oedema.

OBJECTIVE: To test the hypothesis that myocardial stunning is due to myofibrillar oedema. METHODS: Experiments were performed in anaesthetised closed-chest pigs. In 15 pigs (group 1), myocardial stunning was produced by repetitive ischaemia and reperfusion; 5 pigs each were studied at 2 hours, 2 days, and 5 days later. Circumferential left ventricular (LV) mid-wall myocardial strain (E(cc)) was estimated in vivo using tagged magnetic resonance imaging. Myocardial water content (MWC) was measured post mortem, from which interfilament lattice distance (d) was calculated. In 6 pigs (group 2), myocardial dysfunction was produced by intracoronary administration of a mast cell degranulator. Animals were euthanised immediately upon induction of regional LV dysfunction to avoid development of inflammation. In 4 pigs (group 3), transmission electron microscopy (EM) was performed to quantify d in stunned versus normal myocardium. RESULTS: In group 1 pigs, MWC was raised in the stunned compared with normal myocardium (p<0.02) and decreased over time. An inverse relation was found between E(cc) and MWC in the stunned myocardium (r = -0.81) and between E(cc) and d (r = -0.90). A similar relation was noted between wall thickening and increase in MWC in group 2 (r = -0.84) pigs. In group 3 pigs, d on EM was significantly lower (40 (3) nmol/l) in normal myocardium than in stunned myocardium (46.4 (4) nmol/l), p<0.001. CONCLUSIONS: Ischaemia-reperfusion results in myocardial oedema, with consequent myocyte swelling and myofibrillar oedema. The latter leads to an increase in d, causing myosin heads to either fail to latch, or to latch improperly, onto the actin filament with poor force generation, leading to myocardial dysfunction. As the myocardial oedema abates, myocyte function improves.

The impact of expansive arterial remodeling on clinical presentation in carotid artery disease: a multidetector CT angiography study.

BACKGROUND AND PURPOSE: Atherosclerotic arterial remodeling has been described in the coronary circulation but has not been studied extensively for carotid atherosclerosis. The purpose of our study was to examine the association between carotid artery remodeling and clinical presentation in patients with significant stenosis by using multidetector row CT (MDCT). MATERIALS AND METHODS: One hundred eight patients with >or=50% stenosis (North American Symptomatic Carotid Endarterectomy Trial criteria) by MDCT angiography between January 2004 and June 2006 were identified. The study group included 37 symptomatic (65.9 +/- 13.0 years; 12 women; stenosis, 81.5 +/- 12.2%; 17 with stroke; 15 with transient ischemic attack; 5 with amaurosis fugax) and 71 asymptomatic patients (70.5 +/- 10.5 years; 28 women; stenosis, 78.8 +/- 11.1%). Remodeling ratio (RR) was calculated by dividing the outer vessel circumference at the site of greatest stenosis by a normal reference-segment vessel circumference. Maximum vessel thickness (MxVT) and eccentricity index (EI) of the plaque, defined as maximal thickness/minimal thickness at the site of greatest luminal narrowing, were also determined. Data were analyzed by using an independent t test. RESULTS: The RR was significantly higher in symptomatic patients (1.64 +/- 0.44) than in asymptomatic patients (1.41 +/- 0.5) (P=.02). There was no significant difference in MxVT in symptomatic (5.9 +/- 2.1 mm) and asymptomatic patients (5.6 +/- 2.4 mm) (P=.45) and no significant difference in EI (symptomatic, 4.7 +/- 2.7; asymptomatic, 4.3 +/- 2.2; P=.38). CONCLUSION: In this series of subjects with significant internal carotid artery stenosis, expansive carotid remodeling was significantly greater in patients with cerebral ischemic symptoms than in asymptomatic patients. The extent of expansive remodeling may indicate underlying atherosclerotic plaque vulnerability. MDCT has a role in the evaluation of carotid artery disease beyond examining luminal stenosis.

Tracking myocardial motion from cine DENSE images using spatiotemporal phase unwrapping and temporal fitting.

Displacement encoding with stimulated echoes (DENSE) encodes myocardial tissue displacement into the phase of the MR image. Cine DENSE allows for rapid quantification of myocardial displacement at multiple cardiac phases through the majority of the cardiac cycle. For practical sensitivities to motion, relatively high displacement encoding frequencies are used and phase wrapping typically occurs. In order to obtain absolute measures of displacement, a two-dimensional (2-D) quality-guided phase unwrapping algorithm was adapted to unwrap both spatially and temporally. Both a fully automated algorithm and a faster semi-automated algorithm are proposed. A method for computing the 2-D trajectories of discrete points in the myocardium as they move through the cardiac cycle is introduced. The error in individual displacement measurements is reduced by fitting a time series to sequential displacement measurements along each trajectory. This improvement is in turn reflected in strain maps, which are derived directly from the trajectories. These methods were validated both in vivo and on a rotating phantom. Further measurements were made to optimize the displacement encoding frequency and to estimate the baseline strain noise both on the phantom and in vivo. The fully automated phase unwrapping algorithm was successful for 767 out of 800 images (95.9%), and the semi-automated algorithm was successful for 786 out of 800 images (98.3%). The accuracy of the tracking algorithm for typical cardiac displacements on a rotating phantom is 0.24 +/- 0.15 mm. The optimal displacement encoding frequency is in the region of 0.1 cycles/mm, and, for 2 scans of 17-s duration, the strain noise after temporal fitting was estimated to be 2.5 +/- 3.0% at end-diastole, 3.1 +/- 3.1% at end-systole, and 5.3 +/- 5.0% in mid-diastole. The improvement in intra-myocardial strain measurements due to temporal fitting is apparent in strain histograms, and also in identifying regions of dysfunctional myocardium in studies of patients with infarcts.

Age-associated changes in regional aortic pulse wave velocity.

OBJECTIVES: This study was designed to determine noninvasively the age-associated changes in regional mechanical properties in normals using phase-contrast magnetic resonance imaging (PCMRI). BACKGROUND: It has been well documented that there is a progressive increase in aortic pulse wave velocity (PWV) with age. Previously, PWV has been measured at a single aortic location, or has compared arterial waves between carotid and femoral points to determine PWV. METHODS: Applanation tonometry (TONO) and in-plane PCMR was performed in 24 volunteers (12 men) ranging in age from 21 to 72 years old. The PCMRI PWV was measured in three aortic segments. As validation, TONO was performed to determine PWV between the carotid and femoral artery. RESULTS: When PCMRI PWV was averaged over the three locations, it was not different from TONO (7.9 +/- 2.3 vs. 7.6 +/- 2.4 m/s, respectively). When the volunteers were divided into groups of < 55 and > or =55 years old, the younger group showed similar PWV at each aortic location. However, the older group displayed significantly increased PWV in the region spanning the ascending and proximal descending aorta compared with the mid-thoracic or abdominal segments (10.6 +/- 2.5 m/s, 9.2 +/- 2.8 m/s, and 7.1 +/- 1.7 m/s, respectively, p < 0.001, analysis of variance). CONCLUSIONS: In-plane PCMRI permits determination of PWV in multiple aortic locations in a single acquisition. Progressive fragmentation of elastic fibers and alterations in the regulation of vascular tone may result in an age-related, regional increase in PWV primarily affecting the proximal aorta.

Combined angiotensin converting enzyme inhibition and angiotensin AT(1) receptor blockade up-regulates myocardial AT(2) receptors in remodeled myocardium post-infarction.

OBJECTIVES: In an ovine model of left ventricular (LV) remodeling after transmural anteroapical myocardial infarction (MI), we have previously demonstrated that the combination of angiotensin converting enzyme (ACE) inhibition and AT(1) receptor blockade is more effective at limiting LV remodeling than either therapy alone. We hypothesized that the beneficial effect of combined therapy is due in part to upregulation of AT(2) receptor levels. METHODS: Two days after transmural anteroapical MI by coronary ligation, 16 sheep were randomized to losartan (50 mg/day), ramipril (10 mg/day), ramipril+losartan (combined therapy), or no therapy. At 8 weeks after MI, radioligand receptor assay were deployed with homogenates from regional LV tissues. RESULTS: We found that AT receptors in normal sheep myocardium are predominantly of the AT(2) receptor subtype. Binding studies of remodeled myocardium 8 weeks later showed that the apparent maximum binding (B(max)) was increased from 23 to 48 fmol/mg protein only in animals with combined therapy. The AT(2)/AT(1) proportion was increased significantly in animals with combined therapy compared to infarcted controls (18.0 vs. 5.17). CONCLUSIONS: These results indicate that AT(2) receptor expression increased significantly during LV remodeling with combined therapy but not with either therapy alone. In combination with prior work demonstrating the effectiveness of combined therapy in limiting LV remodeling, this study is consistent with the hypothesis that AT(2) receptors play a cardioprotective role in LV remodeling after MI.

Combined angiotensin II receptor antagonism and angiotensin-converting enzyme inhibition further attenuates postinfarction left ventricular remodeling.

BACKGROUND: ACE inhibition (ACEI) attenuates post-myocardial infarction (MI) LV remodeling, but the effects of angiotensin II type 1 receptor (AT(1)) antagonism alone or in combination with ACEI are unclear. Accordingly, we investigated the effects of AT(1) antagonism, ACEI, and their combination in a well-characterized ovine postinfarction model. METHODS AND RESULTS: Beginning 2 days after transmural anteroapical MI, 62 sheep were treated with 1 of 5 treatment regimens: no therapy (control, n=12), standard-dose ACEI (sACEI; ramipril 10 mg/d, n=14), high-dose ACEI (hACEI; ramipril 20 mg/d, n=8), AT(1) blockade (losartan 50 mg/d, n=13), and combination therapy with sACEI+AT(1) blockade (CT; ramipril 10 mg/d+losartan 50 mg/d, n=15). MRI was performed before and 8 weeks after MI to quantify changes in LV end-diastolic and end-systolic volume indices (DeltaEDVI, DeltaESVI) and ejection fraction (DeltaEF). Change in regional percent intramyocardial circumferential shortening in noninfarcted segments adjacent to the infarct (Adj Delta%S) was measured by tagged MRI. CT resulted in the most marked blunting of LV remodeling: DeltaESVI (+1.0+/-0.4, +0.7+/-0.4, +0.6+/-0.3, +0.9+/-0.5, and +0.4+/-0.2* mL/kg); DeltaEDVI (+0.9+/-0.4, +0.7+/-0.5, +0.6+/-0.5, +0.9+/-0.5, and +0.4+/-0.3 mL/kg); DeltaEF (-24+/-7, -18+/-6, -14+/-7, -18+/-10, and -11+/-9* %); and Adj Delta%S (-8+/-4, -7+/-3, -5+/-3, -5+/-3, and -2+/-3* %) for Control, sACEI, hACEI, AT(1) blockade, and CT, respectively (*P<0.04 versus sACEI, AT(1) blockade, and control; P<0.05 versus control; P<0.002 versus AT(1) blockade and control). EDVI and ESVI at 8 weeks after MI were smallest with CT (P<0.02 versus all). CONCLUSIONS: Combination therapy with sACEI+AT(1) blockade shows promise in attenuating postinfarction LV remodeling but was not clearly superior to hACEI in the present study.

Regional myocardial strain before and after mitral valve repair for severe mitral regurgitation.

Magnetic resonance tagging (MRI) can be used to study intramyocardial trains in human in vivo. We wished to determine whether patients with severe mitral regurgitation demonstrate subtle myocardial contractile dysfunction despite normal left ventricular (LV) ejection fraction (EF) and how, mitral valve repair (MVR) may preserve EF in such patients. MRI was performed on seven patients with severe mitral regurgitation (mean age +/- SD, 65+/-13 years) and normal EF day 1 (range, 0-8 days) before (Pre) and week 8+/-3 after (Post) MVR and on nine normal volunteers (mean age, 32+/-4). LV mass index (LVMI), end-diastolic and end systolic volume, mass/volume ratio, EF, and sphericity index were measured Pre and Post. Two-dimensional strain analysis of MR tagged images was performed and expressed as L1 (greatest systolic lengthening, radial in normal subjects), L2 (greatest systolic shortening, circumferential in normals), and beta (angular deviation of L1 from the radial direction). LVMI fell from 142+/-38 g/m2 Pre to 117+/-44 g/m2 Post (p < or = 0.008) as did LV end-diastolic volume (117+/-26 to 69+/-12 ml, p < or = 0.003), whereas EF remained unchanged (59+/-7% at both time points). LV mass/volume ratio increasedfrom 2.2+/-0.3 g/ml Pre to 3.1+/-0.4 g/ml Post (p < or = 0.02) and sphericity index fell from 0.86+/-0.10 to 0.71+/-0.13 (p = 0.02). In the short axis, L1 was greater in patients with mitral regurgitation than normal subjects (19+/-9% vs 16+/-6%, p < or = 0.003) and tended to increase further after MVR (21+/-8%, p < or = 0.06 vs. Pre). Beta was abnormal in mitral regurgitation (19+/-8 vs. 12+/-8 degrees in control subjects, p < 0.0001) and remained abnormal after MVR (19+/-9 degrees). L2 in the short axis was depressed in mitral regurgitation compared with control subjects (12+/-6% vs. 21+/-6%, p < or = 0.001) and was further depressed after MVR (9+/-7%, p < 0.001 vs. Pre). As detected by MRI, regional myocardial strains are abnormal in severe mitral regurgitation despite normal EF, characterized by increased short-axis systolic lengthening that is abnormally directed and by reduced shortening. After MVR, the further increase in short-axis lengthening may preserve EF despite its abnormal direction and a fall in shortening. The increase in short-axis lengthening may be due in part to the reduction in LV sphericity after MVR.

Contractile reserve and contrast uptake pattern by magnetic resonance imaging and functional recovery after reperfused myocardial infarction.

OBJECTIVES: We hypothesized that contrast-enhanced and dobutamine tagged magnetic resonance imaging (MRI) could investigate microvascular integrity and contractile reserve of reperfused myocardial infarction (MI) in one examination. BACKGROUND: In reperfused MI, microvascular integrity and contractile reserve are important determinants of functional recovery. METHODS: Twenty-three patients with a reperfused first MI were studied. On day 3+/-1 after MI, patients underwent tagged MRI at baseline and during infusion of 5 and 10 microg/kg/min of dobutamine followed by contrast-enhanced MRI (first pass and delayed imaging) after a bolus infusion of gadolinium-diethylenetriaminepenta-acetic acid. Tagged MRI was performed 9+/-1 weeks later (follow-up). Eighty-four transmural regions with hyperenhancement on delayed contrast-enhanced images were defined as COMB (first pass hypoenhancement) or HYPER (normal first pass signal enhancement). Percent circumferential segment shortening was measured within the subendocardium and subepicardum of each region of HYPER or COMB at baseline, peak dobutamine and follow-up. RESULTS: Shortening improved in COMB regions from 4+/-1% at baseline to 10+/-1% at peak dobutamine and 10+/-1% at follow-up, respectively (p<0.0003 vs. baseline for both). The HYPER regions likewise improved from 10+/-1% at baseline to 16+/-1% and 17+/-1%, respectively (p<0.0004 vs. baseline for both). Function within COMB regions was less than that of HYPER at baseline, peak dobutamine and follow-up (p<0.0003 for all). CONCLUSIONS: Dobutamine magnetic resonance tagging and contrast enhanced MRI are complementary in assessing functional recovery after reperfused MI. Regions of delayed contrast hyperenhancement demonstrate both contractile reserve and late functional recovery. However, if these regions demonstrate first pass contrast hypoenhancement, they are associated with greater myocardial damage.

Increase in glycocalicin levels in platelet concentrates stored in plasma or synthetic medium for 8 days: comparison with other platelet activation markers.

BACKGROUND AND OBJECTIVES: Glycocalicin (GC) is a proteolytic fragment of GpIb and can conveniently be measured in supernatants of platelet concentrates (PCs) by means of a sandwich ELISA. Because of the convenience of the assay and easy sample storage, we tested its suitability as a sensitive platelet activation parameter during PC storage. MATERIAL AND METHODS: Filtered PCs in plasma or additive solution were made from 5 pooled buffy coats and were subsequently stored during 8 days at 22+/-2 degrees C. Correlation coefficients (r) were calculated after comparison of GC levels with platelet parameters. RESULTS: A significant increase in GC concentration was found on all subsequent sampling days. PC stored in plasma showed GC levels that correlated well with the soluble P-selectin levels (r = 0.7506), P-selectin (CD62P) expression on platelet membranes (r = 0. 8843), morphology scores according to Kunicki (r = -0.7102), lactate concentrations (r = 0.9216), glucose concentrations (r = -0.8913) and beta-thromboglobulin (beta-TG) concentrations (r = 0.8913). In PCs stored in additive solution, the correlation coefficients with these markers were 0.9209 with soluble P-selectin, 0.7161 with CD62P expression, -0.7474 with morphology score, -0.8908 with glucose concentrations, 0.8923 with lactate concentrations and 0.8908 with beta-TG concentrations. CONCLUSIONS: The GC concentration correlates well with sensitive platelet (activation) parameters, rendering it a sensitive and convenient parameter for platelet activation.

Effect of general anesthesia on the severity of mitral regurgitation by transesophageal echocardiography.

The effect of general anesthesia on the severity of mitral regurgitation (MR) was examined in 43 patients with moderate or severe MR who underwent preoperative and intraoperative transesophageal echocardiography. Systolic blood pressure, mean arterial pressure, and left ventricular end-diastolic and end-systolic dimensions were significantly lower during the intraoperative study, reflecting altered loading conditions. The mean color Doppler jet area and mean vena contracta decreased and the mean pulmonary venous flow pattern changed from reversed to blunted, reflecting a significant reduction in the severity of MR. Overall, 22 of the 43 patients (51%) improved at least 1 MR severity grade when assessed under general anesthesia. Thus, intraoperative transesophageal echocardiography may significantly underestimate the severity of MR. A thorough preoperative assessment is preferable when deciding whether to perform mitral valve surgery.

Characterization of signal properties in atherosclerotic plaque components by intravascular MRI.

Magnetic resonance imaging (MRI) is capable of distinguishing between atherosclerotic plaque components solely on the basis of biochemical differences. However, to date, the majority of plaque characterization has been performed by using high-field strength units or special coils, which are not clinically applicable. Thus, the purpose of the present study was to evaluate MRI properties in histologically verified plaque components in excised human carotid endarterectomy specimens with the use of a 5F catheter-based imaging coil, standard acquisition software, and a clinical scanner operating at 0.5 T. Human carotid endarterectomy specimens from 17 patients were imaged at 37 degrees C by use of an opposed solenoid intravascular radiofrequency coil integrated into a 5F double-lumen catheter interfaced to a 0.5-T General Electric interventional scanner. Cross-sectional intravascular MRI (156x250 microm in-plane resolution) that used different imaging parameters permitted the calculation of absolute T1and T2, the magnetization transfer contrast ratio, the magnitude of regional signal loss associated with an inversion recovery sequence (inversion ratio), and regional signal loss in gradient echo (gradient echo-to-spin echo ratio) in plaque components. Histological staining included hematoxylin and eosin, Masson's trichrome, Kossa, oil red O, and Gomori's iron stain. X-ray micrographs were also used to identify regions of calcium. Seven plaque components were evaluated: fibrous cap, smooth muscle cells, organizing thrombus, fresh thrombus, lipid, edema, and calcium. The magnetization transfer contrast ratio was significantly less in the fibrous cap (0.62+/-13) than in all other components (P<0.05) The inversion ratio was greater in lipid (0.91+/-0.09) than all other components (P<0.05). Calcium was best distinguished by using the gradient echo-to-spin echo ratio, which was lower in calcium (0.36+/-0.2) than in all plaque components, except for the organizing thrombus (P<0.04). Absolute T1 (range 300+/-140 ms for lipid to 630+/-321 ms for calcium) and T2 (range 40+/-12 ms for fresh thrombus to 59+/-21 ms for smooth muscle cells) were not significantly different between groups. In vitro intravascular MRI with catheter-based coils and standard software permits sufficient spatial resolution to visualize major plaque components. Pulse sequences that take advantage of differences in biochemical structure of individual plaque components show quantitative differences in signal properties between fibrous cap, lipid, and calcium. Therefore, catheter-based imaging coils may have the potential to identify and characterize those intraplaque components associated with plaque stability by use of existing whole-body scanners.

Pulmonary embolism complicated by patent foramen ovale and paradoxical embolization.

We present the case of a 74-year-old male with chest pain, dyspnea, and syncope secondary to an acute pulmonary embolism complicated by a patent foramen ovale with straddling thrombus and paradoxical embolization. We review the literature with specific focus on the pathogenesis and acute treatment of this life-threatening occurrence.

Current and future applications of cardiovascular magnetic resonance imaging.

Magnetic resonance imaging (MRI) is one of the newest and most exciting imaging techniques for the cardiovascular system. Its present clear-cut clinical indications include the diagnosis of pericardial disease, aortic disease, cardiac masses, congenital heart disease, anomalous coronary arteries, and right ventricular dysplasia. However, the indications for cardiovascular MRI are growing as its spatial resolution and versatility is increasingly acknowledged. MRI is now recognized as the gold standard measure of left ventricular size and global and regional function. Valvular function can be interrogated in a straightforward fashion. Indications that are now available in some institutions and will be more widespread in the near future include magnetic resonance dobutamine stress testing and magnetic resonance perfusion imaging with or without vasodilator stress. Coronary artery imaging for diagnosis of the severity of disease remains in development, as does imaging of coronary flow and flow reserve. Other exciting applications currently being investigated include real-time imaging and intravascular MRI, enabling imaging from the inside of vessels outward, thereby enhancing the ability to image atherosclerotic plaque. The applications of MRI to the cardiovascular system are rapidly expanding and will continue to do so in the new millennium.

Global alterations in mechanical function in healed reperfused first anterior myocardial infarction.

Two-dimensional analysis techniques were applied to breathhold magnetic resonance (MR) tagged images in humans to better understand left ventricular (LV) mechanics 8 weeks after large reperfused first anterior myocardial infarction (MI). Eighteen patients (aged 51 +/- 13 yr, 15 men) were studied 8 +/- 1 weeks after first anterior MI as were 9 volunteers, (aged 30 +/- 3, 7 men). Breathhold MR myocardial tagging was performed with short-axis images spanning the LV from apex to base. Myocardial deformation was analyzed from apical, mid-LV, and basal slices using two-dimensional analytic techniques and expressed as L1 (greatest systolic lengthening), L2 (greatest systolic shortening), and beta (angular deviation of L1 from the radial direction). LV ejection fraction (EF) by MR imaging in the patients after MI was 45 +/- 15%. The apex and midventricle in patients demonstrated reduced L1 and L2 and increased beta compared with normal subjects with the greatest abnormalities at the apex, as expected in anterior infarction. However, in addition, basal L1 was lower than normal subjects (10 +/- 6% versus 19 +/- 7%, p < 0.0001) as was L2 (14 +/- 7% versus 17 +/- 6%, p < 0.04). Beta was greater than normal at the base (23 +/- 20 degrees and 14 +/- 10 degrees, p < 0.02). L2 correlated significantly with EF in the patient group (EF = 2.6 x L2 + 7, r = 0.68, p < 0.002). After healing of reperfused first anterior MI, maximal lengthening and maximal shortening and the orientation of maximal strains are abnormal throughout the left ventricle, including mild abnormalities at the base. This suggests more diffuse abnormalities in regional mechanical function than simply within the zone of healed infarction.

Absence of adverse outcomes after magnetic resonance imaging early after stent placement for acute myocardial infarction: a preliminary study.

Previous studies have documented the safety of magnetic resonance imaging (MRI) of stents in vitro, when placed in animals in vivo, and in patients after elective stent placement. The safety of imaging patients' with stents early after myocardial infarction (MI) has not been examined. We studied 13 patients in an MRI study of myocardial viability on day 3 +/- 1 after stent placement for acute MI. No patient had any clinical events in the early post-MI period, and only 1 of 13 patients demonstrated in-stent restenosis with a mean follow-up of 7 +/- 2 months. For comparison, a group of 17 patients studied concurrently at Allegheny General Hospital as part of the Stent PAMI study, without undergoing MRI, suffered two early deaths and three episodes of in-stent restenosis within 6 months. Based on a review of the literature and this preliminary study, recent stent placement for acute MI should not be considered a contraindication to MRI.

Beta-blockade improves adjacent regional sympathetic innervation during postinfarction remodeling.

The effect of beta-blockade on left ventricular (LV) remodeling, when added to angiotensin-converting enzyme inhibition (ACEI) after anterior myocardial infarction (MI), is incompletely understood. On day 2 after coronary ligation-induced anteroapical infarction, 17 sheep were randomized to ramipril (ACEI, n = 8) or ramipril and metoprolol (ACEI-beta, n = 9). Magnetic resonance imaging was performed before and 8 wk after MI to measure changes in LV end-diastolic, end-systolic, and stroke volume indexes, LV mass index, ejection fraction (EF), and regional percent intramyocardial circumferential shortening. (123)I-labeled m-iodobenzylguanidine (MIBG) and fluorescent microspheres before and after adenosine were infused before death at 8 wk post-MI for quantitation of sympathetic innervation, blood flow, and blood flow reserve in adjacent and remote noninfarcted regions. Infarct size, regional blood flow, blood flow reserve, and the increase in LV mass and LV end-diastolic and end-systolic volume indexes were similar between groups. However, EF fell less over the 8-wk study period in the ACEI-beta group (-13 +/- 11 vs. -22 +/- 4% in ACEI, P < 0.05). The ratio of adjacent to remote region (123)I-MIBG uptake was greater in ACEI-beta animals than in the ACEI group (0.93 +/- 0.06 vs. 0.86 +/- 0.07, P < 0.04). When added to ACE inhibition after transmural anteroapical MI, beta-blockade improves EF and adjacent regional sympathetic innervation but does not alter LV size.