Comparison of left ventricular volumes and ejection fraction by monoplane cineventriculography, unenhanced echocardiography and cardiac magnetic resonance imaging

Valid and Reproducible Quantitative Assessment of Cardiac Volumes by Echocardiography in Patients with Valvular Heart Diseases-Possible or Wishful Thinking?

The analysis of left ventricular function is predominantly based on left ventricular volume assessment. Especially in valvular heart diseases, the quantitative assessment of total and effective stroke volumes as well as regurgitant volumes is necessary for a quantitative approach to determine regurgitant volumes and regurgitant fraction. In the literature, there is an ongoing discussion about differences between cardiac volumes estimated by echocardiography and cardiac magnetic resonance tomography. This viewpoint focuses on the feasibility to assess comparable cardiac volumes with both modalities. The former underestimation of cardiac volumes determined by 2D and 3D echocardiography is presumably explained by methodological and technical limitations. Thus, this viewpoint aims to stimulate an urgent and critical rethinking of the echocardiographic assessment of patients with valvular heart diseases, especially valvular regurgitations, because the actual integrative approach might be too error prone to be continued in this form. It should be replaced or supplemented by a definitive quantitative approach. Valid quantitative assessment by echocardiography is feasible once echocardiography and data analysis are performed with methodological and technical considerations in mind. Unfortunately, implementation of this approach cannot generally be considered for real-world conditions.

The diagnostic accuracy of truncated cardiovascular MR protocols for detecting non-ischemic cardiomyopathies

Cardiovascular magnetic resonance imaging is one of the most important diagnostic modalities in the evaluation of cardiomyopathies. However, significant limitations are the complex and time-consuming workflows and the need of contrast agents. The aim of this multi-center retrospective study was to assess workflows and diagnostic value of a short, contrast agent-free cardiac magnetic resonance protocol. 160 patients from Heidelberg, Germany and 119 patients from Montreal, Canada with suspected cardiomyopathy and 20 healthy volunteers have been enrolled. Scans were performed at a 1.5Tesla or 3Tesla scanner in Heidelberg and at a 3Tesla scanner in Montreal. We used single-slice T1 map only. A stepwise analysis of images has been performed. The possible differential diagnosis after each step has been defined. T1-values and color-encoded T1 maps significantly contributed to the differential diagnosis in 54% of the cases (161/299); the final diagnosis has been done without late gadolinium enhancement images in 83% of healthy individuals, in 99% of patients with dilated cardiomyopathy, in 93% of amyloidosis patients, in 94% of patients with hypertrophic cardiomyopathy and in 85% of patients with hypertensive heart disease, respectively. Comparing the scan time with (48 ± 7 min) vs. without contrast agent (23 ± 5 min), significant time saving could be reached by the short protocol. Subgroup analysis showed the most additional diagnostic value of T1 maps in amyloidosis and hypertrophic cardiomyopathy or in confirmation of normal findings. In patients with unclear left ventricular hypertrophy, a short, non-contrast protocol can be used for diagnostic decision-making, if the quality of the T1 map is diagnostic, even if only one slice is available.

Evaluation of Echocardiographic Measures of Left Ventricular Function in Patients with Duchenne Muscular Dystrophy: Assessment of Reproducibility and Comparison to Cardiac Magnetic Resonance Imaging

BACKGROUND

Patients with Duchenne muscular dystrophy (DMD) require frequent imaging to assess left ventricular (LV) function. Poor imaging windows can limit the diagnostic utility of echocardiography. Cardiac magnetic resonance imaging (CMR) is the gold standard for the assessment of LV function but has not been universally adopted in patients with DMD. The study objectives were (1) to evaluate the reproducibility of echocardiographic measures of LV function, (2) to evaluate which echocardiographic methods correlate best with CMR LV ejection fraction (LVEF), and (3) to evaluate whether CMR provides additional value compared with echocardiography.

METHODS

Twenty-eight participants with DMD prospectively underwent echocardiography and CMR. Two blinded readers measured fractional shortening from M-mode and two-dimensional images and LVEF using four-chamber, biplane Simpson, 5/6 area-length, and three-dimensional methods. Speckle-tracking echocardiography was used to analyze circumferential strain. Readers subjectively rated function and segmental wall motion. Agreement was assessed using intraclass correlation coefficients, Bland-Altman plots, Spearman correlation, and weighted κ.

RESULTS

Two-dimensional fractional shortening and 5/6 area-length LVEF had the best combination of reproducibility and correlation with CMR LVEF, though both misclassified approximately 20% as either normal or abnormal function. Other measures of LV function were less reproducible, with worse correlations with CMR LVEF. Thirty-seven percent of segments not visible on echocardiography were believed to have wall motion abnormalities by CMR.

CONCLUSIONS

Two-dimensional fractional shortening and 5/6 area-length LVEF represent the most accurate and reproducible echocardiographic measures of LV function in patients with DMD. CMR should be considered when neither of these techniques is measurable or when it is necessary to detect more subtle cardiovascular changes.

Cardiac magnetic resonance imaging to assess the impact of maternal habitus on cardiac remodeling during pregnancy

BACKGROUND

It is well known that the maternal cardiovascular system undergoes profound alterations throughout pregnancy. Interest in understanding these changes has led investigators to use evolving and increasingly sophisticated techniques to study these changes, most recently with 2-dimensional echocardiography. Despite its clinical utility, echocardiography has limitations, and cardiac magnetic resonance imaging (CMRI) has become increasingly used for evaluation of cardiac structure and function.

OBJECTIVE

We used CMRI to evaluate cardiac remodeling according to maternal habitus throughout pregnancy and postpartum.

STUDY DESIGN

This was a prospective, observational study of nulliparous women aged 18-30 years, without preexisting medical conditions, conducted from October 2012 through December 2014. Women were classified according to prepregnancy body mass index (BMI) as either normal (BMI 18.5-24.9 kg/m(2)) or overweight (BMI 25-35 kg/m(2)). All women underwent CMRI during 5 epochs throughout gestation: 12-16 weeks, 26-30 weeks, 32-36 weeks, at delivery, and 3 months' postpartum. Using left ventricular mass (LVM) as a marker of cardiac remodeling, the 2 cohorts were compared.

RESULTS

There were 14 normal-weight (BMI 22.2 ± 1.3) and 9 overweight (BMI 29.1 ± 2.0) women who participated in the study. Beginning at 26-30 weeks and continuing to delivery, LVM of both normal-weight and overweight women was significantly increased compared with the respective first-trimester studies for each cohort (P < .001). LVM of both cohorts returned to their index values by 3 months' postpartum. The geometric ratio of LVM to left ventricular end-diastolic volume was calculated, and both normal-weight and overweight women demonstrated concentric remodeling throughout gestation, however this resolved by 12 weeks' postpartum.

CONCLUSION

There is substantial cardiac remodeling during pregnancy with significant increases in LVM that are proportional to maternal size. Left ventricular geometric remodeling was concentric in both normal-weight and overweight women. All changes in cardiac remodeling resolved by 3 months' postpartum.

Clinical Impact of Cardiac Magnetic Resonance Imaging Versus Echocardiography-Guided Patient Selection for Primary Prevention Implantable Cardioverter Defibrillator Therapy

The main eligibility criterion for primary prevention implantable cardioverter defibrillator (ICD) therapy, that is, left ventricular ejection fraction (LVEF), is based on large clinical trials using primarily 2-dimensional echocardiography (2DE). Presently, cardiac magnetic resonance imaging (MRI) is considered the gold standard for LVEF assessment. It has been demonstrated that cardiac MRI assessment results in lower LVEFs compared with 2DE. Consequently, cardiac MRI-LVEF assessment may lead to more patients eligible for ICD implantation with potential clinical consequences. The aim of this study was to evaluate the clinical impact of cardiac MRI-LVEF versus 2DE-LVEF assessment for ICD eligibility. A total of 149 patients with cardiac MRI-LVEF ≤35% referred for primary prevention ICD implantation who underwent both 2DE and cardiac MRI-LVEF assessment were retrospectively included. 2DE-LVEF was computed by Simpson's biplane method. Cardiac MRI-LVEF was computed after outlining the endocardial contours in short-axis cine images. Appropriate device therapy (ADT) and all-cause mortality were evaluated during 2.9 ± 1.7 years of follow-up. The present study found that cardiac MRI-LVEF was significantly lower compared with 2DE-LVEF (23 ± 8% vs 30 ± 8%, respectively, p <0.001), resulting in 29 (19%) more patients eligible for ICD implantation according to the current guidelines (LVEF ≤35%). Patients with 2DE-LVEF >35% but cardiac MRI-LVEF ≤35% experienced a lower ADT rate compared with patients having 2DE-LVEF ≤35% (2.1% vs 10.4% per year, respectively, p = 0.02). Application of cardiac MRI-LVEF cutoff of 30% resulted in 119 eligible patients experiencing 9.9% per year ADT, comparable with 2DE-LVEF cut-off value of 35%. In conclusion, cardiac MRI-LVEF assessment resulted in more patients eligible for ICD implantation compared with 2DE who showed a relatively low event rate during follow-up. The event rate in patients with cardiac MRI-LVEF ≤30% was comparable with patients having a 2DE-LVEF ≤35%. This study suggests the need for re-evaluation of cardiac MRI-based LVEF cut-off values for ICD eligibility.

Classification of diastolic function with phase-contrast cardiac magnetic resonance imaging: validation with echocardiography and age-related reference values

OBJECTIVES

To investigate whether cardiac magnetic resonance phase-contrast imaging (PC-CMR) can determine left ventricular (LV) diastolic function in comparison to echocardiography (EC).

BACKGROUND

Non-invasive evaluation of diastolic function is important for the diagnostic classification and risk stratification of patients with cardiomyopathies. With EC, diastolic function is classified based on the mitral blood flow, LV myocardial tissue Doppler velocities and pulmonary venous flow. PC-CMR has the potential to measure these parameters and may be an important tool to assess diastolic function in clinical routine.

METHODS

In 36 patients with various cardiovascular diseases and 6 healthy volunteers, we performed single-slice short-axis PC-CMR at the level of the mitral leaflet tip and the inflow of the pulmonary veins to generate EC-comparable mitral E and A waves, septal and lateral e' and a' tissue velocities, and E/A and E/e' ratios. EC was performed after PC-CMR in all patients and six volunteers. Patients were classified into three groups of DD for both techniques. In addition, we evaluated 120 healthy volunteers as controls (3 age groups: 1 = 20-35 years; 2 = 36-50 years; 3 ≥ 51 years) for reference values.

RESULTS

PC-CMR correlation with EC regarding the relation of mitral E and A velocities was good (r = 0.83, p < 0.001). The correlation for the mean septal and lateral E/e' ratio was high with r = 0.90 (p < 0.001). 40/42 subjects (95 %) were categorized correctly. The mean scan time for PC-CMR was 189 ± 16 s and mean analysis time was 348 ± 95 s. EC image acquisition time was slightly higher (201 ± 37 s, p = n.s.), whereas EC image analysis time was significantly lower (149 ± 23 s, p < 0.001).

CONCLUSION

The classification of DD with PC-CMR is feasible and shows good agreement with the widely accepted EC classification of DD. We present a practical approach for the clinically important assessment of DD with PC-CMR, circumventing sophisticated and time-consuming CMR sequences and specially designed software analysis tools.

Genetics of melatonin receptor type 2 is associated with left ventricular function in hypertensive patients treated according to guidelines

BACKGROUND

Melatonin exerts multiple biological effects with potential impact on human diseases. This is underscored by genetic studies that demonstrated associations between melatonin receptor type 2 gene (MTNR1B) polymorphisms and characteristics of type 2 diabetes. We set out to test the hypothesis whether genetic variants at MTNR1B are also relevant for other disease phenotypes within the cardiovascular continuum. We thus investigated single nucleotide polymorphisms (SNPs) of MTNR1B in relation to blood pressure (BP) and cardiac parameters in hypertensive patients.

METHODS

Patients (n=605, mean age 56.2±9.4years, 82.3% male) with arterial hypertension and cardiac ejection fraction (EF) ≥40% were studied. Cardiac parameters were assessed by echocardiography.

RESULTS

The cohort comprised subjects with coronary heart disease (73.1%) and myocardial infarction (48.1%) with a mean EF of 63.7±8.9%. Analysis of SNPs rs10830962, rs4753426, rs12804291, rs10830963, and rs3781638 revealed two haplotypes 1 and 2 with frequencies of 0.402 and 0.277, respectively. Carriers with haplotype 1 (CTCCC) showed compared to non-carriers a higher mean 24-hour systolic BP (difference BP: 2.4mmHg, 95% confidence interval (CI): 0.3 to 4.5mmHg, p=0.023). Haplotype 2 (GCCGA) was significantly related to EF with an absolute increase of 1.8% (CI: 0.45 to 3.14%) in carriers versus non-carriers (p=0.009).

CONCLUSION

Genetics of MTNR1B point to impact of the melatonin signalling pathway for BP and left ventricular function. This may support the importance of the melatonin system as a potential therapeutic target.