CME: long-term outcome in asymptomatic patients with severe aortic regurgitation, normal left ventricular ejection fraction, and severe left ventricular dilatation

CARDIOKIN1: Computational Assessment of Myocardial Metabolic Capability in Healthy Controls and Patients With Valve Diseases

Supplemental Digital Content is available in the text.

Background:

Many heart diseases can result in reduced pumping capacity of the heart muscle. A mismatch between ATP demand and ATP production of cardiomyocytes is one of the possible causes. Assessment of the relation between myocardial ATP production (MV_ATP) and cardiac workload is important for better understanding disease development and choice of nutritional or pharmacologic treatment strategies. Because there is no method for measuring MV_ATP in vivo, the use of physiology-based metabolic models in conjunction with protein abundance data is an attractive approach.

METHOD:

We developed a comprehensive kinetic model of cardiac energy metabolism (CARDIOKIN1) that recapitulates numerous experimental findings on cardiac metabolism obtained with isolated cardiomyocytes, perfused animal hearts, and in vivo studies with humans. We used the model to assess the energy status of the left ventricle of healthy participants and patients with aortic stenosis and mitral valve insufficiency. Maximal enzyme activities were individually scaled by means of protein abundances in left ventricle tissue samples. The energy status of the left ventricle was quantified by the ATP consumption at rest (MV_ATP[rest]), at maximal workload (MV_ATP[max]), and by the myocardial ATP production reserve, representing the span between MV_ATP(rest) and MV_ATP(max).

Results:

Compared with controls, in both groups of patients, MV_ATP(rest) was increased and MV_ATP(max) was decreased, resulting in a decreased myocardial ATP production reserve, although all patients had preserved ejection fraction. The variance of the energetic status was high, ranging from decreased to normal values. In both patient groups, the energetic status was tightly associated with mechanic energy demand. A decrease of MV_ATP(max) was associated with a decrease of the cardiac output, indicating that cardiac functionality and energetic performance of the ventricle are closely coupled.

Conclusions:

Our analysis suggests that the ATP-producing capacity of the left ventricle of patients with valvular dysfunction is generally diminished and correlates positively with mechanical energy demand and cardiac output. However, large differences exist in the energetic state of the myocardium even in patients with similar clinical or image-based markers of hypertrophy and pump function.

Registration:

URL: https://www.clinicaltrials.gov; Unique identifiers: NCT03172338 and NCT04068740.

Surrogates for myocardial power and power efficiency in patients with aortic valve disease

We aimed to assess surrogate markers for left ventricular (LV) myocardial power and efficiency in patients with isolated aortic stenosis (AS) and combined stenosis/regurgitation (AS/AR). In AS (n = 59), AS/AR (n = 21) and controls (n = 14), surrogates for LV myocardial power and circulatory/external myocardial efficiency were obtained from cardiac MRI. Median surrogate LV myocardial power was increased in AS, 7.7 W/m² (interquartile range 6.0–10.2; p = 0.010) and AS/AR, 10.8 W/m² (8.9–13.4; p < 0.001) when compared to controls, 5.4 W/m² (4.2–6.5), and was lower in AS than AS/AR (p < 0.001). Surrogate circulatory efficiency was decreased in AS, 8.6% (6.8–11.1; p < 0.001) and AS/AR, 5.4% (4.1–6.2; p < 0.001) when compared to controls, 11.8% (9.8–16.9). Surrogate external myocardial efficiency was higher in AS, 15.2% (11.9–18.6) than in AS/AR, 12.2% (10.1–14.2; p = 0.031) and was significantly lower compared to controls, 12.2% (10.7–18.1) in patients with reduced ejection fraction (EF), 9.8% (8.1–11.7; p = 0.025). In 16% of all cases, left ventricular mass/volume indices and EF were within normal ranges, wheras surrogate LV myocardial power was elevated and patients were symptomatic. Although influenced by pressure/volume load, the myocardium is additionally affected by remodelling processes. Surrogates for circulatory efficiency and LV myocardial power gradually reflect alterations in patients with AS and AS/AR, even when surrogate external myocardial efficiency, EF, mass and volume indices still remain compensated.

Frequency of early remodeling of left ventricle and its comparison between patients with stroke volume ≥97 Ml versus patients with stroke volume <97 Ml after aortic valve replacement for severe aortic regurgitation

Objectives:

To evaluate the frequency of early remodeling in patients of severe aortic regurgitation after aortic valve replacement and to see the incidence of early remodeling in patients with stroke volume >97 ml versus < 97 ml before aortic valve replacement.

Method:

This was a prospective comparative study conducted from August 2013 to December 2014 in a tertiary care hospital. Fifty seven (57) patients of isolated chronic aortic regurgitation were included in this study. SPSS v23 was used for data analysis. Independent sample t-test was used for analysis of continuous variables and chi-square test for qualitative variables.

Results:

Out of fifty seven patients, early remodeling occurred in 34 (59.64%) patients after surgery. The mean pre-operative stroke volume of patient in whom remodeling occurred was 110.3+9.66 ml while mean pre-operative stroke volume of patients who did not undergo remodeling was 86.65+7.63 ml. There were 28 (82.4%) patients with stroke volume >97 ml in whom Remodeling occurred where as in patients with stroke volume <97 ml remodeling occurred only in 6 (17.6%) patients (p value 0.004). There was no in-hospital mortality.

Conclusion:

There is an association between stroke volume and early LV remodeling after Aortic valve replacement. Stroke volume >97 ml is a good predictor of early LV remodeling.

Left ventricular shape and mass impact torsional dynamics in asymptomatic patients with chronic aortic regurgitation and normal left ventricular ejection fraction

Chronic aortic regurgitation (AR) is associated with a unique pattern of left ventricular (LV) volume and pressure overload, leading to LV remodelling. LV torsional motion, a key component of LV performance, can be altered in this setting. We aimed to assess the impact of LV remodelling on LV torsional dynamics parameters using speckle-tracking echocardiography (STE) in asymptomatic AR patients. We prospectively enrolled 60 patients with chronic AR and LVEF > 50% and 55 healthy controls. LV rotation, twisting and untwisting were assessed using STE. Patients with AR had higher LV diameters, volumes and mass, a more spherical LV shape than controls, but similar LVEF. In AR patients we found reduced peak LV apical rotation and decreased (2.1 ± 0.8 vs 2.9 ± 0.9°/cm, p < 0.001) and delayed (time to peak LV twist: 0.94 ± 0.12 vs 0.99 ± 0.09, p = 0.004) peak LV torsion. Also, peak LV untwisting velocity was decreased (-123.5 ± 41.5 vs -152.3 ± 55.0°/s, p = 0.002) due to lower peak LV apical diastolic rotation rate. LV shape influenced LV torsional dynamics, a more spherical LV displaying reduced peak LV apical rotation and diastolic rotation rate and decreased LV twist. A more hypertrophied LV had a lower peak LV torsion, peak LV apical diastolic rotation rate and peak LV untwisting velocity. LV apical rotation and torsion are decreased and LV twist is delayed in patients with chronic AR and normal LVEF, detecting early subclinical LV dysfunction before LVEF declines. Also, LV untwisting is reduced in these patients. LV remodelling impairs LV torsional dynamics parameters in this setting.

Mitral valve enlargement in chronic aortic regurgitation as a compensatory mechanism to prevent functional mitral regurgitation in the dilated left ventricle

OBJECTIVES

The aim of this study was to test the hypothesis that mitral valve (MV) enlargement occurring in chronic aortic regurgitation (AR) prevents functional mitral regurgitation (FMR).

BACKGROUND

Chronic AR causes left ventricular (LV) dilation, creating the potential for FMR. However, FMR is typically absent during compensated AR despite substantial LV enlargement. Increased mitral leaflet area has been identified in AR, but it is unknown whether increased MV size can represent a compensatory mechanism capable of preventing FMR.

METHODS

Database review of 816 patients with at least moderate AR evaluated the prevalence of FMR. A total of 90 patients were enrolled prospectively for 3-dimensional echocardiography (30 AR, 30 FMR, and 30 controls) to assess MV geometry including total leaflet area.

RESULTS

FMR was present in 5.6% of AR patients by database review. Prospectively, only 1 AR patient had more than mild FMR despite increased LV end-diastolic volume (82 ± 22, 86 ± 23, and 51 ± 12 cm(3)/m(2), respectively, for AR, FMR vs. control patients; p < 0.01) and similar sphericity index, annular area, and tethering distances compared with FMR. Total MV area was largest in AR (31.3% greater than normal), increasing significantly more than in FMR. The ratio of valve size to closure area was maintained in AR, whereas decreases in this ratio and LV ejection fraction independently predicted FMR.

CONCLUSIONS

FMR prevalence is low in chronic AR. MV leaflet area is significantly increased compared with control and FMR patients, preserving a normal relationship to the area needed for closure in the dilated LV. Understanding the mechanisms underlying this adaptation could lead to new therapeutic interventions to prevent FMR.

[State of the art: new developments in cardiac imaging]

Cardiac imaging continues to reveal new anatomical and functional insights into heart disease. In echocardiography, both transesophageal and transthoracic three-dimensional imaging have been fully developed and optimized, and the value of the techniques that have increased our understanding of cardiac mechanics and ventricular function is well established. At the same time, the healthcare industry has released new devices onto the market which, although they are easier to use, have limitations that restrict their use for routine assessment. Tomography's diagnostic and prognostic value in coronary artery disease continues to increase while radiation exposure becomes progressively lower. With cardiac magnetic resonance imaging, myocardial injury and recovery in ischemic heart disease and following acute coronary syndrome can be monitored in exquisite detail. The emergence of new combined tomographic and gamma camera techniques, exclusively developed for nuclear cardiology, have improved the quality of investigations and reduced radiation exposure. The hybrid or fusion images produced by combining different techniques, such as nuclear cardiology techniques and tomography, promise an exciting future.