Mohammad I. Zia

Characterizing Myocardial Edema and Hemorrhage Using Quantitative T2 and T2* Mapping at Multiple Time Intervals Post ST-Segment Elevation Myocardial Infarction

Background—Accurate characterization of the longitudinal trends of myocardial edema and hemorrhage has been previously limited by subjective qualitative methods. We aimed to prospectively characterize the evolution of myocardial edema and hemorrhage post acute myocardial infarction using quantitative measures. Methods and Results—Sixty-two patients were enrolled post primary percutaneous coronary intervention and underwent cardiovascular magnetic resonance on a 1.5-T scanner at 48 hours, 3 weeks, and 6 months. Myocardial edema and hemorrhage were assessed by T2 and T2* mapping, respectively, in both infarct segment (IS) and remote segment (RS). At 48 hours, T2 is higher in IS compared with RS (56.7 ms versus 43.4 ms; P<0.01). At 3 weeks T2 remains higher in IS compared with RS (51.8 ms versus 39.5 ms; P<0.01), and subsequently equalizes by 6 months (39.8 ms versus 39.5 ms; P=nonsignificant). T2 is also increased in RS at day 2 versus 3 weeks (43.4 ms versus 39.5 ms; P<0.01). At 48 hours T2* was reduced in IS compared with RS (32.4 ms versus 37.4 ms; P<0.01). At 3 weeks (IS, 37.7 ms versus RS, 38.4 ms; P=nonsignificant) and 6 months (IS, 37.3 ms versus RS, 38.2 ms; P=nonsignificant), T2* values were equal in both segments. Conclusions—Quantification of myocardial edema and hemorrhage by T2 and T2* mapping is feasible post acute myocardial infarction and demonstrates that hemorrhage resolves faster than edema. Noninfarcted segments can also demonstrate edema in the acute phase possibly due to global hyperemia.

Paradoxical use of invasive cardiac procedures for patients with non-ST segment elevation myocardial infarction: An international perspective from the CRUSADE Initiative and the Canadian ACS Registries I and II

BACKGROUND Practice guidelines support an early invasive strategy in patients with non-ST segment elevation acute coronary syndromes, particularly in those at higher risk. OBJECTIVES To compare North American rates of invasive cardiac procedure use stratified by risk. METHODS Use of invasive cardiac procedures and other care patterns in patients with non-ST segment elevation acute coronary syndromes from the United States (US) Can Rapid risk stratification of Unstable angina patients Suppress ADverse outcomes with Early implementation of the ACC/AHA guidelines (CRUSADE) National Quality Improvement Initiative (n=88,097; 465 hospitals) and Canadian ACS Registries I (n=1270; 51 hospitals) and II (n=1473; 36 hospitals) were compared after dividing patients into different risk categories based on predicted risk of in-hospital mortality. RESULTS While the overall use of invasive procedures was higher in the US, high-risk patients were least likely to undergo coronary angiography (41% versus 64% in Canada [P<0.0001] and 53% versus 76% in the United States [P<0.0001]) and percutaneous coronary intervention (14% versus 32% in Canada [P<0.0001] and 28% versus 51% in the US [P<0.0001]) compared with low-risk patients in both countries, and had longer median waiting times for these procedures (120 h versus 96 h in Canada [P<0.0001] and 34 h versus 23 h in the US [P<0.0001] for coronary angiography). CONCLUSIONS The inverse relationship between risk level and the use of invasive cardiac procedures for patients in the US and Canada suggests that a risk stratification-guided approach for triaging patients to an early invasive management strategy is paradoxically used. This incongruous relationship holds true regardless of resource availability or overall rates of cardiac catheterization.

Thrombus aspiration during primary percutaneous coronary intervention is associated with reduced myocardial edema, hemorrhage, microvascular obstruction and left ventricular remodeling

BackgroundThrombus aspiration (TA) has been shown to improve microvascular perfusion during primary percutaneous coronary intervention (PCI) for patients with ST-segment elevation myocardial infarction (STEMI). The objective of our study was to assess the relationship between TA and myocardial edema, myocardial hemorrhage, microvascular obstruction (MVO) and left ventricular remodeling in STEMI patients using cardiovascular magnetic resonance (CMR).MethodsSixty patients were enrolled post primary PCI and underwent CMR on a 1.5 T scanner at 48 hours and 6 months. Patients were retrospectively stratified into 2 groups: those that received TA (35 patients) versus that did not receive thrombus aspiration (NTA) (25 patients). Myocardial edema and myocardial hemorrhage were assessed by T2 and T2* quantification respectively. MVO was assessed via a contrast-enhanced T1-weighted inversion recovery gradient-echo sequence.ResultsAt 48 hours, infarct segment T2 (NTA 57.9 ms vs. TA 52.1 ms, p = 0.022) was lower in the TA group. Also, infarct segment T2* was higher in the TA group (NTA 29.3 ms vs. TA 37.8 ms, p = 0.007). MVO incidence was lower in the TA group (NTA 88% vs. TA 54%, p = 0.013).At 6 months, left ventricular end-diastolic volume index (NTA 91.9 ml/m2 vs. TA 68.3 ml/m2, p = 0.013) and left ventricular end systolic volume index (NTA 52.1 ml/m2 vs. TA 32.4 ml/m2, p = 0.008) were lower and infarct segment systolic wall thickening was higher in the TA group (NTA 3.5% vs. TA 74.8%, p = 0.003).ConclusionTA during primary PCI is associated with reduced myocardial edema, myocardial hemorrhage, left ventricular remodeling and incidence of MVO after STEMI.

Correlation of late gadolinium enhancement MRI and quantitative T2 measurement in cardiac sarcoidosis

To investigate the potentially improved detection and quantification of cardiac involvement using novel late‐gadolinium‐enhancement (LGE) cardiac magnetic resonance imaging (MRI) and quantitative T2 measurement to achieve better myocardial tissue characterization in systemic sarcoidosis.

Percutaneous Coronary Intervention With vs Without On-Site Cardiac Surgery Backup: A Systematic Review and Meta-analysis

Although the popularity of performing percutaneous coronary intervention (PCI) in centres without on-site cardiac surgery backup is increasing, the safety of this practice is unknown. Our goal was to perform a systematic review and meta-analysis of PCI with and without on-site cardiac surgery backup. We identified studies using computerized literature searches through July 2009. Main outcomes of interest included in-hospital mortality and early coronary artery bypass grafting (CABG). Analyses were stratified by procedure indication (primary PCI and nonprimary PCI). Pooled estimates were obtained using random-effects models. We identified 9 primary PCI studies (106,089 patients) and 7 nonprimary studies (910,422 patients) comparing centres with and without on-site cardiac surgery. For primary PCI, centres without on-site surgery had no significantly increased risk of in-hospital mortality (odds ratio [OR] 0.93; 95% confidence interval [CI], 0.83-1.05) or early CABG (OR 0.87; 95% CI, 0.68-1.11) compared with centres with on-site surgery. For nonprimary PCI, no increased risk of in-hospital mortality (OR 1.03; 95% CI, 0.64-1.66) and early CABG (OR 1.38; 95% CI, 0.65-2.95) was observed in centres without backup. However, significant heterogeneity existed in estimates of nonprimary PCI studies, suggesting substantial variation in outcomes of nonprimary PCI across centres without on-site cardiac surgery. We demonstrated that rates of in-hospital mortality and early CABG were similar at PCI centres with and without on-site cardiac surgery backup. However, variations in outcomes suggest that assurance of optimal outcomes at each PCI centre without on-site surgery is needed.

Long-Term Safety and Effectiveness of Drug-Eluting Stents for the Treatment of Saphenous Vein Grafts Disease: A Population-Based Study

OBJECTIVES The purpose of this study was to evaluate the long-term safety and effectiveness of drug-eluting stents (DES) for the treatment of saphenous vein graft (SVG) disease. BACKGROUND DES are frequently implanted for SVG interventions, but some studies have shown that they are not effective in reducing target vessel revascularization (TVR) over longer-term follow-up. Some studies suggest there is increased mortality with DES compared with bare-metal stents (BMS). METHODS We performed propensity score matching analysis using a population-based cohort that included 709 well-matched pairs (n = 1,418) who received DES or BMS for the treatment of SVG disease from 2003 to 2008. Outcomes of interest included repeat TVR, myocardial infarction, and death. RESULTS The mean age of the propensity-matched cohort was 69 years, 50% had diabetes, and the mean age of SVG was 10.6 years. At 4-year follow-up, the rate of repeat TVR was 21% in the DES group and 27.6% in the BMS group (p = 0.004). DES implantation was associated with the largest TVR reduction among patients with diabetes and patients receiving longer stents (≥30 mm) and the number of procedures needed to prevent a TVR at 4 years was 8 and 7, respectively. The composite rate of myocardial infarction or death was not significantly different between DES and BMS at 4 years (27.8% vs. 32.6%, p = 0.09). CONCLUSIONS Implantation of DES in the treatment of SVG disease is associated with substantial reduction of repeat revascularization, without evidence of an increased risk of myocardial infarction or death at longer-term follow-up.

Comparison of the frequencies of myocardial edema determined by cardiac magnetic resonance in diabetic versus nondiabetic patients having percutaneous coronary intervention for ST elevation myocardial infarction.

The specific mechanisms by which diabetes may affect the myocardial tissue response to ischemia are unclear. Our objective was to prospectively quantify the degree of myocardial edema in diabetics versus nondiabetics with ST elevation myocardial infarction using cardiac magnetic resonance. Fifty-two patients (16 diabetics and 36 nondiabetics) were enrolled after primary percutaneous coronary intervention and underwent cardiac magnetic resonance on a 1.5-T scanner at 48 hours and 6 months. Myocardial edema was quantified using a T2 mapping technique, and infarct size and microvascular obstruction size were assessed by way of a contrast-enhanced T1-weighted inversion recovery gradient-echo sequence. The infarct segment T2 was elevated in diabetics compared with nondiabetics (59.0 ± 8.0 vs 50.8 ± 3.1 ms, p <0.001) at 48 hours. Multivariate analysis demonstrated that diabetes (p <0.001) and symptom-to-balloon time (p = 0.04) were independent predictors of the degree of acute myocardial edema. Infarct size was nonsignificantly higher in the diabetic group at 48 hours (26.9 ± 9.4% vs 20.1 ± 10.1% of myocardium, p = 0.07) and 6 months (17.1 ± 6.3% vs 13.4 ± 6.1% of myocardium, p = 0.09). Microvascular obstruction size was equivalent in both groups, and there was a trend toward lower myocardial salvage index in diabetics (34.2 ± 11.8 vs 49.6 ± 13.4, p = 0.08). In conclusion, diabetes is associated with increased myocardial edema in the acute phase after primary percutaneous coronary intervention. Our results offer insight into the complex processes that characterize myocardial tissue response to injury in diabetic patients.

The Effect of Percutaneous Coronary Intervention of Chronically Totally Occluded Coronary Arteries on Left Ventricular Global and Regional Systolic Function

BACKGROUND Percutaneous coronary intervention (PCI) is frequently attempted to open chronic total occlusions (CTOs) and restore epicardial coronary flow. Data suggest adverse outcomes in the case of PCI failure. We hypothesized that failure to open a CTO might adversely affect regional cardiac function and promote deleterious cardiac remodelling, and success would improve global and regional cardiac function assessed using cardiac magnetic resonance and velocity vector imaging. METHODS Thirty patients referred for PCI to a CTO underwent cardiac magnetic resonance examination before and after the procedure. Left ventricular function and transmural extent of infarction was assessed in these patients. Regional cardiac function using Velocity Vector Imaging version 3.0.0 (Siemens) was assessed in 20 patients. RESULTS Successful CTO opening (thrombolysis in myocardial infarction 3 flow) occurred in 63% of patients. Left ventricular ejection fraction significantly increased after successful PCI (50 ± 13% to 54 ± 11%; P < 0.01). Global longitudinal strain (GLS) fell significantly in the failed group (Δ = -25 ± 17%; P = 0.02) in contrast with successful PCI in which GLS did not change (Δ 20 ± 32%; P = 0.17). GLS rate followed a pattern similar to GLS (failed, Δ -30 ± 17%; P < 0.01 vs success Δ 25 ± 48%; P = 0.34). In contrast, radial and circumferential strain/strain rate were not different between groups after success/failed PCI. CONCLUSIONS Regional cardiac function assessment using velocity vector imaging showed a significant decline in GLS and GLS rate in patients in whom PCI failed to open a CTO, with no change in global measures of cardiac function.

Evolution of right ventricular function post‐acute ST elevation myocardial infarction

To characterize the evolution of right ventricular (RV) function post‐myocardial infarction (MI), to describe the culprit vessel involved with RV injury and to assess the concordance between RV injury on magnetic resonance imaging (MRI) and RV infarct on electrocardiogram (EKG).

Relation of Mitral Valve Prolapse to Basal Left Ventricular Hypertrophy as Determined by Cardiac Magnetic Resonance Imaging

We aimed to characterize the extent and distribution of focal basal left ventricular (LV) hypertrophy in patients with mitral valve prolapse (MVP). Sixty-three patients (mean age: 58 ± 14 years) with MVP and 20 age-matched normal volunteers (mean age: 53 ± 11 years) were assessed using cardiac magnetic resonance imaging. We compared the ratio of basal to mid end-diastolic wall thickness in both groups and correlated it with clinical and imaging parameters. Of the 63 patients, 44 (70%) had posterior leaflet prolapse, 2 (3%) had anterior leaflet prolapse, and 17 (27%) had bileaflet prolapse. There was a significantly increased ratio of basal to mid-ventricular end-diastolic wall thickness in all segments of the left ventricle in those with MVP compared to the controls. The inferolateral (2.1 vs 1.0, p <0.01) and anterolateral (2.1 vs 1.1) ratios (p <0.01) were the greatest compared to the other myocardial segments. The degree of mitral annular excursion had a strong positive correlation with the degree of hypertrophy (r(2) = 0.81, p <0.01) and was an independent predictor in adjusted multivariate analysis (p <0.0001). Age, body mass index, LV end-diastolic volume index, LV end -systolic volume index, LV stroke volume index, degree of prolapse, and mitral regurgitation volume did not have any significant correlation with the degree of hypertrophy. In conclusion, MVP is associated with concentric basal LV hypertrophy and good correlation between the excursion of the mitral valve annulus and the degree of relative LV hypertrophy suggests that locally increased myocardial function could be responsible for this remodeling.