Impact of Coronary Microvascular Dysfunction on Functional Left Ventricular Remodeling and Diastolic Dysfunction

BACKGROUND

Coronary microvascular dysfunction (CMD) is a common complication of ST-segment-elevation myocardial infarction (STEMI) and can lead to adverse cardiovascular events. Whether CMD after STEMI is associated with functional left ventricular remodeling (FLVR) and diastolic dysfunction, has not been investigated.

METHODS AND RESULTS

This is a nonrandomized, observational, prospective study of patients with STEMI with multivessel disease. Coronary flow reserve and index of microcirculatory resistance of the culprit vessel were measured at 3 months post-STEMI. CMD was defined as index of microcirculatory resistance ≥25 or coronary flow reserve <2.0 with a normal fractional flow reserve. We examined the association between CMD, LV diastolic dysfunction, FLVR, and major adverse cardiac events at 12-month follow-up. A total of 210 patients were enrolled; 59.5% were men, with a median age of 65 (interquartile range, 58-76) years. At 3-month follow-up, 57 patients (27.14%) exhibited CMD. After 12 months, when compared with patients without CMD, patients with CMD had poorer LV systolic function recovery (-10.00% versus 8.00%; P<0.001), higher prevalence of grade 2 LV diastolic dysfunction (73.08% versus 1.32%; P<0.001), higher prevalence of group 3 or 4 FLVR (11.32% versus 7.28% and 22.64% versus 1.99%, respectively; P<0.001), and higher incidence of major adverse cardiac events (50.9% versus 9.8%; P<0.001). Index of microcirculatory resistance was independently associated with LV diastolic dysfunction and adverse FLVR.

CONCLUSIONS

CMD is present in ≈1 of 4 patients with STEMI during follow-up. Patients with CMD have a higher prevalence of LV diastolic dysfunction, adverse FLVR, and major adverse cardiac events at 12 months compared with those without CMD.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique Identifier: NCT05406297.

Cardiac Lymphatic Insufficiency Leads to Diastolic Dysfunction Via Myocardial Morphologic Change

Although cardiac lymphatic vessels have received increasing attention in recent years, there is still a knowledge gap between cardiac lymphatics and heart homeostasis in a normal heart. In the present study, we established a mouse model of cardiac lymphatic insufficiency ablating cardiac lymphatic collector vessels to reveal the crucial role of cardiac lymphatic vessels in maintaining cardiac homeostasis and the impact on cardiac function both in physiological and pathologic settings. Furthermore, therapeutic lymphangiogenesis improved the adverse effect on cardiac morphologic changes and functions. These findings suggest that the cardiac lymphatic system would be a novel therapeutic target for heart disease.

Prognostic Impact of Cardiac Diastolic Function and Coronary Microvascular Function on Cardiovascular Death

Background Coronary microvascular dysfunction (CMD) has been considered as a possible cause of cardiac diastolic dysfunction. The current study evaluated the association between cardiac diastolic dysfunction and CMD, and their prognostic implications in patients without significant left ventricular systolic dysfunction and epicardial coronary stenosis. Methods and Results A total of 330 patients without left ventricular systolic dysfunction (ejection fraction ≥50%) and significant epicardial coronary stenosis (fractional flow reserve >0.80) were analyzed. Cardiac diastolic dysfunction was defined by echocardiographic parameters (early diastolic transmitral flow velocity/early diastolic mitral annular velocity, e' velocity, tricuspid regurgitation velocity, and left atrial volume index). Overt CMD was defined as coronary flow reserve <2.0 and index of microcirculatory resistance ≥25 U. The primary end point was cardiovascular death or admission for heart failure during 5 years of follow-up. In patients without left ventricular systolic dysfunction and significant epicardial coronary stenosis, prevalence of cardiac diastolic dysfunction and overt CMD was 25.5% and 11.2%, respectively. Overt CMD was independently associated with cardiac diastolic dysfunction (adjusted odds ratio, 3.440 [95% CI, 1.599-7.401]; P=0.002). Patients with cardiac diastolic dysfunction showed significantly higher risk of the primary outcome than those without (adjusted hazard ratio [HR], 2.996 [95% CI, 1.888-4.755]; P<0.001). Patients with overt CMD also showed significantly higher risk of the primary outcome than those without (adjusted HR, 2.939 [95% CI, 1.642-5.261]; P<0.001). Presence of overt CMD was associated with significantly increased risk of cardiovascular death among the patients with cardiac diastolic dysfunction (43.8% versus 14.5%; P=0.006) but not in patients without cardiac diastolic dysfunction (interaction P<0.001). Inclusion of overt CMD into the model with cardiac diastolic dysfunction significantly improved predictive ability for cardiovascular death or heart failure admission (conconrdance index, 0.719 versus 0.737; P for comparison=0.034). Conclusions There was significant association between the presence of cardiac diastolic dysfunction and overt CMD. Both cardiac diastolic dysfunction and overt CMD were associated with increased risk of cardiovascular death or admission for heart failure. Integration of overt CMD into cardiac diastolic dysfunction showed improvement of the risk stratification in patients without significant left ventricular systolic dysfunction and epicardial coronary stenosis. Registration DIAST-CMD (Prognostic Impact of Cardiac Diastolic Function and Coronary Microvascular Function) registry; Unique identifier: NCT05058833.

Ivabradine Ameliorates Cardiac Diastolic Dysfunction in Diabetic Mice Independent of Heart Rate Reduction

Cardiac fibroblast (CF) proliferation and activation play important roles in cardiac fibrosis and diastolic dysfunction (DD), which are involved in fibrosis-associated cardiovascular diseases. A previous study showed that ivabradine, a specific heart rate (HR)-lowering agent, significantly ameliorated DD in diabetic db/db mice by reducing HR. Herein, we attempted to determine whether ivabradine has antifibrotic and cardioprotective effects in diabetic mice by directly suppressing CF proliferation and activation, independent of a reduction in HR. We found that knockdown of c-Jun N-terminal kinase (JNK) or p38 mitogen-activated protein kinase (MAPK), or treatment with ivabradine, reduced JNK and p38 MAPK phosphorylation and the protein expression of proliferating cell nuclear antigen, collagen I, collagen III, tissue inhibitor of matrix metalloproteinase 2, and α-smooth muscle actin, accompanied with upregulation of matrix metalloproteinase 2 both in high glucose-treated neonatal rat CFs and left ventricular CFs isolated from db/db mice. However, zatebradine (a HR-lowering agent) did not have these effects in vitro or in vivo. In addition, cardiac fibrosis and DD were ameliorated in db/db mice that were intravenously administered lentiviruses carrying short hairpin RNAs targeting JNK and p38 MAPK or administered ivabradine. Taken together, these findings demonstrate that the ivabradine-induced amelioration of cardiac fibrosis, and DD in db/db mice may be at least in part attributable to the suppression of CF proliferation and activation, through the inhibition of JNK and p38 MAPK.

Long-term outcomes and left ventricular diastolic function of sarcomere mutation-positive and mutation-negative patients with hypertrophic cardiomyopathy: a prospective cohort study

AIMS

Hypertrophic cardiomyopathy (HCM) is an inheritable disease that leads to sudden cardiac death and heart failure (HF). Sarcomere mutations (SMs) have been associated with HF. However, the differences in ventricular function between SM-positive and SM-negative HCM patients are poorly characterized.

METHODS AND RESULTS

Of the prospectively enrolled 374 unrelated HCM patients in Taiwan, 115 patients underwent both 91 cardiomyopathy-related gene screening and cardiovascular magnetic resonance (45.6 ± 10.6 years old, 76.5% were male). Forty pathogenic/likely pathogenic mutations were identified in 52 patients by next-generation sequencing. The SM-positive group were younger at first cardiovascular event (P = 0.04) and progression to diastolic HF (P = 0.02) with higher N-terminal pro-brain natriuretic peptide (NT-proBNP) [New York Heart Association (NYHA) Class III/IV symptoms with left ventricular ejection fraction > 55%] than the SM-negative group (P < 0.001). SM-positive patients had a greater extent of late gadolinium enhancement (P = 0.01), larger left atrial diameter (P = 0.03), higher normalized peak filling rate (PFR) and PFR ratio, and a greater reduction in global longitudinal strain than SM-negative patients (all P ≤ 0.01). During mean lifelong follow-up time (49.2 ± 15.6 years), SM-positive was a predictor of earlier HF (NYHA Class III/IV symptoms) after multivariate adjustment (hazard ratio 3.5; 95% confidence interval 1.3-9.7; P = 0.015).

CONCLUSION

SM-positive HCM patients had a higher extent of myocardial fibrosis and more severe ventricular diastolic dysfunction than those without, which may contribute to earlier onset of advanced HF, suggesting the importance of close surveillance and early treatment throughout life.

Combination of Plasma Biomarkers and Clinical Data for the Detection of Myocardial Fibrosis or Aggravation of Heart Failure Symptoms in Heart Failure with Preserved Ejection Fraction Patients

Background: Heart failure with preserved ejection fraction (HFpEF) is characterized by heart failure symptoms and structural change (including fibrosis). The relationship between novel biomarkers and the above components remains unclear. Methods: Seventy-seven HFpEF patients were recruited. All patients underwent echocardiography with tissue doppler imaging, cardiac magnetic resonance imaging (CMRI), and measurement of plasma inflammatory, remodelling, endothelial function, and heart failure biomarker levels. Myocardial fibrosis was defined by CMRI-extracellular volume. Forward conditional logistic regression was applied to demonstrate the determinants of myocardial fibrosis or heart failure symptoms. Results: The levels of growth differentiation factor, tissue inhibitor of metalloproteinase (TIMP)-1, galectin-3, and N-terminal pro b-type natriuretic peptide (NT-proBNP) were significantly higher in patients with more myocardial fibrosis. Matrix metalloproteinase-2 (MMP-2) and galectin-3 were independent markers of ECV. After adjusting for confounding factors, plasma galectin-3 and MMP-2 levels were correlated with myocardial fibrosis levels (odds ratio (OR): 1.05, 95% confidence interval (CI): 1.02 to 1.09, p = 0.005 and OR: 2.11, 95% CI: 1.35⁻3.28, respectively), while NT-proBNP level only was associated with heart failure symptoms. We developed a score system consisted of biomarkers and clinical parameters. The area under the curve of the scoring system receiver operating characteristic curve is 0.838 to predict the degree of myocardial diffuse fibrosis. Conclusions: In conclusion, we found that galectin-3 and MMP-2 were significantly associated with global cardiac fibrosis in HFpEF patients. We also combined plasma biomarkers and clinical data to identify HFpEF patients with more severe cardiac fibrosis.

CXL-1020, a Novel Nitroxyl (HNO) Prodrug, Is More Effective than Milrinone in Models of Diastolic Dysfunction-A Cardiovascular Therapeutic: An Efficacy and Safety Study in the Rat

The nitroxyl (HNO) prodrug, CXL-1020, induces vasorelaxation and improves cardiac function in canine models and patients with systolic heart failure (HF). HNO's unique mechanism of action may be applicable to a broader subset of cardiac patients. This study investigated the load-independent safety and efficacy of CXL-1020 in two rodent (rat) models of diastolic heart failure and explored potential drug interactions with common HF background therapies. In vivo left-ventricular hemodynamics/pressure-volume relationships assessed before/during a 30 min IV infusion of CXL-1020 demonstrated acute load-independent positive inotropic, lusitropic, and vasodilatory effects in normal rats. In rats with only diastolic dysfunction due to bilateral renal wrapping (RW) or pronounced diastolic and mild systolic dysfunction due to 4 weeks of chronic isoproterenol exposure (ISO), CXL-1020 attenuated the elevated LV filling pressures, improved the end diastolic pressure volume relationship, and accelerated relaxation. CXL-1020 facilitated Ca²⁺ re-uptake and enhanced myocyte relaxation in isolated cardiomyocytes from ISO rats. Compared to milrinone, CXL-1020 more effectively improved Ca²⁺ reuptake in ISO rats without concomitant chronotropy, and did not enhance Ca²⁺ entry via L-type Ca²⁺ channels nor increase myocardial arrhythmias/ectopic activity. Acute-therapy with CXL-1020 improved ventricular relaxation and Ca²⁺ cycling, in the setting of chronic induced diastolic dysfunction. CXL-1020's lusitropic effects were greater than those seen with the cAMP-dependent agent milrinone, and unlike milrinone it did not produce chronotropy or increased ectopy. HNO is a promising new potential therapy for both systolic and diastolic heart failure.