CNR, G. Monasterio Foundation, Clinical Physiology Institute Pisa

Transcription

1 CNR, G. Monasterio Foundation, Clinical Physiology Institute Pisa Stockholm Aug 29, 2010 Role of MRI in the acute Myocardial Infarction? massimo lombardi

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3 Two days after infarct (top row), the T2 hyperintense area was essentially transmural, and the infarcted region was subendocardial, as delineated by gadolinium delayed enhancement Aletras, A. H. et al. Circulation 2006;113:

4 The area at risk measured by microspheres injected during ischemia correlated with the T2W abnormalities observed 2 days later (R=0.84; top) Aletras, A. H. et al. Circulation 2006;113:

5 17 dogs Aletras AH et Al. Circulation 2006; 113:

6 DE and T2w CMRI Differentiate acute from chronic MI Abdel-Aty, H. et al. Circulation 2004;109: Group A (15 pts) with acute reperfused MI, evaluated 1 day and 6 months later Group B (58 pts) with acute or chronic MI regardless reperfusion or the presence of a previous MI

7 DE and T2w CMRI Differentiate acute from chronic MI Group A (15 pts) with acute reperfused MI, Three patients in group A with anterior infarcts DE T2 T2+ postprocessing STEMI STEMI non-stemi Abdel-Aty, H. et al. Circulation 2004;109:

8 Abdel-Aty, H. et al. Circulation 2004;109: Two chronic MI patients in group B Inferior 6 months old MI Anterior 2.5 months old MI Inferior 3 years old MI

9 Two acute MI patients in group B 4 days old reperfused MI 2.5 days old non reperfused MI Abdel-Aty, H. et al. Circulation 2004;109:

10 Conclusions an approach combining DE and T2- weighted CMR is a clinically reliable tool to differentiate acute from chronic MI. Although DE is a powerful marker of nonviability and therefore detects infarction at any disease stage, transmural high T2 signal accurately identifies the area of the acute event.

11 Edema had: sensitivity (96%), specificity (98%), and accuracy (97%) to differentiate between AMI and CMI. Accuracy of all other imaging findings was lower compared to that of edema (P<0.001). In the presence of infarction on DE, T2w reliably differentiates between AMI and CMI.

12 Right Ventricular Ischemic Injury in Patients with Acute ST-segment Elevation Myocardial Infarction - Characterization with Cardiovascular Magnetic Resonance - PG. Masci, M. Francone, J. Ganame, W. Desmet, Carbone, E. Strata, Siciliano V, G. Todiere, L. Agati, M. Lombardi,S. Janssens, J. Bogaert Circulation in press

13 Background RV infarction is often encountered at autopsy in patients dying of acute myocardial infarction (MI), but the occurrence and impact of RV ischemic injury in patients who survive acute MI is not well known Isner and Roberts 1978 Am J Cardiol Experimental and clinical studies suggested that the right ventricle is likely more resistant to ischemic injury than the left ventricle. In patients with acute STEMI and RV involvement, RV function recovers more rapidly and better than left ventricular (LV) function despite similar initial dysfunction (Bowers NEJM 1994)

14 Study Objective To characterize the pattern of RV ischemic injury in patients with acutely reperfused ST-segment elevation MI by comprehensive CMR study at acute phase and after 4-month follow-up Circulation in press

15 Methods Study population: Three European Centers, 271 consecutive with acute STsegment elevation MI patients (cumulative ST-segment elevation 6 mm) treated by primary PCI within 12 hours from symptoms onset. Exclusion criteria: a) prior MI or revascularization b) atrial fibrillation; c) cardiogenic shock, d) renal failure (plasma creatinine> 2 mg/dl); e) contraindication to CMR; e) any known clinical condition that might affect RV function (severe chronic obstructive or restrictive pulmonary disease, primary pulmonary hypertension, congenital heart disease, moderate-to-severe valvular heart disease). Circulation in press

16 Methods Comprehensive CMR Infarct-related myocardial edema by T2-weigheted CMR Cine Imaging MI size quantification by ( LGE ) late gadolinium enhancement

17 Results 51% 49% 60% 34% Circulation in press

18 Results RV Ischemic Injury Relationship with Infarct Location 113 pts (47%) with inferior LV MI 13 pts (5%) laterallv MI 116 pts (48%) with anterior LV MI 85 pts (75%) with RV ME No RV ME nor LGE 38 pts (33%) with RV ME 61 pts (54%) with acute RV LGE 13 pts (11%) with acute RV LGE

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20 Conclusion 1) Temporary RV dysfunction is frequently present early post-infarction, and is primarily determined by RV ischemic involvement. 2) Although the right ventricle is preferentially involved in inferior LV infarcts, it is not uncommon to find similar, albeit less extensive abnormalities, in anterior LV MI as well. 3) The reduction in frequency and size of RV LGE at follow-up along with excellent functional recovery indicate that right ventricle is more resistant to ischemic injury than the left one. Accordingly, early post-infarction RV enhancement may be an epiphenomenon of extensive edema, and not necessarily be synonymous of myocardial necrosis 4) Persistent RV LGE occurs in a minority of patients, most likely representing postinfarction myocardial scarring, and is associated with adverse RV remodeling and worse function.

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22 Background Comprehensive CMR study in ST-segment elevation MI Determination of the AAR extent by T2-w STIR imaging MI size quantification by ( LGE ) late gadolinium enhancement Myocardial Salvage JACC Cardiov. Imaging, 2010

23 Aim To investigate the clinical value of CMR-derived myocardial salvage by testing its association with two important clinical and prognostic parameters: left ventricular (LV) remodeling and early ST-segment resolution JACC Cardiov. Imaging, 2010

24 Methods Between May 2006 and September pts at G.Monaterio Foundation, ( IT ) Pisa 82 pts at Gasthuisberg University Hospital, ( BE ) Belgium 137 consecutive patients (61±12 years; 111 male) with acute ST-segment elevation MI treated by PCI within 12-hour from symptoms onset were prospectively studied Exclusion criteria: critical stenosis ( 75%) in any vessel other than the infarct-related artery; prior MI or revascularization; cardiogenic shock; renal insufficiency; atrial fibrillation; CMR contraindications JACC Cardiov. Imaging, 2010

25 Methods Study protocol ( 1-week CMR study (acute phase, Scout imaging T2-w STIR imaging Cine imaging LGE imaging ( mmol/kg Gadodiamide (0.2 ( 1-week 12-lead ECG (acute phase, ( 2 1 hour after PCI (ECG ( 1 At hospital admission (ECG JACC Cardiov. Imaging, 2010

26 Methods Study protocol ( 4-month CMR study (chronic phase, Scout imaging Cine imaging LGE imaging ( mmol/kg Gadodiamide (0.2 JACC Cardiov. Imaging, 2010

27 Methods CMR measurements: LV volumes, mass and function AAR extent MI size Infarct transmurality ( MO ) Microvascular Obstruction ( MSI ) Myocardial salvage index T2-w STIR image LGE image Myocardial Salvage Index (MSI) = [ AAR extent MI size ] / AAR extent 15% Adverse LV remodeling = increase of LV ESV 12-lead ECG measurements: ST-segment elevation ECG 1 - ST-segment elevation ECG 2 X 100 Early ST-segment resolution = ST-segment elevation ECG 1 JACC Cardiov. Imaging, 2010

28 Results MSI: 0.49 A.S. male 72 years, acute infero-lateral ST-segment elevation MI, ( Pisa ) pre-pci time 4.3 hours MI size: 11% of LV MI transmurality: 61% AAR extent: 21% of LV How was effective the reperfusion therapy? M. van O. female 62 years, acute anterior ST-segment elevation MI, ( Leuven ) pre-pci time 5.3 hours MI size: 18% of LV MI tranmurality: 82% AAR extent: 35% of LV MSI: 0.48 JACC Cardiov. Imaging, 2010

29 Results Variables Acute phase Chronic phase P value (1-week) ( 4-month ) LV EDV (ml) 158 ± ± 41 < LV ESV (ml) 82 ± ± LV EF (%) 48 ± 8 50 ± LV mass (g) 124 ± ± 25 < AAR (% of LV) 32 ± MI size (% of LV) 18 ± ± 8 < MSI 0.46 ± Infarct transmurality (%) 72 ± MO (n, %) 69 (50) --- MO extent (% LV) 6 ± Early ST-segment res. (%) 57 ± 30 During follow-up 40 patients (29%) experienced adverse LV remodeling. JACC Cardiov. Imaging, 2010

30 Results Univariate and multivariate analyses for prediction of adverse LV remodeling Variables Unadjusted OR (95% CI) P value Adjusted OR (95% CI) P Value MI transmurality (%) 1.04 ( ) AAR (%) 1.04 ( ) ( ) MSI 0.58 ( ) < ( ) Presence of MO 6.79 ( ) < Time to reperfusion 1.00 ( ) Age 1.22 ( ) Anterior MI 2.27 ( ) LV EF 0.92 ( ) JACC Cardiov. Imaging, 2010

31 Results Univariate and multivariate anlyses for prediction of early ST-segment resolution Variables Univariate Analysis Multivariate Analysis B Coefficient P value B Coefficient P Value MI transmurality (%) < AAR (%) MSI 0.85 < < Presence of MO Time to reperfusion Age Anterior MI LV EF JACC Cardiov. Imaging, 2010

32 Limitations T2-weighted STIR imaging is particularly susceptible to signal loss in LV walls distant from the surface coil. Whether our findings apply also to patients with non reperfused MI or non ST-segment elevation MI needs to be established. Given the short follow-up, the influence of MSI on clinical outcomes was not assessed. Only 40 patients experienced adverse LV remodeling and this might have influenced the results of multivariate analysis. JACC Cardiov. Imaging, 2010

33 Conclusions and Clinical Implications CMR-derived myocardial salvage index (MSI) is a major and independent determinant of two important clinical and prognostic parameters: early ST-segment resolution and LV remodeling. MSI corrects the infarct size for the amount of AAR, yielding a marker with lower inherent variability, which can be particularly attractive in testing the efficacy and safety of new reperfusion approaches, before proving them In large randomized controlled trials. Considering that CMR-derived MSI is obtained after the acute phase (5±2 days) and without radiation exposure, its use offers considerable advantages compared to the well-validated 99m Tc-sestamibi myocardial scintigraphy. JACC Cardiov. Imaging, 2010

34 Conclusions The use of T2 w images is a powerfull tool to assess area at risk to detect AMI to assess RV involvement to assess myocardial salvage T2-weighted STIR imaging is particularly susceptible to signal loss in LV walls distant from the surface coil. Whether these findings apply also to patients with non reperfused MI or non ST-segment elevation MI needs to be established.

35 MR Cardiovascualr Unit at Fondazione C.N.R./Regione Toscana G. Monasterio.

36 From Stork A. et Al Eur Radiol 2006:16: l

37 Characterization of peri-infarction zone in T2 weighted MRI Stork A. et Al Eur Radiol 2006:16: l