Steep left ventricle to aortic root angle and hypertrophic obstructive cardiomyopathy: study of a novel association using three-dimensional multimodality imaging

BACKGROUND

Patients with hypertrophic cardiomyopathy (HCM) exhibit a difference in left ventricular outflow tract (LVOT) obstruction, independently of basal septal thickness (BST). Some patients with HCM have a steeper left ventricle to aortic root angle than controls.

OBJECTIVE

To test the predictors of the LV-aortic root angle and the association between LV-aortic root angle and LVOT obstruction using three-dimensional imaging.

PATIENTS

153 consecutive patients with HCM (mean (SD) age 46 (14) years, 68% men) and 62 patients with hypertensive heart disease of the elderly (all >65 years of age, 73 (6) years, 34% men) who underwent whole-heart three-dimensional cardiac magnetic resonance (CMR) angiography (1.5 T) and Doppler echocardiography. Forty-two controls (age 43 (11) years, 38% men) who underwent contrast-enhanced multidetector computed tomography and were free of cardiovascular pathology were also studied.

MAIN OUTCOMES

LV-aortic root angle, BST and maximal non-exercise LVOT gradient were measured in patients with HCM and in hypertensive-elderly patients. Additionally, LV-aortic root angle and BST were measured in controls.

RESULTS

The mean (SD) LV-aortic root angle was significantly different (p<0.001) in the three groups: HCM (134 (10) degrees ), hypertensive-elderly (128 (10) degrees ), control (140 (7) degrees ). There was an inverse correlation between age and LV-aortic root angle in the three groups (all p<0.001): HCM (r = -0.56), hypertensive-elderly (r = -0.35), control (r = -0.48). On univariate analysis, in the HCM group, LV-aortic root angle (beta = -0.34, p<0.001), age (beta = 0.23, p = 0.01) and end-systolic volume index (beta = -0.20, p = 0.02), but not BST (beta = 0.02, p = 0.8), were associated with LVOT gradient. On multivariate analysis, only LV-aortic root angle was associated with LVOT gradient.

CONCLUSIONS

Patients with HCM have a steeper LV-aortic root angle than controls. In patients with HCM, a steeper LV-aortic root angle predicts dynamic LVOT obstruction, independently of BST.

Meta-analysis of diagnostic efficacy of 64-slice computed tomography in the evaluation of coronary in-stent restenosis

We sought to conduct a meta-analysis using available studies to determine the diagnostic efficacy of 64-slice computed tomography (CT) in evaluation of in-stent restenosis (ISR). Sixty-four-slice CT allows optimal noninvasive assessment of coronary artery disease. However, a variety of artifacts limit evaluation of stented coronary segments. We included studies that used 64-slice CT for evaluation of coronary ISR. We pooled efficacy estimates across studies using random-effects models. We identified 14 studies, which included 895 patients (1,447 stents, mean diameter 3.1 mm). Of these, 1,231 (91.4%) stents were adequately assessed by 64-slice CT. Overall sensitivity was 91% (95% confidence interval [CI] 86 to 94), specificity was 91% (95% CI 89 to 92), positive predictive value (PPV) was 68% (95% CI 63 to 73), and negative predictive value (NPV) was 98% (95% CI 97 to 99). The summary receiver operating characteristic curves graph showed a symmetric area under the curve of 0.96. When nonassessable segments were included, overall sensitivity and specificity decreased to 87% (95% CI 81 to 92) and 84% (95% CI 82 to 87), with a PPV of 53% (95% CI 47 to 59) and an NPV of 97% (95% CI 96 to 98), respectively. In conclusion, 64-slice CT detects (high sensitivity and specificity) or excludes ISR (high NPV) with a high degree of confidence; however, precise quantification of ISR is not accurate (low PPV). Efficacy estimates are even lower when nonassessable segments are included. Hence, at this point, stress imaging remains the most acceptable noninvasive technique for diagnosis of ISR.

Safety of gadoversetamide in patients with acute and chronic myocardial infarction

PURPOSE

To assess the safety data from two large, multicenter, phase 2 trials on the use of gadoversetamide (OptiMARK, Tyco Healthcare/Mallinckrodt, St. Louis, MO) as a contrast agent in delayed hyperenhancement magnetic resonance imaging (DE-MRI) in patients with acute and chronic myocardial infarction (MI).

MATERIALS AND METHODS

The study population from both trials comprised 577 patients who were randomly assigned to one of four dose groups (0.05, 0.1, 0.2, or 0.3 mmol/kg) before undergoing DE-MRI. Safety evaluations included physical and electrocardiographic (ECG) examinations. Vital signs, laboratory values, adverse events (AE), and serious adverse events (SAE) were monitored before and after contrast administration.

RESULTS

Of the 577 patients who received gadoversetamide, 124 (21.5%) reported a total of 164 AEs; most were mild (139 AEs; 84.8%) or moderate (25 AEs; 15.2%). ECG-related changes were the most frequent AE. Site investigators judged only eight AEs as likely related to gadoversetamide and only two of the eight as clinically relevant. Further evaluation suggested neither AE was related to gadoversetamide. Two SAEs were reported, but none was judged related to gadoversetamide by the site investigators.

CONCLUSION

Gadoversetamide is safe for use in patients with acute or chronic MI up to a dose of 0.3 mmol/kg.

Automatic computation of left ventricular ejection fraction from spatiotemporal information in cine-SSFP cardiac MR images

PURPOSE

To clinically validate an algorithm that automatically computes left ventricular (LV) ejection fraction (LVEF) using a priori geometric and intrinsic spatiotemporal information from cine steady-state free precession (SSFP) MR images.

MATERIALS AND METHODS

The algorithm was evaluated in 64 subjects (21 healthy volunteers and 43 patients, LVEF 19-71%). Bland-Altman analyses were performed on short-axis slices subdivided into three sections (basal, midcavity, and apical) to assess the impact of morphologic variations on LVEF computation.

RESULTS

The automated algorithm delineated the clinically applicable endocardial boundary in 1011 of 1078 short-axis slices (94%). The bias (mean difference) values computed with clinically unusable contours replaced with hand-drawn equivalents were small for the LV end-diastolic volume (LVEDV, <11 mL/7%), end-systolic volume (LVESV, <7 mL/11%), and LVEF (<1.2%). Moreover, these values were within the limits of interobserver and intraobserver variability of experienced observers (LVEDV, <13 mL/8%; LVESV, <12 mL/17%; and LVEF, <5%). In the end-diastolic phase, the limits of agreement (bias +/- 1.96 SD of difference) were small (<5% LVEDV) in all sections. However, in the end-systolic phase, the limits of agreement were larger for the midcavity (<21% LVESV) and apical (<11% LVESV) slices.

CONCLUSION

This data-driven algorithm can estimate LVEDV, LVESV, and LVEF with a bias that is comparable to the interobserver and intraobserver variability of experienced observers.

Effect of dual-source cardiac computed tomography on patient radiation dose in a clinical setting: comparison to single-source imaging

BACKGROUND

Dual-source computed tomography (DSCT) was introduced with significant hardware and software changes compared with single-source CT (SSCT), resulting in improved temporal resolution (83 ms) and the potential for improved image quality. The effect of these changes on radiation dose requirements for coronary CT angiography in clinical practice has not been investigated.

OBJECTIVE

We evaluated patient radiation dose and image quality of electrocardiogram (ECG)-gated helical techniques, using DSCT compared with SSCT for clinical imaging of the coronary arteries.

METHODS

DSCT data from 160 patients were evaluated; 82 patients (DSCT group 1) were imaged with early software, and 78 patients (DSCT group 2) were imaged with a later software version. Patients imaged with SSCT (n = 124) were the control group. Effective radiation dose values were estimated for all patients. Image noise was measured, and image quality was evaluated on a 5-point scale.

RESULTS

Effective dose values for DSCT group 2 (11.7 +/- 4.0 mSv) were not different from those for SSCT group (10.9 +/- 2.9 mSv); the highest doses, 13.2 +/- 3.2 mSv, were recorded for DSCT group 1 (P < 0.001). A decrease in image noise was observed for DSCT compared with SSCT (P <or= 0.001) as was an increase in image quality (P < 0.01). With optimized DSCT imaging, lower dose values were associated with (1) shorter scan range, (2) lower maximum tube current, and (3) lower fraction of R-R interval receiving maximum tube current.

CONCLUSION

ECG-gated helical DSCT can provide images of the coronary arteries with improved image quality and decreased noise without an increase in radiation dose compared with SSCT in clinical patient groups.

Association of coronary atherosclerosis detected by multislice computed tomography and traditional risk-factor assessment

Framingham risk score is an office-based tool used for long-term coronary heart disease risk stratification. Most acute coronary events occur in association with proximal nonobstructive atherosclerotic plaque. Multislice computed tomography detects both obstructive coronary artery disease (CAD) and proximal atherosclerotic plaque with high accuracy. The association of Framingham risk score with obstructive CAD and proximal atherosclerotic plaque was tested. Coronary multislice computed tomography was performed in 295 patients (61% men, mean age 54 +/- 13 years) without documented CAD referred for evaluation of cardiac symptoms. Framingham risk score was computed and patients were stratified according to 10-year risk (n = 213 [72%] low, n = 74 [25%] intermediate, and n = 8 [3%] high). Obstructive CAD was defined as > or =50% stenosis in > or =1 epicardial coronary artery. Proximal atherosclerotic plaque was defined as calcified or noncalcified plaque in the left main or proximal left anterior descending artery. In the low- and intermediate-Framingham risk score groups, there was a high frequency of proximal atherosclerotic plaque (44% and 75%) and obstructive CAD (16% and 34%), although both findings were more prevalent in the high-Framingham risk score group (63% for atherosclerotic plaque, 88% for obstructive CAD), respectively. Proximal atherosclerotic plaque was noncalcified in approximately 13 of patients. In women (n = 114) and younger (<55 years) patients (n = 148), most (93% and 91%, respectively) had a low Framingham risk score. There were 48 women and 51 younger patients with proximal atherosclerotic plaque, of whom only 40% (in each group) were on statin therapy. In conclusion, of patients with a low and intermediate Framingham risk score, a significant proportion had proximal atherosclerotic plaque or obstructive CAD.

Standardized cardiovascular magnetic resonance imaging (CMR) protocols, society for cardiovascular magnetic resonance: board of trustees task force on standardized protocols

Index

1. General techniques

1.1. Stress and safety equipment

1.2. Left ventricular (LV) structure and function module

1.3. Right ventricular (RV) structure and function module

1.4. Gadolinium dosing module.

1.5. First pass perfusion

1.6. Late gadolinium enhancement (LGE)

2. Disease specific protocols

2.1. Ischemic heart disease

2.1.1. Acute myocardial infarction (MI)

2.1.2. Chronic ischemic heart disease and viability

2.1.3. Dobutamine stress

2.1.4. Adenosine stress perfusion

2.2. Angiography:

2.2.1. Peripheral magnetic resonance angiography (MRA)

2.2.2. Thoracic MRA

2.2.3. Anomalous coronary arteries

2.2.4. Pulmonary vein evaluation

2.3. Other

2.3.1. Non-ischemic cardiomyopathy

2.3.2. Arrhythmogenic right ventricular cardiomyopathy (ARVC)

2.3.3. Congenital heart disease

2.3.4. Valvular heart disease

2.3.5. Pericardial disease

2.3.6. Masses

MR-IMPACT: comparison of perfusion-cardiac magnetic resonance with single-photon emission computed tomography for the detection of coronary artery disease in a multicentre, multivendor, randomized trial

AIMS

To determine in a multicentre, multivendor trial the diagnostic performance for perfusion-cardiac magnetic resonance (perfusion-CMR) in comparison with coronary X-ray angiography (CXA) and single-photon emission computed tomography (SPECT).

METHODS AND RESULTS

Of 241 eligible patients from 18 centres, 234 were randomly dosed with 0.01, 0.025, 0.05, 0.075, or 0.1 mmol/kg Gd-DTPA-BMA (Omniscantrade mark, GE-Healthcare) per stress (0.42 mg/kg adenosine) and rest perfusion study. Coronary artery disease (CAD) was defined as diameter stenosis > or =50% on quantitative CXA. Five CMR and eight SPECT studies (of 225 complete studies) were excluded from analyses due to inadequate quality (three blinded readers scored per modality). The comparison of CMR vs. SPECT was based on receiver operating characteristic (ROC) analysis. Perfusion-CMR at the optimal CM dose (0.1 mmol/kg) had similar performance as SPECT, if only the SPECT studies of the 42 patients with this dose were considered [area under ROC curve (AUC): 0.86 +/- 0.06 vs. 0.75 +/- 0.09 for SPECT, P = 0.12]; however, diagnostic performance of perfusion-CMR was better vs. the entire SPECT population (AUC: 0.67 +/- 0.05, n = 212, P = 0.013).

CONCLUSIONS

In this multicentre, multivendor trial, ROC analyses suggest perfusion-CMR as a valuable alternative to SPECT for CAD detection showing equal performance in the head-to-head comparison. Comparing perfusion-CMR with the entire SPECT population suggests CMR superiority over SPECT, which warrants further evaluation in larger trials.