Early changes in left atrial volume after acute myocardial infarction. Relation to invasive hemodynamics at rest and during exercise

Fine tuning contractility: atrial sarcomere function in health and disease

The molecular mechanisms of sarcomere proteins underlie the contractile function of the heart. Although our understanding of the sarcomere has grown tremendously, the focus has been on ventricular sarcomere isoforms due to the critical role of the ventricle in health and disease. However, atrial-specific or -enriched myofilament protein isoforms, as well as isoforms that become expressed in disease, provide insight into ways this complex molecular machine is fine-tuned. Here, we explore how atrial-enriched sarcomere protein composition modulates contractile function to fulfill the physiological requirements of atrial function. We review how atrial dysfunction negatively affects the ventricle and the many cardiovascular diseases that have atrial dysfunction as a comorbidity. We also cover the pathophysiology of mutations in atrial-enriched contractile proteins and how they can cause primary atrial myopathies. Finally, we explore what is known about contractile function in various forms of atrial fibrillation. The differences in atrial function in health and disease underscore the importance of better studying atrial contractility, especially as therapeutics currently in development to modulate cardiac contractility may have different effects on atrial sarcomere function.

Left Atrial Remodeling Following ST-Segment-Elevation Myocardial Infarction Correlates With Infarct Size and Age Older Than 70 Years

Background Following myocardial infarction, left ventricular remodeling (LVR) is associated with heart failure and cardiac death. At the same time, left atrial (LA) remodeling (LAR) is an essential part of the outcome of a wide spectrum of cardiac conditions. The authors sought to evaluate the correlates of LAR and its relationships with LVR after myocardial infarction. Methods and Results This is a retrospective analysis of 320 of 443 patients enrolled for study of LVR after ST-elevation myocardial infarction. Left ventricular (LV) volumes, infarct size and LA volume index were assessed by cardiac magnetic resonance imaging during index hospitalization (day 6 [interquartile range, 4-8]) and after a 3-month follow-up. LAR was studied using a linear mixed model for repeated measurements. Overall, there was a decrease in LA volume index between 6 days and 3 months (43.9±10.4 mL versus 42.8±11.1 mL, P=0.003). Patients with changes in LA volume index >8% over time were older, with greater body mass index, lower LV ejection fraction, and larger infarct size. Unadjusted predictors of LAR were age older than 70 years, infarct size, anterior infarction, time to reperfusion, history of hypertension, LV end-diastolic volume, and heart failure at day 6. Independent correlates were age older than 70 years (3.24±1.33, P=0.015) and infarct size (2.16±0.72 per 10% LV, P<0.001). LA remodeling was correlated with LV remodeling (r=0.372, P<0.001), but neither LA nor LV volumes at day 6 were related to LVR or LAR, respectively. Conclusions The authors found LA changes to occur in the months after myocardial infarction, with an overall decrease in LA volumes. While LAR coincided with LVR, the correlates for LAR were age older than 70 years and larger infarct size.

Isolated diastolic dysfunction is associated with increased mortality in critically ill patients

PURPOSE

Left ventricular (LV) diastolic dysfunction is important in critically ill patients, but prevalence and impact on mortality is not well studied. We classified intensive care patients with normal left ventricular function according to current diastolic guidelines and explored associations with mortality.

MATERIAL AND METHODS

Echocardiography was performed within 24 h of intensive care admission. Patients with reduced LV ejection fraction, regional wall motion abnormality, or a history of cardiac disease were excluded. Patients were classified according to the 2016 EACVI guidelines, Recommendations for the Evaluation of LV Diastolic Function by Echocardiography.

RESULTS

Out of 218 patients, 162 (74%) had normal diastolic function, 21 (10%) had diastolic dysfunction, and 35 (17%) had indeterminate diastolic function. Diastolic dysfunction were more common in female patients, older patients and associated with sepsis, respiratory and cardiovascular comorbidity as well as higher SAPS Score. In a risk-adjusted logistic regression model, patients with indeterminate diastolic dysfunction (OR 4.3 [1.6-11.4], p = 0.004) or diastolic dysfunction (OR 5.1 [1.6-16.5], p = 0.006) had an increased risk of death at 90 days compared to patients with normal diastolic function.

CONCLUSION

Isolated diastolic dysfunction, assessed by a multi-parameter approach, is common in critically ill patients and is associated with mortality.

TRIAL REGISTRATION

Secondary analysis of data from a single-center prospective observational study focused on systolic dysfunction in intensive care unit patients (Clinical Trials ID: NCT03787810.

Effect of Infarct Location and Size on Left Atrial Function: A Cardiovascular Magnetic Resonance Feature Tracking Study

Background: LA function has been recognized as a significant prognostic marker in many cardiovascular diseases. Cardiovascular magnetic resonance feature tracking (CMR-FT) represents a promising technique for left atrial function evaluation. The size and location of myocardial infarction are important factors in the cause of adverse left ventricular remodeling, but the effect on the left atriam is unclear. Purpose: to investigate the effect of location and size of previous myocardial infarction (MI) on LA function using CMR-FT. Study type: retrospective. Population: patients formerly diagnosed with anterior MI (n = 42) or non-anterior MI (n = 40) and healthy controls (n = 47). Field Strength/Sequence: a 3.0T MR, Steady state free precession (SSFP), Phase-sensitive inversion recovery (PSIR). Assessment: infarct location and size were assigned and quantified by late-gadolinium enhancement (LGE) imaging. LA performance was analyzed using CMR-FT in 2- and 4-chamber cine images, including LA reservoir, conduit and booster pump function. Statistics: descriptive statistics, ANOVA with post Bonferroni correction, Kruskal−Wallis H, Spearman’s correlation, intraclass correlation coefficient. Results: Anterior MI patients had impaired LA reservoir function (LATEF, εs, SRs), conduit function (LAPEF, εe, SRs) and booster pump function (LAAEF, εa) compared with controls (p < 0.05). Non-anterior MI patients had impaired LA strain (εs, εe, εa; p < 0.05) but preserved LAEFs (p > 0.05). After adjusting the area of MI, there was no significant difference in the LA morphology and function between the anterior and non-anterior wall groups. Stratification analysis by MI size revealed that LA volumes and LAEFs were unchanged in patients with MI size ≤ 15% compared with controls (p > 0.05); only εs and εe were decreased (p < 0.05). Increased LAVIpre-a, LAVImin and decreased LATEF, and LAAEF were found in patients with MI size > 15% compared with the MI size ≤ 15% group (p < 0.05). LVSVI, εs and MI size were significant correlated with LAVI pre-a in multiple stepwise regression analysis. Data conclusions: The location of myocardial infarction is not a major factor affecting the morphology and function of the left atrium. Patients with MI size > 15% experience more pronounced post-infarction LA remodeling and dysfunction than MI size ≤ 15% patients.

Changes in left ventricular filling parameters before and after dialysis in patients with end stage renal disease

The aim of this study was to investigate the grading of diastolic dysfunction (DD) in relation to hemodialysis in patients with end stage renal disease (ESRD) on hemodialysis (HD) Cardiovascular disease is prevalent in patients with ESRD and accounts for significant morbidity and mortality. Left ventricular hypertrophy (LVH) is common in ESRD but little is known about the impact of HD on currently recommended grading schemes for DD. Comprehensive echocardiographic data was obtained in consecutive patients with ESRD before (n = 247) and immediately after (n = 239) standard HD regimen. Grading of DD was performed according to current recommendations both pre- and post HD. Prior to HD, DD was classified as present in 83 patients (34%), indeterminate in 51 patients (21%) and absent in 113 patients (45%). Patients with DD at baseline compared to those without were older [67.3 years (13.1) vs. 63.2 (14.3), p = 0.037], were more likely to have diabetic- or hypertensive ESRD (43.4% vs. 35.4%, p = ns) and LVMi was significantly higher [119 g/cm² (27.5) vs. 103 g/cm² (24.3), p < 0.001]. After HD [mean HD time = 221 min (27.6), mean ultrafiltration volume = 2 L (1.1)], 39 patients (16%) exhibited sustained DD. These patients were older [69.4 years (14.5) vs. 65.0 years (13.9), p = 0.071], were more likely to have diabetic- or hypertensive ESRD (59% vs. 36%, p = 0.010). Myocardial adverse remodeling was more advanced with higher LVMi [127.4 g/m² (27.5) vs. 106.5 g/m² (25.3), p < 0.001], lower LVEF [44.7% (11.0) vs. 54.5% (8.7), p < 0.001] and more impaired GLS [- 13.4% (4.3) vs. - 15.8% (4.0), p = 0.006]. Echocardiographic evaluation of diastolic function in patients with ESRD on HD is critically dependent on timing relative to dialysis. The presence of sustained DD after volume unloading by HD identifies a population of patients with an adverse phenotype of blunted vascular response and severe cardiac remodeling.

Protective Effects of Baicalin on Experimental Myocardial Infarction in Rats

Objective

This study aimed to investigate the protective effects of baicalin on myocardial infarction in rats and explore the related mechanisms.

Methods

Fifty Sprague Dawley rats were randomly divided into the control, model, and low-, medium- and high-dose baicalin groups. The latter 3 groups were intraperitoneally injected with baicalin, with a dose of 12.5, 25 and 50 mg/kg, respectively. Then, the myocardial infarction model was established. The hemodynamic of rats was tested, the serum lactate dehydrogenase (LDH), creatine kinase-MB (CK-MB), prostacyclin (PGI₂) and thromboxane A₂ (TXA₂) were determined, the myocardial superoxide dismutase (SOD) and malondialdehyde (MDA) levels were detected, and the myocardial B-cell lymphoma-2 (Bcl-2) and Bcl-2 associated X (Bax) protein expressions were determined.

Results

Compared with the model group, in the high-dose baicalin group the ST segment height and LVEDP were significantly decreased (P<0.05), the LVSP was significantly increased (P<0.05), the serum LDH, CK-MB and TXA2 levels were significantly decreased (P<0.05), the PGI₂ level was significantly increased (P<0.05), the myocardial SOD level was significantly increased (P<0.05), and the myocardial MDA level was significantly decreased (P<0.05); the myocardial Bcl-2 protein level was significantly increased, and the Bax protein level was significantly decreased (P<0.05).

Conclusion

Baicalin has protective effects on myocardial infarction in rats. The possible mechanisms may be related to its resistance to oxidative stress, and up-regulation of Bcl-2 protein expression and down-regulation of Bax protein expression in myocardial tissue.

Practical approach to diastolic dysfunction in light of the new guidelines and clinical applications in the operating room and in the intensive care

There is growing evidence both in the perioperative period and in the field of intensive care (ICU) on the association between left ventricular diastolic dysfunction (LVDD) and worse outcomes in patients. The recent American Society of Echocardiography and European Association of Cardiovascular Imaging joint recommendations have tried to simplify the diagnosis and the grading of LVDD. However, both an often unknown pre-morbid LV diastolic function and the presence of several confounders-i.e., use of vasopressors, positive pressure ventilation, volume loading-make the proposed parameters difficult to interpret, especially in the ICU. Among the proposed parameters for diagnosis and grading of LVDD, the two tissue Doppler imaging-derived variables e' and E/e' seem most reliable. However, these are not devoid of limitations. In the present review, we aim at rationalizing the applicability of the recent recommendations to the perioperative and ICU areas, discussing the clinical meaning and echocardiographic findings of different grades of LVDD, describing the impact of LVDD on patients' outcomes and providing some hints on the management of patients with LVDD.

Midregional pro-atrial natriuretic peptide is a superior biomarker to N-terminal pro-B-type natriuretic peptide in the diagnosis of heart failure patients with preserved ejection fraction

OBJECTIVES

To explore that if mid-regional sequence of pro-A-type natriuretic peptide (MR-proANP) may have a good value of diagnosis in heart failure with preserved ejection fraction (HFpEF) compared with N-terminal pro-B-type natriuretic peptide (NT-proBNP).

METHODS

Participants with cardiovascular disease who were enrolled in this study were divided into the nonheart failure (non-HF) group (n = 75), HFpEF group (n = 65), and HF with reduced ejection fraction (HFrEF) group (n = 50). The MR-proANP and NT-proBNP levels in plasma from all patients were measured by enzyme-linked immunosorbent assay.

RESULTS

The plasma levels of MR-proANP and NT-proBNP in HFpEF and HFrEF groups were higher than those in non-HF group (P < .05). MR-proANP levels were significantly different (P < .05) in different New York Heart Association class patients with HFpEF. In the diagnostic analysis area under the curve of MR-proANP (0.844) was higher than that of NT-proBNP (0.518, P < .001). The left atrial volume index in the HFrEF group was higher than HFpEF group (P < .05); however, both of these groups had a higher index than non-HF group (P < .05).

CONCLUSION

Results indicated that MR-proANP may be more sensitive and specific than NT-proBNP in diagnosing HFpEF. It may be used as a potential diagnostic biomarker in patients with HFpEF.