David Verhaert

Direct T2 Quantification of Myocardial Edema in Acute Ischemic Injury

OBJECTIVES To evaluate the utility of rapid, quantitative T2 mapping compared with conventional T2-weighted imaging in patients presenting with various forms of acute myocardial infarction. BACKGROUND T2-weighted cardiac magnetic resonance (CMR) identifies myocardial edema before the onset of irreversible ischemic injury and has shown value in risk-stratifying patients with chest pain. Clinical acceptance of T2-weighted CMR has, however, been limited by well-known technical problems associated with existing techniques. T2 quantification has recently been shown to overcome these problems; we hypothesized that T2 measurement in infarcted myocardium versus remote regions versus zones of microvascular obstruction in acute myocardial infarction patients could help reduce uncertainty in interpretation of T2-weighted images. METHODS T2 values using a novel mapping technique were prospectively recorded in 16 myocardial segments in 27 patients admitted with acute myocardial infarction. Regional T2 values were averaged in the infarct zone and remote myocardium, both defined by a reviewer blinded to the results of T2 mapping. Myocardial T2 was also measured in a group of 21 healthy volunteers. RESULTS T2 of the infarct zone was 69 ± 6 ms compared with 56 ± 3.4 ms for remote myocardium (p < 0.0001). No difference in T2 was observed between remote myocardium and myocardium of healthy volunteers (56 ± 3.4 ms and 55.5 ± 2.3 ms, respectively, p = NS). T2 mapping allowed for the detection of edematous myocardium in 26 of 27 patients; by comparison, segmented breath-hold T2-weighted short tau inversion recovery images were negative in 7 and uninterpretable in another 2 due to breathing artifacts. Within the infarct zone, areas of microvascular obstruction were characterized by a lower T2 value (59 ± 6 ms) compared with areas with no microvascular obstruction (71.6 ± 10 ms, p < 0.0001). T2 mapping provided consistent high-quality results in patients unable to breath-hold and in those with irregular heart rhythms, in whom short tau inversion recovery often yielded inadequate imaging. CONCLUSIONS Quantitative T2 mapping reliably identifies myocardial edema without the limitations encountered by T2-weighted short tau inversion recovery imaging, and may therefore be clinically more robust in showing acute ischemic injury.

Improved Detection of Myocardial Involvement in Acute Inflammatory Cardiomyopathies Using T2 Mapping

Background— T2-weighted cardiac magnetic resonance imaging is useful in diagnosing acute inflammatory myocardial diseases, such as myocarditis and tako-tsubo cardiomyopathy (TTCM). We hypothesized that quantitative T2 mapping could better delineate myocardial involvement in these disorders versus T2-weighted imaging. Methods and Results— Thirty patients with suspected myocarditis or TTCM, referred for cardiac magnetic resonance imaging, who met established diagnostic criteria underwent myocardial T2 mapping. T2 values were averaged in involved and remote myocardial segments, both defined by a reviewer blinded to T2 data. In myocarditis, T2 was 65.2±3.2 ms in the involved myocardium versus 53.5±2.1 ms in the remote myocardium (P<0.001). In TTCM, T2 was 65.6±4.0 ms in the involved myocardium versus 53.6±2.7 ms in the remote segments (P<0.001). T2 values were similar across remote myocardial segments in patients and all myocardial segments in controls (P>0.05 for all). T2 maps provided diagnostic data even in patients with difficulty breath holding. A T2 cutoff of 59 ms identified areas of myocardial involvement, with sensitivity and specificity of 94% and 97%, respectively. T2 mapping revealed regions of abnormal T2 beyond those identified by wall motion abnormalities or late gadolinium-enhancement positivity. Conventional T2-weighted short tau inversion recovery images were uninterpretable in 7 patients because of artifact and unremarkable in 2 patients who had elevated T2 values. T2-prepared steady-state–free precession images showed areas of signal hyperintensity in only 17 of 30 patients. Conclusions— Quantitative T2 mapping reliably identifies myocardial involvement in patients with myocarditis and TTCM. T2 mapping delineated a greater extent of myocardial disease in both conditions compared with that identified by wall motion abnormalities, T2-weighted short tau inversion recovery imaging, T2-prepared steady-state–free precession, or late gadolinium enhancement. Quantitative T2 mapping warrants consideration as a robust technique to identify myocardial injury in patients with acute myocarditis or TTCM.

The Role of Multimodality Imaging in the Management of Pericardial Disease

Received November 12, 2009; accepted March 19, 2010. Pericardial pathology is commonly encountered in clinical practice and may present either as an isolated process or in association with other systemic disorders. Recognizing pericardial pathology can be relatively straightforward, particularly if the clinical manifestation is typical (eg, the patient with acute pericarditis and an audible friction rub reporting retrosternal pain, exacerbated by inspiration or in the supine position) or when an associated disease process gives a direct clue to the diagnosis (eg, the finding of a complex pericardial effusion in a patient with a known malignancy). In these situations, the diagnostic pathway can be limited to a relatively small sequence of tests to basically confirm the initial clinical suspicion.1 However, pericardial disease can also result in nonspecific symptoms and equivocal physical findings. When the initial tests of choice turn out to be nondiagnostic or the course of the disease is prolonged, pericardial disease may cause considerable diagnostic dilemmas. Furthermore, established diagnostic techniques may not visualize the full extent of the pericardial disease process. In such difficult clinical situations, an integrated multimodality imaging approach may provide incremental value. Unfortunately, current guidelines do not address the role of a multimodality approach in the difficult to manage pericardial patient.1 This review will therefore discuss the potential role of different imaging modalities in the diagnosis and management of pericardial disorders, with a specific focus on what constitutes a rational multimodality imaging approach. The 3 imaging modalities most commonly used for evaluation of pericardial disease are echocardiography, cardiac computed tomography (CT), and cardiac MRI (CMR). The main indications and limitation for each test are summarized in Table 1. Echocardiography remains the initial imaging method of choice for the majority of patients with pericardial disease, but in many clinical scenarios, a transthoracic echocardiogram (TTE) …

Characterization of super-response to cardiac resynchronization therapy.

BACKGROUND In patients with chronic systolic heart failure who undergo cardiac resynchronization therapy (CRT), improvements in left ventricular ejection fraction (LVEF) and reductions in left ventricular volume are generally modest. A minority of patients experience a dramatic response to CRT (super-responders), but the attributes associated with these patients have not been fully characterized. OBJECTIVE The purpose of this study was to identify baseline clinical attributes of super-responders and to assess the survival benefit associated with this response. METHODS We reviewed clinical, echocardiographic, and ECG data from a cohort of 233 patients undergoing new implantation of a CRT device between December 2001 and November 2006. All patients had a baseline LVEF < or =40% and New York Heart Association class II to IV symptoms on standard medical therapy. Patients whose absolute LVEF improved by > or =20% were termed super-responders. A multivariate model was constructed to determine factors predictive of super-response, and an assessment of mortality was made. RESULTS In this cohort of 233 patients, 32 (13.7%) met criteria for super-response. In univariate analysis, super-responders were more likely to be female and have a native left bundle branch block, lower preimplant brain natriuretic peptide and red cell distribution width levels, and smaller baseline left ventricular volumes with trends toward having more nonischemic cardiomyopathy and midventricular lead positions. In multivariate analysis, only left bundle branch block remained significantly associated with super-response. Super-responders had a considerably lower incidence of mortality compared to non-super-responders (9.4% vs 43.2%, P = .006) at mean follow-up of 5.5 +/- 1.2 years. CONCLUSION Baseline left bundle branch block is strongly associated with super-response to CRT. Super-responders derive better long-term outcomes with CRT than do non-super-responders.

Right Ventricular Response to Intensive Medical Therapy in Advanced Decompensated Heart Failure

Background—Right ventricular (RV) systolic dysfunction is a strong predictor of adverse outcomes in heart failure, yet quantitatively assessing the impact of therapy on this condition is difficult. Our objective was to compare the clinical significance of changes in RV echocardiographic indices in response to intensive medical treatment in patients admitted to the hospital with acute decompensated heart failure (ADHF). Methods and Results—Serial comprehensive echocardiography was performed in 62 consecutive patients with ADHF, and adverse events (death, cardiac transplantation, assist device, heart failure rehospitalization) were prospectively documented. RV peak systolic strain was assessed using speckle-tracking longitudinal strain analysis as the average of the basal, mid-, and apical segment of the RV free wall. Other conventional parameters of RV function (RV fractional area change, RV myocardial performance index, tricuspid annular peak systolic excursion, and tissue Doppler peak tricuspid annular systolic velocity) were measured for comparison. In our study cohort [left ventricular ejection fraction, 26±10%; cardiac index, 2.0±0.6 L/(min · m2)], overall mean RV peak systolic strain was −14±4% at baseline and −15±4% at 48 to 72 hours (P=0.27). Among all the RV functional indices measured, only RV peak systolic strain at 48 to 72 hours was associated with adverse events (P=0.02). In particular, improvement in RV peak systolic strain after intensive medical treatment was associated with lower adverse events in this patient population (26% versus 78%; hazard ratio, 0.13; 95% CI, 0.02 to 0.84; P=0.02). Conclusion—Dynamic improvement in RV mechanics in response to intensive medical therapy was associated with lower long-term adverse events in patients with ADHF than in patients not showing improvement.

Feasibility, accuracy, and reproducibility of real-time full-volume 3D transthoracic echocardiography to measure LV volumes and systolic function: a fully automated endocardial contouring algorithm in sinus rhythm and atrial fibrillation.

OBJECTIVES To assess the feasibility, accuracy, and reproducibility of real-time full-volume 3-dimensional transthoracic echocardiography (3D RT-VTTE) to measure left ventricular (LV) volumes and ejection fraction (EF) using a fully automated endocardial contouring algorithm and to identify and automatically correct the contours to obtain accurate LV volumes in sinus rhythm and atrial fibrillation (AF). BACKGROUND 3D transthoracic echocardiography is not used routinely to quantify LV volumes and EF. A fully automated workflow using RT-VTTE may improve clinical adoption. METHODS RT-VTTE was performed and 3D EF and volumes obtained using an automated trabecular endocardial contouring algorithm; an automated correction was applied to track the compacted myocardium. Cardiac magnetic resonance (CMR) and 2-dimensional biplane Simpson method were the reference standard. RESULTS Ninety-one patients (67 in normal sinus rhythm [NSR], 24 in AF) were included. Among all NSR patients, there was excellent correlation between RT-VTTE and CMR for end-diastolic volume (EDV), end-systolic volume (ESV), and EF (r = 0.90, 0.96, and 0.98, respectively; p < 0.001). In patients with EF ≥50% (n = 36), EDV and ESV were underestimated by 10.7 ± 17.5 ml (p = 0.001) and by 4.1 ± 6.1 ml (p < 0.001), respectively. In those with EF <50% (n = 31), EDV and ESV were underestimated by 25.7 ± 32.7 ml (p < 0.001) and by 16.2 ± 24.0 ml (p = 0.001). Automated contour correction to track the compacted myocardium eliminated mean volume differences between RT-VTTE and CMR. In patients with AF, LV volumes and EF were accurate by RT-VTTE (r = 0.94, 0.94, and 0.91 for EDV, ESV, and EF, respectively; p < 0.001). Automated 3D LV volumes and EF were highly reproducible. CONCLUSIONS Rapid, accurate, and reproducible EF can be obtained by RT-VTTE in NSR and AF patients by using an automated trabecular edge contouring algorithm. Furthermore, automated contour correction to detect the compacted myocardium yields accurate and reproducible 3D LV volumes.

Long-Term Reverse Remodeling With Cardiac Resynchronization Therapy: Results of Extended Echocardiographic Follow-Up

OBJECTIVES The purpose of this study was to describe the long-term course of left ventricular remodeling induced by cardiac resynchronization therapy (CRT), adjusting for the confounding effect of patient loss due to disease. BACKGROUND Reverse remodeling has been identified as the primary mechanism of improved symptoms and outcome in heart failure patients. METHODS A total of 313 consecutive patients who underwent CRT with available baseline echocardiograms and subsequent clinical and echocardiographic follow-up were included in the analysis. Long-term follow-up included all-cause mortality, heart transplantation, and implantation of a left ventricular assist device. Longitudinal data analysis of left ventricular end-systolic volume index (LVESVi) was performed to adjust for the confounding effect of patient loss during follow-up. RESULTS Patients with uneventful survival had a lower baseline LVESVi (Delta = 8.6 ml/m(2), SE = 4.6 ml/m(2), p < 0.0001) and a decreased LVESVi by -0.11 ml/m(2)/day during first 6 months, whereas the LVESVi remained unchanged in patients with adverse events (p < 0.0001). Beyond 6 months, the LVESVi remained unchanged in patients with uneventful survival, whereas the LVESVi continued to increase in those with adverse events at a rate of 0.01 ml/m(2)/day (p < 0.0001). Predictors of reverse remodeling were nonischemic etiology, female sex, and a wider QRS duration (p < 0.0001, p = 0.014, and p = 0.001, respectively). In the majority of patients, 6 months indicates a break point after which reverse remodeling becomes significantly less pronounced. CONCLUSIONS CRT patients with uneventful survival show a significant decrease in the LVSVi at 6 months and generally maintain this response in the long term. Those with adverse outcomes are characterized by left ventricular dilation despite CRT.

Comparison of severity of aortic regurgitation by cardiovascular magnetic resonance versus transthoracic echocardiography.

Transthoracic echocardiography is the current standard for assessing aortic regurgitation (AR). AR severity can also be evaluated by flow measurement in the ascending aorta using cardiac magnetic resonance (CMR); however, the optimal site for flow measurement and the regurgitant fraction (RF) severity grading criteria that best compares with the transthoracic echocardiographic assessment of AR are not clear. The present study aimed to determine the optimal site and RF grading criteria for AR severity using phase-contrast flow measurements and CMR. A prospective observational study was performed of 107 consecutive patients who were undergoing CMR of the thoracic aorta. Using CMR, the AR severity and aortic dimensions were measured at 3 levels in the aorta (the sinotubular junction, mid-ascending aorta, and distal ascending aorta). The results were compared to the transthoracic echocardiographic grade of AR severity using multiple qualitative and quantitative criteria (grade 0, none; I+, mild; II+, mild to moderate; III+, moderate to severe; and IV+, severe). The mean RF values were significantly greater at the sinotubular junction than at the distal ascending aorta (13 ± 13.3% vs 9.4 ± 12.6%, respectively; p <0.001). The RF values that best defined AR severity using phase-contrast CMR were as follows: grade 0 to I+, <8%; grade II+, 8% to 19%; grade III+, 20 to 29%; and grade IV+, 30%) at the sinotubular or mid-ascending aorta. In conclusion, the quantitative RF values of AR severity using phase-contrast flow are best assessed in the proximal ascending aorta and differ from recognized quantitative echocardiographic criteria.

Simultaneous Right and Left Heart Real-Time, Free-Breathing CMR Flow Quantification Identifies Constrictive Physiology

OBJECTIVES The purpose of this study was to evaluate the ability of a novel cardiac magnetic resonance (CMR) real-time phase contrast (RT-PC) flow measurement technique to reveal the discordant respirophasic changes in mitral and tricuspid valve in flow indicative of the abnormal hemodynamics seen in constrictive pericarditis (CP). BACKGROUND Definitive diagnosis of CP requires identification of constrictive hemodynamics with or without pericardial thickening. CMR to date has primarily provided morphological assessment of the pericardium. METHODS Sixteen patients (age 57 ± 13 years) undergoing CMR to assess known or suspected CP and 10 controls underwent RT-PC that acquired simultaneous mitral valve and tricuspid valve inflow velocities over 10 s of unrestricted breathing. The diagnosis of CP was confirmed via clinical history, diagnostic imaging, cardiac catheterization, intraoperative findings, and histopathology. RESULTS Ten patients had CP, all with increased pericardial thickness (6.2 ± 1.0 mm). RT-PC imaging demonstrated discordant respirophasic changes in atrioventricular valve inflow velocities in all CP patients, with mean ± SD mitral valve and tricuspid valve inflow velocity variation of 46 ± 20% and 60 ± 15%, respectively, compared with 16 ± 8% and 24 ± 11% in patients without CP (p < 0.004 vs. patients with CP for both) and 17 ± 5% and 31 ± 13% in controls (p < 0.001 vs. patients with CP for both). There was no difference in atrioventricular valve inflow velocity variation between patients without CP compared with controls (p > 0.3 for both). Respiratory variation exceeding 25% across the mitral valve yielded a sensitivity of 100%, a specificity of 100%, and an area under the receiver-operating characteristic curve of 1.0 to detect CP physiology. Using a cutoff of 45%, variation of transtricuspid valve velocity had a sensitivity of 90%, a specificity of 88%, and an area under the receiver-operating characteristic curve of 0.98. CONCLUSIONS Accentuated and discordant respirophasic changes in mitral valve and tricuspid valve inflow velocities characteristic of CP can be identified noninvasively with RT-PC CMR. When incorporated into existing CMR protocols for imaging pericardial morphology, RT-PC CMR provides important hemodynamic evidence with which to make a definite diagnosis of CP.

Impact of Mitral Regurgitation on Reverse Remodeling and Outcome in Patients Undergoing Cardiac Resynchronization Therapy

Background— Mitral regurgitation (MR) is associated with reduced survival in patients with chronic heart failure, but may be improved with cardiac resynchronization therapy (CRT). We sought to evaluate the relationship between serial measurements of functional MR and reverse remodeling and outcomes in patients undergoing CRT. Methods and Results— A total of 266 consecutive patients undergoing CRT with available baseline echocardiograms and subsequent clinical and echocardiographic follow-up were included in the analysis. Long-term follow-up included all-cause mortality, heart transplantation, and implantation of a left ventricular (LV) assist device. Temporal changes in MR severity and LV end-systolic volume index (LVESVi) were evaluated by linear mixed-model analysis. CRT led to an immediate sustained decrease in MR (P<0.0001), with no significant subsequent change. The amount of MR decrease correlated with a greater decrease in LVESVi late (P⩽0.0001), but not early (P=0.14), after CRT began. Patients with severe MR before CRT experienced a larger LVESVi decrease (P=0.005). Although baseline MR severity was not associated with adverse events (P=0.13), a larger MR decrease (P=0.001) and a smaller residual MR after the initial 6 months of CRT (P=0.03) were predictive of better outcome in a multivariable model. Conclusions— Early reversal of functional MR was associated with reverse cardiac remodeling and improved outcomes. Patients with moderately severe to severe MR before CRT experienced relatively more reverse remodeling than patients with lesser degrees of MR.