Brenda Hayes

Assessment of Myocardial Scarring Improves Risk Stratification in Patients Evaluated for Cardiac Defibrillator Implantation

OBJECTIVES We tested whether an assessment of myocardial scarring by cardiac magnetic resonance imaging (MRI) would improve risk stratification in patients evaluated for implantable cardioverter-defibrillator (ICD) implantation. BACKGROUND Current sudden cardiac death risk stratification emphasizes left ventricular ejection fraction (LVEF); however, most patients suffering sudden cardiac death have a preserved LVEF, and many with poor LVEF do not benefit from ICD prophylaxis. METHODS One hundred thirty-seven patients undergoing evaluation for possible ICD placement were prospectively enrolled and underwent cardiac MRI assessment of LVEF and scar. The pre-specified primary endpoint was death or appropriate ICD discharge for sustained ventricular tachyarrhythmia. RESULTS During a median follow-up of 24 months the primary endpoint occurred in 39 patients. Whereas the rate of adverse events steadily increased with decreasing LVEF, a sharp step-up was observed for scar size >5% of left ventricular mass (hazard ratio [HR]: 5.2; 95% confidence interval [CI]: 2.0 to 13.3). On multivariable Cox proportional hazards analysis, including LVEF and electrophysiological-study results, scar size (as a continuous variable or dichotomized at 5%) was an independent predictor of adverse outcome. Among patients with LVEF >30%, those with significant scarring (>5%) had higher risk than those with minimal or no (≤5%) scarring (HR: 6.3; 95% CI: 1.4 to 28.0). Those with LVEF >30% and significant scarring had risk similar to patients with LVEF ≤30% (p = 0.56). Among patients with LVEF ≤30%, those with significant scarring again had higher risk than those with minimal or no scarring (HR: 3.9; 95% CI: 1.2 to 13.1). Those with LVEF ≤30% and minimal scarring had risk similar to patients with LVEF >30% (p = 0.71). CONCLUSIONS Myocardial scarring detected by cardiac MRI is an independent predictor of adverse outcome in patients being considered for ICD placement. In patients with LVEF >30%, significant scarring (>5% LV) identifies a high-risk cohort similar in risk to those with LVEF ≤30%. Conversely, in patients with LVEF ≤30%, minimal or no scarring identifies a low-risk cohort similar to those with LVEF >30%.

Anatomic and clinical correlates of septal morphology in hypertrophic cardiomyopathy

UNLABELLED Aim The presence of septal hypertrophy in hypertrophic cardiomyopathy (HCM) is common. To date, there has been no accepted classification of septal morphology in HCM. Furthermore, the possible relationship between septal morphology and clinical features of HCM is undefined. METHODS AND RESULTS Seventy-five consecutive adult patients with HCM were enrolled. Septal morphologies were retrospectively categorized into one of four patterns of hypertrophy based on transthoracic echocardiography. Left ventricular diastolic function by Doppler echocardiography and late gadolinium enhancement (LGE) by magnetic resonance imaging were assessed in all patients. Patients were followed for a mean of 45 ± 32 months. Catenoid septum was the most common morphologic subtype (46 of 75, 61%), followed by simple sigmoid (22 of 75, 29%), neutral (4 of 75, 5%), and apical (3 of 75, 4%). Inter-observer reproducibility of septal classifications was high (κ = 0.95). Patients with the catenoid subtype presented at a younger age, had worse diastolic function, and high rates of LGE. The presence of catenoid septal morphology was independently associated with LGE in multivariable logistic regression analysis. Implantable cardioverter-defibrillator implantation for prevention of sudden cardiac death occurred only in patients with this septal morphology. CONCLUSION We propose a simple, reproducible classification system of patterns of septal hypertrophy in HCM. These patterns of hypertrophy are associated with significant differences in clinical, haemodynamic, and myocardial characteristics. Further studies are needed to evaluate the relationship between septal morphology and outcome or response to therapies in HCM.

CMR adenosine stress perfusion in pediatrics and congenital heart disease: effects on clinical decision making and outcomes

Methods Consecutive patients, who completed CMR adenosine stress perfusion and were 21yo with CHD, were enrolled. SSFP cine and delayed enhancement CMR (DE-CMR) were performed in a standard manner. Adenosine stress perfusion was performed with administration of adenosine (140 ug/kg/min) for 2-4 minutes and gadolinium (0.1 mmol/kg) using a standard adult protocol. Perfusion defects matching infarct size on DECMR and defects corresponding to DE-CMR at the right ventricular insertion site or post-surgical changes were considered negative for ischemia.

Prevalence of myocardial scarring in congenital heart disease - comparison between left ventricular pressure and volume overload using a novel black-blood delayed enhancement imaging technique

Background Congenital heart disease (CHD) can result in left ventricular pressure and/or volume overloaded states, which may result in myocardial scarring. Prior studies have suggested that the presence of myocardial scar may be associated with adverse outcome in patients with CHD. The current gold standard for scar imaging is delayed-enhancement MRI (DE-MRI). However, it may be difficult to distinguish hyperenhanced subendocardial scars from the bright blood-pool with DE-MRI. We have developed a new, Flow-Independent Dark-blood DeLayed Enhancement technique (FIDDLE) that increases the conspicuity of subendocardial hyperenhancement, by making the blood-pool black. In this study we investigated the prevalence of myocardial scarring as determined by DE-MRI and FIDDLE in CHD patients with LV pressure or volume overload.

Relationship between obesity and unrecognized myocardial infarction: a EuroCMR multi-center study

Background Obesity is a major public health issue given its high cardiovascular morbidity and mortality. However, whether obesity predicts cardiovascular disease independent from traditional Framingham risk factors is controversial [1]. Delayed-enhancement CMR (DE-CMR) allows for sensitive and specific detection of unrecognized MI, which appears associated with adverse prognosis similar to clinically recognized MI. We examined the relationship between obesity and the prevalence of unrecognized myocardial scar (UScar) and/ or unrecognized MI (UMI) as determined by DE-CMR.

Application of continuous composite RF pulses as components of a fat-suppressed T2-preparation module for 3 Tesla - evaluation of its fat suppression efficiency in clinical cardiac patients

Background In myocardial T2-imaging, T2-preparation (T2P) is a common mechanism of creating T2-contrast to reveal pathophysiology. Because T2-contrast is often subtle, bright fat signal can hamper image analysis. Combining T2P with fat suppression (FS) is thus advantageous, but fat saturation is frequently inefficient, and fat inversion by Spectral Attenuated Inversion Recovery (SPAIR) requires high power and constrains sequence timing. We created a T2P module with integrated fat inversion by applying the novel concept of continuous composite RF pulses to create tip-down and flip-back components. We compared this module to two existing modules. Our aim was to develop a shorter T2P compatible FS requiring less power and allowing more flexible timing than SPAIR, but with equivalent suppression efficiency.

The incidence of nephrogenic systemic fibrosis in subjects receiving gadoversetamide for cardiovascular magnetic resonance

Summary The incidence of nephrogenic systemic fibrosis in subjects receiving gadoversetamide for cardiovascular magnetic resonance is low (0.026% overall and 1.274% in those subjects with CKD Stage 5 on hemodialysis). Background Since 2006, the US Food and Drug Administration (FDA) has recommended restricting gadolinium based contrast agents (GBCAs) for magnetic resonance in patients with renal impairment due to an association of GBCA use with nephrogenic systemic fibrosis (NSF). The multiple FDA warnings have listed different glomerular filtration rate (GFR) cut-off values for restricting GBCA use. Consequently, hospital policies vary in renal impairment screening criteria and restrictions for both agent-specific and GFR cut-off values for GBCA use. Determining the incidence of developing NSF after exposure to specific GBCAs, and when stratified by chronic kidney disease (CKD) stage, may clarify which agents and patients are at highest risk for developing NSF. Currently, the incidence of developing NSF after exposure to gadoversetamide (Covidien, Mansfield MA) is unknown. The objective of this study was to determine the incidence and patients at highest risk of developing NSF in a large cohort of patients with suspected cardiovascular disease receiving gadoversetamide. Methods

A novel index of infarct morphology predicts the presence of microvascular obstruction in patients with acute myocardial infarction

Background Microvascular obstruction (MO) has been associated with poor LV remodeling and adverse prognosis. Infarct morphology is related to the presence of MO in that patients with MO generally have larger infarct size (IS) and greater mean infarct transmurality. However, neither index is highly predictive on an individual patient basis. In the current study, we investigated the utility of a novel index of infarct morphology, which reflects the circumferential extent of fully transmural infarction extending to the epicardial surfacethe epicar- dial surface area (EpiSA) of infarctionto predict MO. Methods We studied 302 consecutive patients from 2 centers (Duke and Maastricht University) with first AMI. On contrast-enhanced-CMR, early (2-min post-contrast) and late MO (10-min post-contrast) were defined as hypoenhanced regions within hyperenhanced infarction. Infarct size, mean transmurality, and EpiSA were quanti- fied by manual planimetry of the stack of short-axis views. Results Patients were 58±11 years old (71% male). Prevalence of early and late MO was 64% and 55%, respectively. For the population, IS, mean transmurality, and EpiSA were 14% of LV mass (IQR 7-25%), 74% of infarct sector (IQR 57-86%) and 6% of total LV epicardial-surface-area (IQR 1-13%), respectively. All 3 infarct characteristics were significantly larger in patients with MO (all p 42% of LV (4% of population). However, only a small portion of the population (5%+4%=9%) had infarct size reaching these thresholds, showing that IS had limited discrimi- natory value on an individual patient basis. Similarly, infarct transmurality had limited discriminatory value. In contrast, EpiSA thresholds allowed ruling-in or rul- ing-out MO in a significantly larger percentage of the population (44% for both early and late; p<0.0001 com- pared with IS and transmurality). No patient had MO unless EpiSA was greater than zero. Multivariable analy- sis incorporating clinical, ECG, and CMR data demon- strated that EpiSA was the strongest, independent predictor of early and late MO (p<0.0001 for both). Conclusions The epicardial surface area of infarction, a novel index of infarct morphology, is a stronger predictor of MO than infarct size or mean transmurality. MO does not occur unless infarction extends to the epicardial surface.