Improvement of Coronary Microvascular Function After Angiotensin Receptor Blocker Treatment With Irbesartan in Patients With Systemic Hypertension

Heart failure and microvascular dysfunction: an in-depth review of mechanisms, diagnostic strategies, and innovative therapies

Microvascular dysfunction (MVD) is increasingly recognized as a critical contributor to the pathogenesis of heart failure (HF), particularly in heart failure with preserved ejection fraction (HFpEF) and heart failure with reduced ejection fraction (HFrEF). Coronary microvascular dysfunction (CMD) significantly impacts HFpEF by reducing coronary flow reserve and myocardial perfusion reserve, leading to adverse outcomes such as myocardial ischemia, diastolic dysfunction, and increased risk of major cardiovascular events, including atrial fibrillation. In HFrEF, microvascular impairment is linked to heightened oxidative stress, reduced nitric oxide production, and activation of the renin-angiotensin-aldosterone system, further driving disease progression and contributing to poor prognosis. Advancements in diagnostic techniques, such as positron emission tomography, cardiac magnetic resonance imaging, and biomarker analysis, improve our ability to assess CMD in heart failure patients, enabling earlier diagnosis and risk stratification. Emerging therapies, including sodium-glucose cotransporter-2 inhibitors, angiotensin receptor-neprilysin inhibitors, and endothelial-targeted interventions, enhance microvascular function and improve patient outcomes. The role of personalized medicine is becoming increasingly important, as individualized therapeutic approaches tailored to patient-specific microvascular abnormalities are essential for optimizing treatment effectiveness. This review underscores the pivotal role of MVD in HF. It highlights the urgent need for innovative therapeutic strategies and diagnostic tools to address this complex condition and improve clinical outcomes for HF patients.

Ranolazine effectively improves clinical symptoms in patients with slow flow coronary arteries: a randomized, double-blind, placebo-controlled clinical trial

The coronary slow flow phenomenon (CSF) causes persistent chest pains that can affect patients' quality of life. We aimed to examine the ranolazine impacts on clinical symptoms in CSF patients. The present randomized, double-blind, placebo-controlled trial consisted of 44 patients with CSF. For two months, patients were randomized to receive ranolazine (500 mg/twice daily) or placebo plus optimal medications. EuroQol-visual analogic scale (VAS) and Seattle Angina Questionnaire (SAQ) were performed at baseline and after one and two months of treatment. At the beginning and after one month of treatment, no remarkable difference was assumed in the mean of EuroQol-VAS and all five SAQ parameters between the ranolazine and placebo groups. Additionally, the median of EuroQol-VAS (P < 0.001) and all five SAQ parameters, including physical limitation (P < 0.001), stability of angina (P < 0.001), frequency of angina (P < 0.001), treatment satisfaction (P = 0.003 and P < 0.001), and understanding of the disease (P < 0.001), has significantly propagated after two months of treatment in both ranolazine and placebo groups. Interestingly, following two months of treatment, the mean of EuroQol-VAS (P = 0.013), physical limitation (P = 0.041), stability of angina (P = 0.016), frequency of angina (P = 0.042), and treatment satisfaction (P = 0.037), in the ranolazine group has notably elevated comparatively to the placebo group. Our findings showed that ranolazine ameliorates clinical symptoms in CSF patients after two months of treatment. Therefore, ranolazine may be an appropriate candidate in CSF patients.

Coronary Microvascular Dysfunction: What Clinicians and Investigators Should Know

PURPOSE OF REVIEW

Abnormal structure and function of the coronary microvasculature have been implicated in the pathophysiology of multiple cardiovascular disease processes. This article reviews recent research progress related to coronary microvascular dysfunction (CMD) and salient clinical takeaways.

RECENT FINDINGS

CMD is prevalent in patients with signs and symptoms of ischemia and no obstructive epicardial coronary artery disease (INOCA), particularly in women. CMD is associated with adverse outcomes, including most frequently the development of heart failure with preserved ejection fraction. It is also associated with adverse outcomes in patient populations including hypertrophic cardiomyopathy, dilated cardiomyopathy, and acute coronary syndromes. In patients with INOCA, stratified medical therapy guided by invasive coronary function testing to define the subtype of CMD leads to improved symptoms. There are invasive and non-invasive methodologies to diagnose CMD that provide prognostic information and mechanistic information to direct treatment. Available treatments improve symptoms and myocardial blood flow; ongoing investigations aim to develop therapy to improve adverse outcomes related to CMD.

Relationship between malnutrition and coronary microvascular dysfunction in patients with nonischemic dilated cardiomyopathy

Background/ aim

Malnutrition is common in patients with nonischemic dilated cardiomyopathy (DCM), especially in the end stages of the disease where heart failure symptoms predominate. Malnutrition has been associated with atherosclerosis in patients with chronic kidney disease, but it is unknown whether a similar relationship exists between malnutrition and coronary microvascular dysfunction (CMD). In the present study, we aimed to analyse whether indices of malnutrition were associated with coronary flow reserve (CFR) in patients with DCM.

Materials and methods

A total of 33 cases who were prospectively followed up with by institutional DCM registry were found eligible for inclusion. Coronary flow reserve was measured with transthoracic echocardiography from the left anterior descending artery. The study sample was divided into 2 groups using a CFR cut-off value of 2.0. Geriatric nutritional index (GNI), prognostic nutritional index (PNI), and C-reactive protein/albumin ratio (CAR) were calculated.

Results

A total of 17 out of 33 cases (51.5%) had a low (<2.0) CFR. Both GNI and PNI were similar between the 2 groups, but the inflammatory–nutritional parameter CAR was significantly higher in those with a low CFR (1.18 ± 0.64 vs. 0.54 ± 0.28, P < 0.001). CA remained an independent predictor of CFR on multivariate regression (β = 0.65, P < 0.001) after adjustment for demographic (age, sex, body mass index), nutritional (GNI, PNI, albumin), and inflammatory (C-reactive protein) parameters. For a cut-off value of 0.80, CAR had a sensitivity of 85.7% and specificity of 73.6% to predict a CFR <2.0 (AUC: 0.835, 95%CI: 0.693–0.976, P = 0.001).

Conclusions

Our findings indicate that not malnutrition per se but a combination of inflammation activation and malnutrition is predictive of CMD in patients with DCM.

Effects of Oral Drugs on Coronary Microvascular Function in Patients Without Significant Stenosis of Epicardial Coronary Arteries: A Systematic Review and Meta-Analysis of Coronary Flow Reserve

Objective: This study aims to investigate the impact of cardiovascular medications on the coronary flow reserve (CFR) in patients without obstructive coronary artery disease (CAD).

Methods: We searched PubMed, EMBASE, and Cochrane databases from inception to 15 November 2019. Studies were included if they reported CFR from baseline to follow-up after oral drug therapy of patients without obstructive CAD. Data was pooled using random-effects modeling. The primary outcome was change in CFR from baseline to follow-up after oral drug therapy.

Results: A total of 46 studies including 845 subjects were included in this study. Relative to baseline, the CFR was improved by angiotensin-converting enzymes (ACEIs), aldosterone receptor antagonists (ARBs) [standard mean difference (SMD): 1.12; 95% CI: 0.77–1.47], and statins treatments (SMD: 0.61; 95%CI: 0.36–0.85). Six to 12 months of calcium channel blocker (CCB) treatments improved CFR (SMD: 1.04; 95% CI: 0.51–1.58). Beta-blocker (SMD: 0.24; 95% CI: −0.39–0.88) and ranolazine treatment (SMD: 0.31; 95% CI: −0.39–1.01) were not associated with improved CFR.

Conclusions: Therapy with ACEIs, ARBs, and statins was associated with improved CFR in patients with confirmed or suspicious CMD. CCBs also improved CFR among patients followed for 6–12 months. Beta-blocker and ranolazine had no impact on CFR.

Comprehensive treatment of microvascular angina in overweight women - a randomized controlled pilot trial

AIMS

Coronary microvascular dysfunction (CMD) carries a poor cardiovascular prognosis and may explain angina in women without obstructive coronary artery disease (CAD). Currently, no evidence-based treatment for CMD exists. We investigated whether reducing cardiovascular risk factors improves symptoms and microvascular function in women with non-endothelial dependent CMD and no obstructive CAD.

METHODS

We randomized 62 women aged 40-75, with body mass index (BMI) >25 kg/m2, angina ≥monthly, and coronary flow velocity reserve (CFVR) ≤2.5 to a 24-week intervention comprising low energy diet, exercise training, and optimized treatment of hypertension, dyslipidemia and diabetes or to control. Patients were assessed before randomization and after 24 weeks. Primary outcomes were CFVR assessed by transthoracic Doppler stress-echocardiography and angina burden by Seattle Angina Questionnaire (SAQ). Secondary outcomes were exercise capacity, body composition, glycemic control, myocardial function, and anxiety and depression symptoms.

RESULTS

Fifty-six participants (90%) completed the study. Median (IQR) age was 65.2 (57.1;70.7) years, BMI was 30.1 (28.4;32.7) kg/m2. The intervention resulted in relevant improvement in angina symptoms (9-21-point increase on SAQ-scales (all p<0.01)) but had no effect on CFVR (p = 0.468). Mean (CI) weight loss was 9.6 (7.80;11.48) kg, (p<0.0001). There was a significant mean (CI) decrease in depression symptoms = 1.16 (0.22;2.12), triglycerides = 0.52 (0.25;0.78) mmol/L, total cholesterol = 0.55 (0.12;0.98) mmol/L, and HbA1c in diabetics = 27.1 (1.60;52.6) mmol/mol but no effect on other secondary outcomes.

CONCLUSION

A major weight loss and intensified risk factor control resulted in significantly improved angina burden but no improvement of coronary microvascular function among women with microvascular angina.

Coronary microvascular dysfunction

Patients with coronary microvascular dysfunction (CMVD) represent a widespread population and despite the good prognosis, many of them have a poor quality of life with strong limitations in their daily activities because of the angina symptoms. This article summarizes the most frequent clinical presentation pictures like stable and unstable microvascular angina. Main risk factors are discussed, followed by the latest updates on the subject about different pathogenic hypotheses, diagnosis and treatment. Not very well understood microvascular alterations, like slow flow phenomenon and no reflow are discussed and both prognosis and the impact of the disease in the quality of life are analyzed.

Treatment strategies in coronary microvascular dysfunction: A systematic review of interventional studies

CMD has been associated with a wide spectrum of diseases and conditions, and it has proven to be a strong prognostic marker of morbidity and mortality. Despite increased attention, guideline-based treatment recommendations are lacking. We performed a systematic review of pharmacological and nonpharmacological interventions to improve coronary perfusion, assessed by IC Doppler, TTDE, PET, CMRI, transthoracic contrast perfusion echocardiography, and dilution techniques. No restrictions were made regarding the study design (randomized, placebo-controlled/randomized with active comparators/nonrandomized with or without a control group), the cardiac condition studied, or the coronary microvascular function at baseline. An electronic database search yielded 4485 records of which 80 studies met our inclusion criteria. Included studies were sorted according to intervention and study design. Studies were small and heterogeneous in methodology, and only few were placebo-controlled. Although some treatments looked promising, we found that no specific treatment was sufficiently well documented to be recommended in any patient groups. There is a need for larger well-designed clinical trials, and we suggest that future studies stratify study populations according to pathogenic mechanisms, thereby investigating whether an individualized treatment approach would be more successful.

Correlation between carotid intima-media roughness and cardiovascular risk factors

Arterial intima-media roughness (IMR) may indicate an early manifestation of atherosclerosis. To date, few studies have been performed to quantitatively evaluate carotid IMR by ultrasonography (US). The aim of the present study was to analyze the effect of cardiovascular risk factors on carotid IMR. A total of 185 subjects were enrolled for US examination of carotid arteries. Carotid intima-media thickness (IMT) and IMR were measured in US images by a novel automatic software. According to the number of combined high-risk factors for coronary heart disease, subjects were assigned to four groups (risk groups 0, 1, 2 and 3+). IMR was lowest in risk group 0 (32.9±2.7 µm), higher in risk group 1 (64.5±6.9 µm; P<0.01 vs. risk group 0) and highest in risk groups 2 and 3+ (89.1±7.4 and 92.0±6.7 µm, respectively; P<0.01 vs. risk groups 0 and 1). According to a multivariate regression analysis, age, systolic blood pressure, smoking status and the triglyceride/high-density lipoprotein cholesterol ratio were significant predictors of IMR. There was a progressive increase in carotid artery plaque with increasing tertiles of IMR (4.9, 33.9 and 53.2% in tertiles 1, 2 and 3, respectively; P<0.05). Compared with that of subjects in the lowest tertile of IMR, those in the highest tertile had a significantly elevated risk of the presence of plaque in the carotid tree (odds ratio=10.61, 95%CI: 2.15–52.49, P=0.004). Quantification of carotid IMR from US images with this software is feasible, and carotid IMR, which may help estimate the extent of atherosclerosis, may be used as a complementary factor to stratify patients with cardiovascular risk factors.

Potential Protective Role of Blood Pressure-Lowering Drugs on the Balance between Hemostasis and Fibrinolysis in Hypertensive Patients at Rest and During Exercise

In patients with hypertension, the triad represented by endothelial dysfunction, platelet hyperactivity, and altered fibrinolytic function disturbs the equilibrium between hemostasis and fibrinolysis and translates into a hypercoagulable state, which underlies the risk of thrombotic complications. This article reviews the scientific evidence regarding some biological effects of antihypertensive drugs, which can protect patients from the adverse consequences of hypertensive disease, improving endothelial function, enhancing antioxidant activity, and restoring equilibrium between hemostatic and fibrinolytic factors. These protective effects appear not to be mediated through blood pressure reduction and are not shared by all molecules of the same pharmacological class.

Effect of renal denervation on coronary flow reserve in patients with resistant hypertension

Renal denervation (RDN) is a potential modality in the treatment of patients with resistant hypertension (RH) and has shown beneficial effect on a variety of cardiovascular surrogate markers. Coronary flow reserve, as assessed by transthoracic Doppler echocardiography (TDE-CFR) is impaired in patients with hypertension and is an independent predictor of cardiac morbidity. However, data on the effect of RDN on TDE-CFR are scarce. The main objective of this study was to assess the effect of RDN on TDE-CFR. Twenty-six consecutive patients with RH (9 female and 17 male; mean age 62 ± 8 years; mean number of antihypertensive drugs 4·2 ± 1·6) underwent bilateral RDN. CFR was assessed at baseline and 6 months after intervention. Mean flow velocity was measured in the left anterior descending artery by transthoracic Doppler echocardiography at baseline and during adenosine infusion (TDE-CFR). Systolic office blood pressure was reduced at follow-up (174 ± 24 versus 162 ± 27 mmHG; P = 0·01). Mean systolic ambulatory blood pressure decreased from 151 ± 21 to 147 ± 18 (P = 0·17). TDE-CFR remained unchanged 6 months after intervention (2·7 ± 0·6 versus 2·7 ± 0·7; P = 0·67). In conclusion, renal denervation was not associated with any changes in regard to coronary flow reserve at 6-month follow-up.

Coronary flow reserve in patients with resistant hypertension

Resistant hypertension is associated with increased risk for cardiovascular events. Coronary flow reserve (CFR) is impaired in patients with hypertension and an independent predictor of cardiac mortality. However, there are no published data on CFR in the subset of treatment-resistant hypertension. The aim of this study was to assess CFR in patients with resistant hypertension. Twenty-five consecutive patients with primary resistant hypertension, scheduled for renal denervation, 25 matched patients with controlled hypertension, and 25 healthy controls underwent transthoracic colour Doppler echocardiography at rest and during adenosine infusion. Patients with hypertension were pair-matched with regard to age, sex, ischemic heart disease, diabetes mellitus, smoking status, and body-mass index. Healthy controls were selected according to age and sex. Mean flow velocity was measured in the left coronary anterior descending artery. Baseline mean flow velocities were similar in patients with controlled and resistant hypertension. CFR was significantly lower in patients with resistant hypertension as compared to individuals with non-resistant hypertension (2.7 ± 0.6 vs. 3.1 ± 0.8; p = 0.03). Systolic office blood pressure was significantly higher in patients with resistant hypertension (169 ± 20 vs. 144 ± 21 mm Hg; p < 0.01). Heart rate, ventricular mass, and ejection fraction were similar in the two groups. Healthy controls showed significantly lower baseline velocity, higher CFR, and lower blood pressure as compared to hypertensives. Resistant hypertension was associated with impaired CFR as compared to individuals with non-resistant hypertension indicating impaired cardiac microvascular function which may contribute to the increased risk of adverse outcome in patients with resistant hypertension.

Pleiotropic effects of the acute and chronic inhibition of the renin-angiotensin system in hypertensives

Renin-angiotensin system (RAS) inhibition may exert beneficiary pleiotropic effects on heart hemodynamics in hypertensive patients. We aimed to assess these effects on coronary flow reserve (CFR) and left ventricular (LV) filling pressure after acute and long-term treatment. Thirty-nine patients (48.4±6.8 years) with newly diagnosed, never-treated essential arterial hypertension were consecutively recruited from an outpatient hypertension clinic. CFR in the left anterior descending artery and the ratio of mitral inflow E wave to the averaged mitral annulus tissue velocity of the E waves (E/e' ratio), as an estimate of LV filling pressure, were assessed by Doppler echocardiography. In the acute phase of the study, consecutive eligible patients were assigned to receive po Quinapril (Q) 20 mg (n=15) or Losartan (L) 100 mg (n=14) or no treatment (n=10) and were reexamined 2 h post treatment. In the chronic phase of the study, the patients were reevaluated after 1 month on the assigned treatment. During the acute phase, CFR (P=0.005) was significantly improved in the RAS inhibition as compared with the control group, independently of blood pressure (BP) changes. The E/e' ratio was also marginally improved (P=0.053), but this effect was more pronounced in patients with E/e' ratio>8 (P=0.005). CFR and E/e' ratio were also improved after 1 month of treatment, particularly in responders after the acute phase. In hypertensive patients, RAS inhibition acutely improved CFR and E/e' ratio independently of BP changes. An acute positive response in these parameters was closely related to sustained improvement after 1 month of single-drug treatment.