Adam N Mather

Reperfusion haemorrhage as determined by cardiovascular MRI is a predictor of adverse left ventricular remodelling and markers of late arrhythmic risk

Background Interstitial haemorrhage due to reperfusion of severely ischaemic myocardium can be detected in vivo by T2-weighted (T2W) and T2* cardiovascular magnetic resonance (CMR). The clinical implications of myocardial haemorrhage following primary percutaneous coronary intervention (PPCI) remain undetermined. Objectives To assess whether the presence of myocardial haemorrhage influences ventricular remodelling and risk of late ventricular arrhythmia following PPCI for acute myocardial infarction (AMI). Methods Forty-eight patients with first ST-elevation AMI, treated successfully with PPCI, underwent CMR at day 2 and 3 months. Left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV) and left ventricular ejection fraction (LVEF) were determined from cine-CMR, infarct size and microvascular obstruction (MVO) from gadolinium-enhanced images and area at risk (AAR) from T2W CMR. Myocardial haemorrhage was defined as hypointense signal within the AAR on both T2W and T2* images. All patients had a signal-averaged electrocardiogram at 3 months. Results 30/48 (63%) patients had MVO and 12 of these showed myocardial haemorrhage. Patients with haemorrhagic myocardial infarction (MI) had significantly larger LVEDV and LVESV, lower LVEF and larger infarcts than those with non-haemorrhagic MI at baseline and at 3 months. The presence of haemorrhage was an independent predictor of adverse remodelling defined as increased LVESV on follow-up (p=0.001, OR 1.6) and prolonged filtered QRS (fQRS) on signal-averaged ECG at 3 months (p=0.020, OR 1.176). Conclusions Reperfusion haemorrhage following AMI is associated with larger infarct size, diminished myocardial salvage and lower LVEF. The presence of haemorrhage is the strongest independent predictor of adverse ventricular remodelling and is also associated with prolonged fQRS duration, which is a marker of arrhythmic risk.

Diffusion-weighted MRI determined cerebral embolic infarction following transcatheter aortic valve implantation: assessment of predictive risk factors and the relationship to subsequent health status

Background ‘Silent’ cerebral infarction and stroke are complications of transcatheter aortic valve implantation (TAVI). Objective To assess the occurrence of cerebral infarction, identify predictive risk factors and examine the impact on patient health-related quality of life (HRQoL). Methods Cerebral diffusion weighted MRI of 31 patients with aortic stenosis undergoing CoreValve TAVI was carried out. HRQoL was assessed at baseline and at 30 days by SF-12v2 and EQ5D questionnaires. Results New cerebral infarcts occurred in 24/31 patients (77%) and stroke in 2 (6%). Stroke was associated with a greater number and volume of cerebral infarcts. Age (r=0.37, p=0.042), severity of atheroma (arch and descending aorta; r=0.91, p<0.001, r=0.69, p=0.001, respectively) and catheterisation time (r=0.45, p=0.02) were predictors of the number of new cerebral infarcts. HRQoL improved overall: SF-12v2 physical component summary increased significantly (32.4±6.2 vs 36.5±7.2; p=0.03) with no significant change in mental component summary (43.5±11.7 vs 43.1±14.3; p=0.85). The EQ5D score and Visual Analogue Scale showed no significant change (0.56±0.26 vs 0.59±0.31; p=0.70, and 54.2±19 vs 58.2±24; p=0.43). Conclusion Multiple small cerebral infarcts occurred in 77% of patients with TAVI. The majority of infarcts were ‘silent’ with clinical stroke being associated with a both higher infarct number and volume. Increased age and the severity of aortic arch atheroma were independent risk factors for the development of new cerebral infarcts. Overall HRQoL improved and there was no association between the number of new cerebral infarcts and altered health status.

Appearance of microvascular obstruction on high resolution first-pass perfusion, early and late gadolinium enhancement CMR in patients with acute myocardial infarction

BackgroundThe presence and extent of microvascular obstruction (MO) after acute myocardial infarction can be measured by first-pass gadolinium-enhanced perfusion cardiovascular magnetic resonance (CMR) or after gadolinium injection with early or late enhancement (EGE/LGE) imaging. The volume of MO measured by these three methods may differ because contrast agent diffusion into the MO reduces its apparent extent over time. Theoretically, first-pass perfusion CMR should be the most accurate method to measure MO, but this technique has been limited by lower spatial resolution than EGE and LGE as well as incomplete cardiac coverage. These limitations of perfusion CMR can be overcome using spatio-temporal undersampling methods. The purpose of this study was to compare the extent of MO by high resolution first-pass k-t SENSE accelerated perfusion, EGE and LGE.Methods34 patients with acute ST elevation myocardial infarction, treated successfully with primary percutaneous coronary intervention (PPCI), underwent CMR within 72 hours of admission. k-t SENSE accelerated first-pass perfusion MR (7 fold acceleration, spatial resolution 1.5 mm × 1.5 mm × 10 mm, 8 slices acquired over 2 RR intervals, 0.1 mmol/kg Gd-DTPA), EGE (1-4 minutes after injection with a fixed TI of 440 ms) and LGE images (10-12 minutes after injection, TI determined by a Look-Locker scout) were acquired. MO volume was determined for each technique by manual planimetry and summation of discs methodology.Resultsk-t SENSE first-pass perfusion detected more cases of MO than EGE and LGE (22 vs. 20 vs. 14, respectively). The extent of MO imaged by first-pass perfusion (median mass 4.7 g, IQR 6.7) was greater than by EGE (median mass 2.3 g, IQR 7.1, p = 0.002) and LGE (median mass 0.2 g, IQR 2.4, p = 0.0003). The correlation coefficient between MO mass measured by first-pass perfusion and EGE was 0.91 (p < 0.001).ConclusionThe extent of MO following acute myocardial infarction appears larger on high-resolution first-pass perfusion CMR than on EGE and LGE. Given the inevitable time delay between gadolinium administration and acquisition of either EGE or LGE images, high resolution first-pass perfusion imaging may be the most accurate method to quantify MO.

Timing of Cardiovascular MR Imaging after Acute Myocardial Infarction: Effect on Estimates of Infarct Characteristics and Prediction of Late Ventricular Remodeling

PURPOSE To define the evolution of infarct characteristics with cardiovascular magnetic resonance (MR) imaging and to assess which of the cardiovascular MR data acquired at day 2 or at 1 week after acute myocardial infarction (AMI), is the stronger predictor of infarct size and left ventricular (LV) function measured at 3 months. MATERIALS AND METHODS The study protocol was reviewed and approved by the local research ethics committee, and written informed consent was obtained. Forty-eight patients with reperfused AMI underwent cine, T2-weighted, and late gadolinium enhancement cardiovascular MR imaging at days 2, 7, 30, and 90 after index presentation. Continuous data between times were compared by using paired t tests or one-way analysis of variance. Multiple linear regression analyses were used to predict linear end points. RESULTS Infarct size and extent of myocardial edema decreased significantly between day 2 and 1 week: Mean scar as a percentage of LV mass and standard deviation (SD), respectively, were 27.2 and 13.9 versus 21.6 and 14.1 (P < .001), and myocardial edema as a percentage of LV mass and SD, respectively, were 37.9 and 15.2 versus 32.3 and 14.3 (P = .003). These changes were accompanied by a significant improvement in LV ejection fraction (LVEF): Mean percentage of LVEF and SD, respectively, were 41.7 and 9.6 versus 44.6 and 10.1 (P < .001). When comparing data acquired at day 2 and 1 week, only cardiovascular MR data acquired at 1 week were independent predictors of LVEF and infarct size at 3 months. CONCLUSION LVEF, infarct size, and extent of myocardial edema changed significantly during the 1st week after AMI. Overall, cardiovascular MR measurements acquired after 1 week have greater predictive value for infarct size and LV function at 3 months than data acquired at day 2.

Assessment of valve haemodynamics, reverse ventricular remodelling and myocardial fibrosis following transcatheter aortic valve implantation compared to surgical aortic valve replacement: a cardiovascular magnetic resonance study

Objective To compare the effects of transcatheter aortic valve implantation (TAVI) and surgical aortic valve replacement (SAVR) on aortic valve haemodynamics, ventricular reverse remodelling and myocardial fibrosis (MF) by cardiovascular magnetic resonance (CMR) imaging. Design A 1.5 T CMR scan was performed preoperatively and 6 months postoperatively. Setting University hospitals of Leeds and Leicester, UK. Patients 50 (25 TAVI, 25 SAVR; age 77±8 years) high-risk severe symptomatic aortic stenosis (AS) patients. Main outcome measures Valve haemodynamics, ventricular volumes, ejection fraction (EF), mass and MF. Results Patients were matched for gender and AS severity but not for age (80±6 vs 73±7 years, p=0.001) or EuroSCORE (22±14 vs 7±3, p<0.001). Aortic valve mean pressure gradient decreased to a greater degree post-TAVI compared to SAVR (21±8 mm Hg vs 35±13 mm Hg, p=0.017). Aortic regurgitation reduced by 8% in both groups, only reaching statistical significance for TAVI (p=0.003). TAVI and SAVR improved (p<0.05) left ventricular (LV) end-systolic volumes (46±18 ml/m2 vs 41±17 ml/m2; 44±22 ml/m2 vs32±6 ml/m2) and mass (83±20 g/m2 vs 65±15 g/m2; 74±11 g/m2 vs 59±8 g/m2). SAVR reduced end-diastolic volumes (92±19 ml/m2 vs 74±12 ml/m2, p<0.001) and TAVI increased EF (52±12% vs 56±10%, p=0.01). MF reduced post-TAVI (10.9±6% vs 8.5±5%, p=0.03) but not post-SAVR (4.2±2% vs 4.1±2%, p=0.98). Myocardial scar (p≤0.01) and baseline ventricular volumes (p<0.001) were the major predictors of reverse remodelling. Conclusions TAVI was comparable to SAVR at LV reverse remodelling and superior at reducing the valvular pressure gradient and MF. Future work should assess the prognostic importance of reverse remodelling and fibrosis post-TAVI to aid patient selection.

Serial Change in Health-Related Quality of Life Over 1 Year After Transcatheter Aortic Valve Implantation: Predictors of Health Outcomes

OBJECTIVES The goal of this study was to assess serial changes in patient health-related quality of life (HRQOL) over time and identify predictors of patient benefit. BACKGROUND Severe aortic stenosis reduces the length and quality of a patients life. Transcatheter aortic valve implantation (TAVI) is superior to standard medical therapy and noninferior to surgical aortic valve replacement for 1-year mortality. HRQOL is an important outcome measure for which there is limited evidence in TAVI populations. METHODS A total of 102 patients (mean age 80 ± 0.6 years; 49% male) undergoing TAVI consented to participate. Two HRQOL questionnaires-the social functioning (SF)-12v2 with physical component summaries (PCS) and mental component summaries (MCS) and the EQ-5D (with a visual analog scale [VAS])-were completed at baseline, 30 days, 6 months, and 1 year according to the recommendations of the Valve Academic Research Consortium. A SF-6D utility measure was calculated from the SF-12 survey. RESULTS HRQOL significantly improved over 1 year (PCS p = 0.02; EQ-5D p = 0.02; VAS p = 0.01; SF-6D p = 0.03), becoming similar to age-adjusted U.S. population norms. The greatest change occurred from baseline to 30 days (p < 0.001), with further significant improvements to 6 months (p < 0.01). An insignificant decline occurred between 6 months and 1 year (p > 0.05), but a linear pattern of change remained for PCS, EQ-5D, and VAS (p < 0.05). Male sex (SF-6D p = 0.01) and increased operator experience (PCS, EQ-5D, and VAS p < 0.05) were independent predictors of a greater improvement in HRQOL. CONCLUSIONS HRQOL significantly improved early after TAVI and was maintained out to 1 year. Patient factors, procedural complications, and operator experience are predictors of health benefit at 1 year.

Collateral Donor Artery Physiology and the Influence of a Chronic Total Occlusion on Fractional Flow Reserve

Background—The presence of a concomitant chronic total coronary occlusion (CTO) and a large collateral contribution might alter the fractional flow reserve (FFR) of an interrogated vessel, rendering the FFR unreliable at predicting ischemia should the CTO vessel be revascularized and potentially affecting the decision on optimal revascularization strategy. We tested the hypothesis that donor vessel FFR would significantly change after percutaneous coronary intervention of a concomitant CTO. Methods and Results—In consecutive patients undergoing percutaneous coronary intervention of a CTO, coronary pressure and flow velocity were measured at baseline and hyperemia in proximal and distal segments of both nontarget vessels, before and after percutaneous coronary intervention. Hemodynamics including FFR, absolute coronary flow, and the coronary flow velocity–pressure gradient relation were calculated. After successful percutaneous coronary intervention in 34 of 46 patients, FFR in the predominant donor vessel increased from 0.782 to 0.810 (difference, 0.028 [0.012 to 0.044]; P=0.001). Mean decrease in baseline donor vessel absolute flow adjusted for rate pressure product: 177.5 to 139.9 mL/min (difference −37.6 [−62.6 to −12.6]; P=0.005), mean decrease in hyperemic flow: 306.5 to 272.9 mL/min (difference, −33.5 [−58.7 to −8.3]; P=0.011). Change in predominant donor vessel FFR correlated with angiographic (%) diameter stenosis severity (r=0.44; P=0.009) and was strongly related to stenosis severity measured by the coronary flow velocity–pressure gradient relation (r=0.69; P<0.001). Conclusions—Recanalization of a CTO results in a modest increase in the FFR of the predominant collateral donor vessel associated with a reduction in coronary flow. A larger increase in FFR is associated with greater coronary stenosis severity.

Relationship of dysglycemia to acute myocardial infarct size and cardiovascular outcome as determined by cardiovascular magnetic resonance

BackgroundImproved outcomes for normoglycemic patients suffering acute myocardial infarction (AMI) over the last decade have not been matched by similar improvements in mortality for diabetic patients despite similar levels of baseline risk and appropriate medical therapy. Two of the major determinants of poor outcome following AMI are infarct size and left ventricular (LV) dysfunction.MethodsNinety-three patients with first AMI were studied. 22 patients had diabetes mellitus (DM) based on prior history or admission blood glucose ≥11.1 mmol/l. 13 patients had dysglycemia (admission blood glucose ≥7.8 mmol/l but <11.1 mmol/l) and 58 patients had normoglycemia (admission blood glucose <7.8 mmol/l). Patients underwent cardiac magnetic resonance (CMR) imaging at index presentation and median follow-up of 11 months. Cine imaging assessed LV function and late gadolinium contrast-enhanced imaging was used to quantify infarct size. Clinical outcome data were collected at 18 months median follow-up.ResultsPatients with dysglycemia and DM had larger infarct sizes by CMR than normoglycemic patients; at baseline percentage LV scar (mean (SD)) was 23.0% (10.9), 25.6% (12.9) and 15.8% (10.3) respectively (p = 0.001), and at 11 months percentage LV scar was 17.6% (8.9), 19.1% (9.6) and 12.4% (7.8) (p = 0.017). Patients with dysglycemia and DM also had lower event-free survival at 18 months (p = 0.005).ConclusionsPatients with dysglycemia or diabetes mellitus sustain larger infarct sizes than normoglycemic patients, as determined by CMR. This may, in part, account for their adverse prognosis following AMI.

Relationship between Myocardial Edema and Regional Myocardial Function after Reperfused Acute Myocardial Infarction: An MR Imaging Study

PURPOSE To compare the relationship of myocardial edema and corresponding contractile function over time in patients with reperfused acute myocardial infarction (AMI). MATERIALS AND METHODS This study was approved by the regional ethics committee; all patients gave written informed consent. Thirty-nine patients (34 men; mean age, 57 years; age range, 35-73 years) underwent T2-weighted, tagging, and late gadolinium enhancement magnetic resonance imaging at three time points after primary percutaneous coronary intervention for ST-elevation AMI. Circumferential strain, T2-weighted signal intensity, and volume of infarct zones, peri-infarct zones, and remote myocardium were measured. Patients were stratified by presence or absence of peri-infarct edema, defined as areas with T2-weighted signal intensity of two or more standard deviations above that of remote myocardium. Statistical analysis was performed with repeated-measures analysis of variance with post hoc Bonferroni correction. RESULTS Edematous peri-infarct myocardium had attenuated strain compared with remote myocardium at day 2 (-0.137 vs -0.226, P < .001), day 30 (-0.188 vs -0.240, P < .01), and day 90 (-0.207 vs -0.241, P = .01). Nonedematous peri-infarct myocardium had similar (P > .05) strain to remote myocardium at all time points. Strain improved in edematous peri-infarct myocardium at day 30 (P = .02) and day 90 (P < .01), closely mirroring resolution of intensity and volume of edema. Decreased strain correlated with edema volume (r = 0.30, P = .01) and normalized edema signal intensity (r = 0.28, P < .01). In eight patients with fully transmural infarction, infarct zone strain improved between day 2 and day 90 (P = .02). CONCLUSION Improvement of strain in peri-infarct myocardium closely follows regression of myocardial edema. Volume of edema and intensity of signal on T2-weighted images relate to functional recovery after reperfused AMI.

Systolic versus Diastolic Acquisition in Myocardial Perfusion MR Imaging

PURPOSE To compare myocardial blood flow (MBF) at systole and diastole and determine the diagnostic accuracy of both phases in patients suspected of having coronary artery disease (CAD). MATERIALS AND METHODS The study was approved by the regional ethics committee, and all patients gave written informed consent. After coronary angiography, 40 patients (27 men; mean age, 64 years ± 8) underwent stress-rest perfusion magnetic resonance (MR) imaging at 1.5 T, with images aquired simultaneously at end systole and middiastole. Patients were classified as having CAD (stenosis .70%) or no significant CAD. In patients with CAD, myocardial segments were classified as stenosis-dependent (downstream of significant stenosis) or remote. MBF and myocardial perfusion reserve (MPR) were calculated for each segment, and mean values in each phase were compared with paired t tests. The diagnostic accuracy of each phase was determined with receiver operating characteristic (ROC) analysis. RESULTS Twenty-one of the 40 patients (53%) had CAD. Resting MBF was similar in both phases for patients with and patients without CAD (P > .05). Stress MBF was greater in diastole than systole in normal, remote, and stenosis-dependent segments (3.75 mL/g/min ± 1.50 vs 3.15 mL/g/min ± 1.10, respectively, for normal segments; 2.75 mL/g/min ± 1.20 vs 2.38 mL/g/min ± 0.99, respectively, for remote segments; 2.49 mL/g/min ± 1.07 vs 2.23 mL/g/min ± 0.90, respectively, for stenosis-dependent segments; P <.01). MPR was greater in diastole than systole in all segment groups (P < .05). The diagnostic accuracies at diastole and systole were similar (area under the ROC curve = 0.79 and 0.82, respectively; P = .30). CONCLUSION Myocardial perfusion MR estimates of stress MBF and MPR were greater in diastole than systole in patients with and patients without CAD. However, both phases had similar diagnostic accuracy. These observations may be relevant to other dynamic perfusion methods, including computed tomography and echocardiography.