Myocardial steatosis impairs left ventricular diastolic-systolic coupling in healthy humans

Contributors to high left ventricular ejection fraction in women with ischemia and no obstructive coronary artery disease: Results from the Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction (WISE-CVD) Study

BACKGROUND

There are sex differences in left ventricular ejection fraction (LVEF) relevant to prognosis where women experience greater mortality at relatively higher LVEF compared to men, yet mechanistic understanding of this adverse prognosis is limited. Women with suspected ischemia with no obstructive coronary disease (INOCA) develop heart failure with preserved ejection fraction (HFpEF), yet contributors to LVEF remain largely unknown.

METHODS

In 370 women with suspected ischemia with no obstructive coronary disease (INOCA) who prospectively underwent cardiac magnetic resonance imaging (CMRI), we investigated the contributions of LV morphology, function, and myocardial perfusion reserve on LVEF using univariate and multiple linear regression.

RESULTS

A majority 71% of participants had high LVEF (>65%), followed by 24% having normal LVEF (55%-65%), and only 5% having low EF (<55%). Baseline characteristics were comparable among the 3 groups, with the exception of age which was 6 years higher in the high LVEF group (P < .01). Women in the high LVEF group also had the lowest LV cavity volume, greatest LV mass-volume ratio, and highest LV end-systolic elastance (all P < .05, adjusted for age, BMI, diabetes, and blood pressure). Myocardial perfusion reserve index was low in all groups (mean MPRI < 2.1) but was not significantly different across the spectrum of LVEF (P = .458).

CONCLUSIONS

Taken together, these data demonstrate that the majority of women with suspected INOCA have elevated LVEF related to smaller, thicker ventricles with greater contractility. Future work is needed to better understand the specific mechanisms driving morphologic and functional changes in women with INOCA, and relations to longer-term HFpEF and mortality.

CLINICAL TRIALS REGISTRATION

NCT02582021.

Human cardiac metabolism

The heart is the most metabolically active organ in the human body, and cardiac metabolism has been studied for decades. However, the bulk of studies have focused on animal models. The objective of this review is to summarize specifically what is known about cardiac metabolism in humans. Techniques available to study human cardiac metabolism are first discussed, followed by a review of human cardiac metabolism in health and in heart failure. Mechanistic insights, where available, are reviewed, and the evidence for the contribution of metabolic insufficiency to heart failure, as well as past and current attempts at metabolism-based therapies, is also discussed.

Mild renal dysfunction causes aggravated cardiac damage in type 2 diabetic patients: a comprehensive echocardiography study

PURPOSE

We sought to detect left ventricular (LV) adverse alterations in structure and function in type 2 diabetes mellitus (T2DM) patients with or without mild renal dysfunction (MRD) using comprehensive echocardiography techniques and to explore the independent risk factors for LV remodeling (LVR) and dysfunction in these patients.

METHODS

The study included 82 T2DM patients with normal LV ejection fraction (presence (n = 42)/absence (n = 40) of MRD). Age- and gender-matched controls (n = 40) were also recruited. LV structure and function were evaluated using conventional echocardiography and three-dimensional speckle tracking echocardiography (3DSTE). Global longitudinal strain (GLS), global circumferential strain (GCS), global area strain (GAS), and global radial strain (GRS) were all measured using 3DSTE.

RESULTS

Compared with the controls with absolute advantage of LV normal geometry, LVR was more frequently present in the two T2DM groups, with the largest proportion in those with T2DM and MRD (P < 0.001). Fasting plasma glucose (FPG) and MRD were both significant risk factors for LVR in T2DM patients. The detection rates of LV diastolic dysfunction and subclinical systolic dysfunction were significantly higher in the T2DM groups than in the controls (P = 0.000). Moreover, the two case groups also showed significantly lower strain values in multiple directions than the controls (all P < 0.05). FPG was significantly associated with LV diastolic dysfunction, whereas FPG and MRD were both significantly associated with subclinical LV systolic dysfunction in T2DM patients.

CONCLUSIONS

The combined use of conventional echocardiography and 3DSTE allowed the timely detection of early cardiac damage in T2DM patients with or without MRD.

Underlying mechanisms and cardioprotective effects of SGLT2i and GLP-1Ra: insights from cardiovascular magnetic resonance

Originally designed as anti-hyperglycemic drugs, Glucagon-Like Peptide-1 receptor agonists (GLP-1Ra) and Sodium-glucose cotransporter-2 inhibitors (SGLT2i) have demonstrated protective cardiovascular effects, with significant impact on cardiovascular morbidity and mortality. Despite several mechanisms have been proposed, the exact pathophysiology behind these effects is not yet fully understood. Cardiovascular imaging is key for the evaluation of diabetic patients, with an established role from the identification of early subclinical changes to long-term follow up and prognostic assessment. Among the different imaging modalities, CMR may have a key-role being the gold standard for volumes and function assessment and having the unique ability to provide tissue characterization. Novel techniques are also implementing the possibility to evaluate cardiac metabolism through CMR and thereby further increasing the potential role of the modality in this context. Aim of this paper is to provide a comprehensive review of changes in CMR parameters and novel CMR techniques applied in both pre-clinical and clinical studies evaluating the effects of SGLT2i and GLP-1Ra, and their potential role in better understanding the underlying CV mechanisms of these drugs.

Myocardial steatosis across the spectrum of human health and disease

Preclinical data strongly suggest that myocardial steatosis leads to adverse cardiac remodelling and left ventricular dysfunction. Using 1 H cardiac magnetic resonance spectroscopy, similar observations have been made across the spectrum of health and disease. The purpose of this brief review is to summarize these recent observations. We provide a brief overview of the determinants of myocardial triglyceride accumulation, summarize the current evidence that myocardial steatosis contributes to cardiac dysfunction, and identify opportunities for further research.