Role of pre-infarction angina and inflammatory status in the extent of microvascular obstruction detected by MRI in myocardial infarction patients treated by PCI.

BACKGROUND/OBJECTIVES: The extent of microvascular obstruction (MVO) during myocardial infarction referred to as the "no-reflow phenomenon", may determine myocardial damage. Our study aimed to investigate the incidence and the influencing factors of MVO in patients with ST-elevation myocardial infarction (STEMI) treated by primary percutaneous intervention (PCI). PATIENTS, METHODS: Using contrast-enhanced MRI, microvascular obstruction was defined as early hypoenhancement. Contrast defects were scored from 0 (no hypoenhancement) to 3 (strong hypoenhancement). 50 patients (56+/-11 years) with STEMI underwent PCI. Contrast-enhanced MRI (6+/-2 days after STEMI) and biochemical parameters were evaluated. RESULTS: Microvascular obstruction (score 1 to 3) was observed in 90% of the patients and major microvascular obstruction (score 2-3) in 54%. In univariate analysis, leukocytes and CRP levels were associated with MVO, whereas pre-infarction angina and prior medication by aspirin or calcium channel antagonist appeared protective. Microvascular obstruction intensity positively correlated with baseline inflammation status assessed by C-reactive protein and leukocytes (rho=0.43 and rho=0.44; p=0.003), the peak of CK (rho=0.56; p=0.01) or Troponin I (rho=0.59; p=0.01) and negatively correlated with LVEF (rho=-0.44; p=0.002). Multivariate analysis identified the absence of pre-infarction angina as the only independent predictor for microvascular obstruction (odds ratio, 8.35, 95% confidence interval 1.27-54.71; p=0.027). CONCLUSION: MRI-detected microvascular obstruction has a high incidence in patients with STEMI treated by primary PCI and determines post-MI LVEF even in patients with post PCI TIMI 3 flow score. Pre-infarction angina appears to be an independent determinant of the extent of MVO detected by MRI.

Myocardial flow reserve parametric map, assessed by first-pass MRI compartmental analysis at the chronic stage of infarction.

Regional myocardial flow and flow reserve (MFR) were assessed by compartmental analysis of Gd-enhanced MRI first-pass data in 7 patients with atypical chest pain, and in 15 patients with previous transmural myocardial infarction. The FE product (Flow x Extraction coefficient), derived from the modified Kety equation, was measured in regions corresponding to the Tetrofosmine-SPECT fixed defect and in remote normal regions. The FE product at rest and hyperemic FE product were similar in healed revascularized tissues (70.5 +/- 15.6 and 112.5 +/- 19.5 ml/mn/100 g, respectively) and in normal myocardium (76.2 +/- 18.3 and 142.2 +/- 33.0, respectively). In contrast, the FE index (48.8 +/- 15.2 and 60.7 +/- 18.0, respectively, P < 0.01 versus the two previous groups) and the MFR (1.27 +/- 0.20 vs. 1.91 +/- 0.29 in normal regions) were reduced in healed fibrotic tissues when the infarct-related artery remained occluded. Myocardial flow reserve maps allowed correct identification of regions corresponding to an occluded infarct-related artery.

[Cartography of absolute myocardial perfusion with magnetic resonance imaging. Methods and results]. / Cartographie de la perfusion myocardique absolue avec imagerie par résonance magnétique. Méthodes et résultats.

Ultra-rapid dynamic MRI (one image per heart beat) can follow the progression of the intra-myocardial signal during the first passage of diffusable gadolinium chelates injected as a bolus through a peripheral vein. A quantitative evaluation of myocardial perfusion is possible using a compartmental model of analysis. Absolute myocardial flow can be measured at rest and during hyperaemia induced by dipyridamole. It is possible to associate functional mapping, corresponding to parametric images of the flow indices, to the global evaluation. The ratio between the values obtained during hyperaemia and under basal conditions correspond to the myocardial reserve. The principles, results and limitations of this method are discussed in the light of published results, underlining the advantages of absolute flow measurement and of the differences between the results of MRI and myocardial scintigraphy.

[MRI semeiology of segmental contraction abnormalities in arrhythmogenic dysplasia of the right ventricle]. / Séméiologie IRM des anomalies de la contraction segmentaire dans la dysplasie arythmogène du ventricule droit.

The diagnosis of localized arrhythmogenic right ventricular dysplasia may be difficult to ascertain. Aside from electrophysiological arguments, visualization of an abnormal right ventricular contraction pattern is of crucial importance for diagnosis. Cine-MR is almost the only examination method which offers detailed informations on the right ventricular contraction pattern. Nine observations of segmental right ventricular contraction abnormalities assessed by cine-MR are described here: dyskinesia of the distal part of the anterior wall (2), of the inferior wall (2), of the right ventricular outflow tract (2); akinesia of the outflow tract (2) and of the inferior wall (1). Morphological abnormalities of the right ventricle are always associated with contraction abnormalities but seem to be less disease specific. Patients should be more readily referred for a cine-MR examination when the diagnosis of localized right ventricular dysplasia is suspected. Cine-MR sequences related to these observations may be reached via Internet at:http:@alsace.u-strasbg.fr/cardio/coeur.htm.

Comparison between abnormalities in segmental endocardial motion and abnormalities in segmental wall thickening after anterior myocardial infarction. A cine-magnetic resonance study.

In this study, two patterns of regional contract on of the left ventricle have been studied: endocardial motion and wall thickening, in order to check which of these was the most affected after myocardial infarction. The clinical relevance of this comparison was to assess which parameter of the regional contraction abnormality would best depict the severity of the infarction. Long axis cine-magnetic resonance slices were used to assess segmental systolic left ventricular endocardial motion and segmental systolic wall thickening in 39 normal subjects and in 30 patients at the chronic stage of an anterior myocardial infarction. In the group of normal subjects, endocardial motion and wall thickening showed significant regional heterogeneity. Overall endocardial motion was greater than overall wall thickening: 9.5 +/- 2.0 mm vs 7.1 +/- 1.8 mm. P = 4 x 10(-12) (3.1 +/- 1.2 mm vs 2.0 +/- 0.7 mm, P = 9 x 10(-5) after infarction). A significant linear correlation was found between these two parameters. In the infarction group, abnormality scores for endocardial motion and for wall thickening were calculated. These scores were defined as the average values exceeding the mean minus two standard deviations of the normal range for segments corresponding to the antero-septal-apical walls. The abnormality score for endocardial motion greater than the abnormality score for wall thickening: 0.31 +/- 0.12 vs 0.20 +/- 0.07, P = 9 x 10(-4). We conclude that, in clinical practice, endocardial motion is affected to a greater degree by myocardial infarction than is wall thickening and therefore constitutes a more discriminant index in the assessment of post-infarction patients.

Recanalization of occluded superficial femoral arteries using the rotational transluminal angioplasty catheter system (ROTACS).

A total of 85 occluded superficial femoral arteries were treated using the rotational transluminal angioplasty catheter system (ROTACS). The mean length of the occlusions was 7cm; 76% were uncalcified or only slightly calcified whereas 24% were calcified or highly calcified. The mean preoperative ankle:brachial index was 0.51. Primary success was achieved in 62 of 85 cases (73%). The mean length of reperfused occlusions was 6.2 cm: 26% of these lesions were calcified. The mean ankle:brachial index was 0.91. There were 23 primary failures (27%): reperfusion was impossible in 11 cases (including one complicated by perforation) and there were eight dissections, three cases where residual stenosis exceeded 50%, and one other unspecified failure. The mean length of these occlusions was 10.5 cm; 17% were calcified. Two patients developed a distal embolus and one died 10 days after reperfusion. The probability of primary patency of a reperfused artery was 44% at 1 year. Forty-two of the 62 patients who achieved primary success remained symptom free; the mean length of the original occlusion was 4.5 cm. Fifteen patients developed a new area of stenosis whereas five others exhibited new occlusion after a mean interval of 6 months. The mean length of these reperfused arteries was 9 cm. The probability of secondary patency at 1 year was 58%. Arterial calcification did not appear to influence the feasibility of reperfusion using the catheter. The main factor determining successful reperfusion was the length of the occlusal defect (P < 0.05). Reperfusion using the ROTACS did not improve the feasibility of reperfusion by conventional transluminal angioplasty.(ABSTRACT TRUNCATED AT 250 WORDS)

[Rotacs: a device used in coronary and peripheral arterial recanalization]. / Rotacs: un système utilisable dans les désobstructions artérielles coronaires et périphériques.

The authors report their preliminary results with the Rotacs system in the reopening of chronic coronary artery occlusion by low-speed rotational angioplasty. This system improves the percentage of coronary recanalisation in cases where it is impossible to pass the guide wire alone. It seems to be an effective, low-cost complementary tool for the treatment of this type of lesion.

[Accentuation of myocardial ischemia during coronary recanalization in the acute phase of myocardial infarction]. / Accentuation de l'ischémie myocardique contemporaine de la recanalisation coronarienne en phase aiguë d'infarctus du myocarde.

Coronary recanalisation during the acute phase of myocardial infarction, especially by in situ infusion of thrombolytic agents, is accompanied in most cases by rapid regression of chest pain and a reduction in the degree of ST elevation. However, a multicentre retrospective study of 104 attempts at recanalisation, including 78 successful procedures, showed in 10 cases (12.8 p. 100), an apparently paradoxical accentuation of the chest pain with or without increased ST elevation, at the time of angiographically demonstrable recanalisation. This phenomenon may be interpreted as being the result of aggravation of the ischaemia of the border zone, the objective of therapy. Several pathogenic hypotheses, all with experimental proof, may be suggested to explain these observations (haemorrhagic infarction, non reperfusion, ischaemic contraction due to massive intracellular flow of calcium, etc.). It is usually associated with arrhythmias and may be considered to be a reliable sign of recanalisation. It may also explain certain cases of persistence of chest pain and ECG changes despite the demonstration of a permeable epicardial artery on initial coronary angiography.

[Myocardial infarction due to acute right coronary thrombosis. Treatment with in situ fibrinolysis, absence of angiographic residual stenosis]. / Infarctus du myocarde par thrombose aiguë coronarienne droite. Traitement par fibrinolyse in situ, absence de sténose angiographique résiduelle.

The case of a 44 year old patient with inaugural postero-diaphragmatic myocardial infarction is reported. Coronary angiography performed at the 3 rd hour showed total occlusion of the right coronary artery at the level of its second segment. A streptokinase perfusion through a Judkins' catheter positioned in the ostium of the right coronary artery using Rentrop's technique, resulted in recanalisation of the vessel at the 45 th minute. Control coronary angiography on the 10 th day showed an angiographically normal right coronary circulation. The clinical course was complicated by a recurrence on the 12 th day with a new occlusion at the same level. This observation confirms: - the reality of acute coronary thrombosis as a mechanism of myocardial infarction in the absence of significant underlying atherosclerotic stenosis. - the value of early fibrinolytic therapy in situ for limitation of the infarcted myocardial tissues.

[Hemodynamic effects of the association of nifedipine and acebutolol]. / Effets hémodynamiques de l'association nifédipine-acébutolol.

The aim of this study was to assess the effects of the association of sublingual nifedipine and intravenous acebutolol on left ventricular inotropism. A series of 30 randomised patients underwent hemodynamic investigation repeated after a 30 minute interval comprising measurement of left ventricular (LVP) and aortic (AoP) pressures and ventriculography (Vo). Between the two Vo, Group I (N = 10) were given 20 mg sublingual nifedipine (N), Group II (N = 0) were given I mg/Kg acebutolol (A) intravenously in 5 minutes, and Group III (N = 10) the association of 20 mg sublingual N and I mg/Kg intravenous A. All patients had normal resting left ventricular function (ejection fraction greater than 0,55). In Group I, a significant improvement in left ventricular function with reduction of end diastolic pressure, increase ejection fraction, VCF and cardiac index was observed. THese changes were secondary to the reduction in aortic impedence with no effects on the contractile element (assessed by end systolic pressure/end systolic volume - ESP/ESV - ratio). In Group II, a significant reduction in these indices of left ventricular function was recorded secondary to a reduction in contractility. Group III had a special hemodynamic profile comprising: a reduction in afterload identical to that observed in Group I; a significantly greater reduction in the ESP/ESV ratio than in Group II; a greater reduction in the indices of left ventricular function (especially EF, VCF and CI) than in Group II, but the difference was not significant. The data obtained under the conditions of this acute hemodynamic investigation in patients with normal basal left ventricular function may be summarised thus: 1) Nifedipine alone has no detectable negative inotropic effects. 2) The association with acebutolol, nifedipine seems to potentiate myocardial depression (ESP/ESV). 3) This therapeutic association, the value of which has already been demonstrated in coronary insufficiency should be used carefully without precise knowledge of the left ventricular function.