Alexander R. Payne

Bright-Blood T2-Weighted MRI Has Higher Diagnostic Accuracy Than Dark-Blood Short Tau Inversion Recovery MRI for Detection of Acute Myocardial Infarction and for Assessment of the Ischemic Area at Risk and Myocardial Salvage

Background— T2-Weighted MRI reveals myocardial edema and enables estimation of the ischemic area at risk and myocardial salvage in patients with acute myocardial infarction (MI). We compared the diagnostic accuracy of a new bright-blood T2-weighted with a standard black blood T2-weighted MRI in patients with acute MI. Methods and Results— A breath-hold, bright-blood T2-weighted, Acquisition for Cardiac Unified T2 Edema pulse sequence with normalization for coil sensitivity and a breath-hold T2 dark-blood short tau inversion recovery sequence were used to depict the area at risk in 54 consecutive acute MI patients. Infarct size was measured on gadolinium late contrast enhancement images. Compared with dark-blood T2-weighted MRI, consensus agreements between independent observers for identification of myocardial edema were higher with bright-blood T2-weighted MRI when evaluated per patient (P<0.001) and per segment of left ventricle (P<0.001). Compared with bright-blood T2-weighted MRI, dark-blood T2-weighted MRI underestimated the area at risk compared with infarct size (P<0.001). The 95% limits of agreement for interobserver agreements for the ischemic area at risk and myocardial salvage were wider with dark-blood T2-weighted MRI than with bright-blood T2-weighted MRI. Bright blood enabled more accurate identification of the culprit coronary artery with correct identification in 94% of cases compared with 61% for dark blood (P<0.001). Conclusions— Bright-blood T2-weighted MRI has higher diagnostic accuracy than dark-blood T2-weighted MRI. Additionally, dark-blood T2-weighted MRI may underestimate area at risk and myocardial salvage.

Bright Blood T2 Weighted MRI Has Higher Diagnostic Accuracy Than Dark Blood STIR MRI for Detection of Acute Myocardial Infarction and for Assessment of the Ischemic Area-at-Risk and Myocardial Salvage

Background— T2-Weighted MRI reveals myocardial edema and enables estimation of the ischemic area at risk and myocardial salvage in patients with acute myocardial infarction (MI). We compared the diagnostic accuracy of a new bright-blood T2-weighted with a standard black blood T2-weighted MRI in patients with acute MI. Methods and Results— A breath-hold, bright-blood T2-weighted, Acquisition for Cardiac Unified T2 Edema pulse sequence with normalization for coil sensitivity and a breath-hold T2 dark-blood short tau inversion recovery sequence were used to depict the area at risk in 54 consecutive acute MI patients. Infarct size was measured on gadolinium late contrast enhancement images. Compared with dark-blood T2-weighted MRI, consensus agreements between independent observers for identification of myocardial edema were higher with bright-blood T2-weighted MRI when evaluated per patient (P<0.001) and per segment of left ventricle (P<0.001). Compared with bright-blood T2-weighted MRI, dark-blood T2-weighted MRI underestimated the area at risk compared with infarct size (P<0.001). The 95% limits of agreement for interobserver agreements for the ischemic area at risk and myocardial salvage were wider with dark-blood T2-weighted MRI than with bright-blood T2-weighted MRI. Bright blood enabled more accurate identification of the culprit coronary artery with correct identification in 94% of cases compared with 61% for dark blood (P<0.001). Conclusions— Bright-blood T2-weighted MRI has higher diagnostic accuracy than dark-blood T2-weighted MRI. Additionally, dark-blood T2-weighted MRI may underestimate area at risk and myocardial salvage.

Microvascular Resistance Predicts Myocardial Salvage and Infarct Characteristics in ST-Elevation Myocardial Infarction

Background The pathophysiology of myocardial injury and repair in patients with ST‐elevation myocardial infarction is incompletely understood. We investigated the relationships among culprit artery microvascular resistance, myocardial salvage, and ventricular function. Methods and Results The index of microvascular resistance (IMR) was measured by means of a pressure‐ and temperature‐sensitive coronary guidewire in 108 patients with ST‐elevation myocardial infarction (83% male) at the end of primary percutaneous coronary intervention. Paired cardiac MRI (cardiac magnetic resonance) scans were performed early (2 days; n=108) and late (3 months; n=96) after myocardial infarction. T2‐weighted‐ and late gadolinium–enhanced cardiac magnetic resonance delineated the ischemic area at risk and infarct size, respectively. Myocardial salvage was calculated by subtracting infarct size from area at risk. Univariable and multivariable models were constructed to determine the impact of IMR on cardiac magnetic resonance–derived surrogate outcomes. The median (interquartile range) IMR was 28 (17–42) mm Hg/s. The median (interquartile range) area at risk was 32% (24%–41%) of left ventricular mass, and the myocardial salvage index was 21% (11%–43%). IMR was a significant multivariable predictor of early myocardial salvage, with a multiplicative effect of 0.87 (95% confidence interval 0.82 to 0.92) per 20% increase in IMR; P<0.001. In patients with anterior myocardial infarction, IMR was a multivariable predictor of early and late myocardial salvage, with multiplicative effects of 0.82 (95% confidence interval 0.75 to 0.90; P<0.001) and 0.92 (95% confidence interval 0.88 to 0.96; P<0.001), respectively. IMR also predicted the presence and extent of microvascular obstruction and myocardial hemorrhage. Conclusion Microvascular resistance measured during primary percutaneous coronary intervention significantly predicts myocardial salvage, infarct characteristics, and left ventricular ejection fraction in patients with ST‐elevation myocardial infarction. (J Am Heart Assoc. 2012;1:e002246 doi: 10.1161/JAHA.112.002246)

Bright-blood T(2)-weighted MRI has high diagnostic accuracy for myocardial hemorrhage in myocardial infarction: a preclinical validation study in swine.

Background— Myocardial hemorrhage after myocardial infarction (MI) usually goes undetected. We investigated the diagnostic accuracy of bright-blood T2-weighted cardiac MRI for myocardial hemorrhage in experimental MI. Methods and Results— MI was created in swine by occluding the left anterior descending (n=10) or circumflex (n=5) coronary arteries for 90 minutes followed by reperfusion for ⩽3 days (n=2), 10 days (n=7), or 60 days (n=6). MRI was performed at 1.5 T, using bright-blood T2-prepared steady-state free-precession, T2* and early (1 minute) and late (10–15 minutes) gadolinium enhancement (EGE, LGE, respectively) MRI. Left ventricular sections and histology were assessed for hemorrhage by an experienced cardiac pathologist blinded to the MRI data. Hypointense regions on T2-weighted and contrast-enhanced MRI were independently determined by 3 cardiologists experienced in MRI who were also blinded to the pathology results. Eighty ventricular pathological sections were matched with MRI (n=68 for EGE MRI). All sections with evidence of MI (n=63, 79%) also exhibited hyperintense zones consistent with edema on T2-weighted MRI and infarct on LGE MRI. Myocardial hemorrhage occurred in 49 left ventricular sections (61%) and corresponded with signal voids on 48 T2-weighted (98%) and 26 LGE-MRI (53%). Alternatively, signal voids occurred in the absence of hemorrhage in 3 T2-weighted (90% specificity) and 5 LGE MRI (84% specificity). On EGE MRI, 27 of 43 cases of early microvascular obstruction corresponded with hemorrhage (63% sensitivity), whereas 5 of 25 defects occurred in the absence of hemorrhage (80% specificity). The positive and negative predictive values for pathological evidence of hemorrhage were 94% and 96% for T2-weighted, 84% and 55% for LGE MRI, and 85% and 56% for EGE MRI. Conclusions— Bright-blood T2-weighted MRI has high diagnostic accuracy for myocardial hemorrhage.

Vasodilatory Capacity of the Coronary Microcirculation is Preserved in Selected Patients With Non–ST-Segment–Elevation Myocardial Infarction

Background—The use of fractional flow reserve in patients with non–ST-segment–elevation myocardial infarction (NSTEMI) is a controversial issue. We undertook a study to assess the vasodilatory capacity of the coronary microcirculation in patients with NSTEMI when compared with a model of preserved microcirculation (stable angina [SA] cohort: culprit and nonculprit vessel) and acute microcirculatory dysfunction (ST-segment–elevation myocardial infarction [STEMI] cohort). We hypothesized that the vasodilatory response of the microcirculation would be preserved in NSTEMI. Methods and Results—A total of 140 patients undergoing single vessel percutaneous coronary intervention were included: 50 stable angina, 50 NSTEMI, and 40 STEMI. The index of microvascular resistance (IMR), fractional flow reserve, and coronary flow reserve were measured before stenting in the culprit vessel and in an angiographically normal nonculprit vessel in patients with SA. The resistive reserve ratio, a measure of the vasodilatory capacity of the microcirculation and calculated using the equation: baseline resistance index (TmnBase×PaBase[PdBase–Pw/PaBase–Pw])–IMR/IMR, where TmnBase referred to nonhyperemic transit time; PaBase and PdBase, the nonhyperemic aortic and distal coronary pressures, respectively; and Pw referred to the coronary wedge pressure, was also measured. Troponin was also measured ⩽24 hours after percutaneous coronary intervention. The resistive reserve ratio was significantly lower in the STEMI patients compared with the stable angina patients both culprit and nonculprit vessel (STEMI, 1.7 versus SA culprit, 2.8; P⩽0.001 and SA nonculprit, 2.9; P<0.0001) and compared with NSTEMI patients (NSTEMI, 2.46; P⩽0.001). The resistive reserve ratio was similar in stable angina and NSTEMI patients (P=0.6). IMR was significantly higher pre-PCI in STEMI compared with SA and NSTEMI (IMR STEMI, 36.51 versus IMR NSTEMI, 22.73 [P=0.01] versus IMR SA, 18.26 [P<0.0001]). However, there was no significant difference in IMR pre-PCI between NSTEMI and SA (IMR NSTEMI, 22.73; IMR SA, 18.26 [P=0.1]). Conclusions—The vasodilatory capacity of the microcirculation is preserved in selected patients with NSTEMI. The clinical use of fractional flow reserve in the culprit vessel may be preserved in selected patents with NSTEMI.

Infarct size and left ventricular remodelling after preventive percutaneous coronary intervention

Objective We hypothesised that, compared with culprit-only primary percutaneous coronary intervention (PCI), additional preventive PCI in selected patients with ST-elevation myocardial infarction with multivessel disease would not be associated with iatrogenic myocardial infarction, and would be associated with reductions in left ventricular (LV) volumes in the longer term. Methods In the preventive angioplasty in myocardial infarction trial (PRAMI; ISRCTN73028481), cardiac magnetic resonance (CMR) was prespecified in two centres and performed (median, IQR) 3 (1, 5) and 209 (189, 957) days after primary PCI. Results From 219 enrolled patients in two sites, 84% underwent CMR. 42 (50%) were randomised to culprit-artery-only PCI and 42 (50%) were randomised to preventive PCI. Follow-up CMR scans were available in 72 (86%) patients. There were two (4.8%) cases of procedure-related myocardial infarction in the preventive PCI group. The culprit-artery-only group had a higher proportion of anterior myocardial infarctions (MIs) (55% vs 24%). Infarct sizes (% LV mass) at baseline and follow-up were similar. At follow-up, there was no difference in LV ejection fraction (%, median (IQR), (culprit-artery-only PCI vs preventive PCI) 51.7 (42.9, 60.2) vs 54.4 (49.3, 62.8), p=0.23), LV end-diastolic volume (mL/m2, 69.3 (59.4, 79.9) vs 66.1 (54.7, 73.7), p=0.48) and LV end-systolic volume (mL/m2, 31.8 (24.4, 43.0) vs 30.7 (23.0, 36.3), p=0.20). Non-culprit angiographic lesions had low-risk Syntax scores and 47% had non-complex characteristics. Conclusions Compared with culprit-only PCI, non-infarct-artery MI in the preventive PCI strategy was uncommon and LV volumes and ejection fraction were similar.

LEFT VENTRICULAR OUTCOMES FOLLOWING MULTIVESSEL PCI VERSUS INFARCT-ONLY PCI IN PATIENTS WITH ACUTE STEMI: THE GLASGOW PRAMI CMR SUB-STUDY

In the Randomized Trial of Preventive Angioplasty in Myocardial Infarction (PRAMI; [ISRCTN73028481][1]), compared with infarct-related artery (IRA)-only PCI, additional immediate multivessel PCI (MV-PCI) of non-IRA improved long term prognosis. We studied left ventricular (LV) outcomes in a pre-

Infarct burden following multivessel PCI vs. infarct-only PCI in patients with acute STEMI: the Glasgow PRAMI CMR sub-study

Background: In the Preventive Angioplasty in Myocardial Infarction trial (PRAMI; ISRCTN73028481), immediate multivessel PCI (MV-PCI) of non-IRA (infarct related artery) lesions in patients with acute ST elevation myocardial infarction (STEMI) and multivessel coronary disease (MVD) improved long term prognosis. We assessed infarct distribution and size in a pre-specified cardiac magnetic resonance (CMR) sub-study. Methods: In this single centre prospective sub-study, PRAMI participants were invited to undergo 1.5 Tesla CMR 1 week and 1 year after primary PCI. The CMR scans were analysed using semi-automated software by a clinician blinded to treatment group assignment and clinical outcomes. The presence and extent of infarction were assessed quantitatively with late gadolinium enhancement (LGE) imaging (Gadovist, 0.1 mmol/kg). The infarct was delineated as an area of myocardial enhancement (cm2) using a signal intensity threshold of >5SDs above a remote region, and expressed as a % of total LV mass. The incidence of new LGE in non-infarct related artery territories at baseline and 1 year were assessed. Data were analysed by an independent statistician. Results: Of 465 randomised trial participants in 6 UK hospitals, 138 (30%) were enrolled in Glasgow. Of these 80 patients underwent CMR 1 week post primary PCI of whom 41 (51%) were in the multi-vessel PCI group and 39 (49%) were in the IRA-only group. At 1 year, 69 (86%) patients had a follow up CMR scan. Infarct size and distribution are described in Table 1.

Left ventricular outcomes following multivessel PCI vs. infarct artery-only PCI in patients with acute STEMI: the Glasgow PRAMI CMR sub-study

Background In the Randomized Trial of Preventive Angioplasty in Myocardial Infarction (PRAMI; ISRCTN73028481), compared with infarct-related artery (IRA)-only PCI, additional immediate multivessel PCI (MV-PCI) of nonIRA lesions in patients with acute ST elevation myocardial infarction (STEMI) and multivessel coronary disease (MVD) improved long term prognosis. We studied left ventricular (LV) outcomes in a pre-specified cardiac magnetic resonance (CMR) sub-study.

Diagnostic utility of cardiac magnetic resonance imaging in STEMI survivors after emergency PCI

emergency PCI R.J. McGeoch ⁎, A.R. Payne , R. Woodward , A. Saul , T. Steedman , J. Foster , S. Hood , E. Peat , M.M. Lindsay , M.C. Petrie , A.P. Rae , M. McEntegart , H. Eteiba , N. Tzemos , K.G. Oldroyd , C. Berry a,b,c a Glasgow Heart and Lung Institute, Golden Jubilee National Hospital, Clydebank, United Kingdom b Department of Cardiology Western Infirmary, Glasgow, United Kingdom c BHF Glasgow Cardiovascular Research Centre, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom