Coronary flow slows as renal function worsens

Renal Dysfunction Increases Risk of Adverse Cardiovascular Events in 5-Year Follow-Up Study of Intermediate Coronary Artery Lesions

BACKGROUND Progression of chronic coronary syndrome (CCS) is influenced by chronic kidney disease (CKD). This 5-year follow-up study aimed to assess 100 patients with 118 intermediate coronary artery lesions evaluated by fractional flow reserve (FFR) and intravascular imaging stratified according to renal function. MATERIAL AND METHODS This prospective study enrolled patients with intermediate coronary stenosis identified by coronary angiogram. Patients with severe renal dysfunction (estimated glomerular filtration rate (eGFR) <45 ml/min/1.73 m²) were excluded from the study. The remaining were divided into 2 groups according to eGFR: 45-60 ml/min/1.73 m² for mild-to-moderate renal dysfunction and >60 ml/min/1.73 m² for no renal dysfunction. We analyzed intermediate-grade stenoses (40-80% as assessed in coronary angiography) with the use of optical coherence tomography (OCT), FFR, and intravascular ultrasound (IVUS). RESULTS Renal dysfunction patients were older (67.7±8.1 vs 63.6±9.7 years, P=0.044). Lesion characteristics, including plaque type and minimal lumen area in OCT, showed no significant differences between the renal dysfunction and no renal dysfunction groups. Thin-cap fibroatheroma, calcific plaques, lipidic plaques, and fibrous plaques had similar prevalence. FFR values and IVUS parameters did not significantly differ between the groups. Over a 5-year follow-up, individuals with mild-to-moderate renal dysfunction had an elevated risk of all-cause mortality and major adverse cardiovascular events in multivariate analyses adjusted for age and sex. CONCLUSIONS Mild-to-moderate renal dysfunction was not associated with significant differences in OCT- and IVUS-derived plaque morphology nor with functional indices characterizing intermediate-grade coronary stenoses. Renal dysfunction was related to a higher risk of all-cause mortality and major adverse cardiovascular events prevalence in 5-year follow-up.

Small vessel disease: Connections between the kidney and the heart

Small vessel disease is characterized by global dysfunction of the microvascular system leading to reduced perfusion of various organ systems. The kidney is significantly vulnerable for microvascular dysfunction given its intricate capillary network and extensive endocrine influence. Studies have demonstrated a relationship between impaired renal function and small vessel disease in other organ systems, particularly the heart. Here we discuss the relationship between the kidney and the heart in the setting of microvascular dysfunction and identify areas of future study to better understand this relationship and potentially identify novel therapeutic strategies.

Microvascular Dysfunction as a Systemic Disease: A Review of the Evidence

Microvascular dysfunction describes a varied set of conditions that includes vessel destruction, abnormal vasoreactivity, in situ thrombosis, and fibrosis, which ultimately results in tissue damage and progressive organ failure. Microvascular dysfunction has a wide array of clinical presentations, ranging from ischemic heart disease to renal failure, stroke, blindness, pulmonary arterial hypertension, and dementia. An intriguing unifying hypothesis suggests that microvascular dysfunction of specific organs is an expression of a systemic illness that worsens with age and is accelerated by vascular risk factors. Studying relationships across a spectrum of microvascular diseases affecting the brain, retina, kidney, lung, and heart may uncover shared pathologic mechanisms that could inform novel treatment strategies. We review the evidence that supports the notion that microvascular dysfunction represents a global pathologic process. Our focus is on studies reporting concomitant microvascular dysfunction of the heart with that of the brain, kidney, retina, and lung.

Quantitative flow ratio and fractional flow reserve mismatch - clinical and biochemical predictors of measurement discrepancy

INTRODUCTION

Fractional flow reserve (FFR) is the gold standard for functional assessment of intermediate lesions. However, assessing a stenosis with pressure wire prolongs the procedure, increases costs and carries a risk of procedure-related adverse events. Quantitative flow ratio (QFR) is a wire-free method for detection of significant ischemia based on 3D reconstruction of angiographic images and TIMI frame count.

AIM

To evaluate the influence of laboratory and clinical variables on QFR-FFR mismatch.

MATERIAL AND METHODS

We retrospectively computed QFR (Medis Suite XA/QAngio XA 3D/QFR, Medis/Netherlands) in suitable cases with corresponding FFR (PressureWire, Abbott, US). Uni-/multivariate analysis was performed to identify clinical and biochemical predictors of QFR-FFR mismatch.

RESULTS

Two hundred six lesions (196 patients, 76% male, mean age: 66.4 ±10.1 years) were included. Chronic kidney disease (CKD) and insulin-treated diabetes mellitus (ITDM) were associated with significantly larger differences between QFR and FFR values (-0.062 ±0.031 vs. -0.025 ±0.068; p = 0.027 and -0.059 ±0.07 vs. -0.027 ±0.074; p = 0.039; respectively). CKD was associated with a decrease of diagnostic efficiency (AUC = 0.67, 95% CI: 0.46-0.88 vs. AUC = 0.89, 95% CI: 0.84-0.94, p = 0.05). For biochemical variables only weak Spearman correlations were identified for hemoglobin concentration (r = -0.18) and hematocrit levels (r = -0.18).

CONCLUSIONS

CKD may impair the QFR diagnostic accuracy. Larger, prospective studies are needed to further explore this potential relationship.

Factors associated with the no-reflow phenomenon following percutaneous intervention of saphenous vein coronary bypass grafts

BACKGROUND

We investigated clinical and procedural factors associated with the no-reflow phenomenon following percutaneous coronary intervention (PCI) of the saphenous-vein grafts (SVG).

METHODS

A cross-sectional study was done on patients who had undergone PCI of the SVG. Patients' medical documents were reviewed for demographic, clinical, laboratory, and procedural data. Slow/no-reflow was defined based on the thrombolysis in myocardial infarction (TIMI) grade (0 to 2). Univariate and multiple logistic regression analyses were performed to investigate factors associated with slow/no-reflow and P < 0.050 was considered as significant.

RESULTS

A total of 205 patients were studied (81% man, mean ± standard deviation of age was 66.8 ± 9.6 years). Slow/no-reflow was found in 38 (18.5%) patients. High diastolic blood pressure (P = 0.010), leukocytosis (P = 0.017), diffuse lesions (P = 0.007), degenerated SVG (P < 0.001), proximal lesions (P < 0.001), thrombosis (P = 0.013), and lower number of used stents during procedure (P = 0.032) were associated with slow/no-reflow in unadjusted analyses. Factors independently associated with slow/no-reflow were pre-procedural high diastolic blood pressure with odds ratio (OR) = 3.858 [95% confidence interval (95% CI), 1.157-12.860], degenerated SVG with OR = 5.901 (95% CI: 1.883-18.492), proximal lesions with OR = 5.070 (95% CI: 1.822-14.113), pre-intervention TIMI grade with OR = 0.618 (95% CI: 0.405-0.942), number of used stents for PCI with OR = 0.074 (95% CI: 0.011-0.481) for > 1 stent, and length of stents used for PCI with OR = 0.100 (95% CI: 0.019-0.529) for > 30 mm stents.

CONCLUSION

This study on the clinical and procedural factors associated with the slow/no-reflow phenomenon following PCI of the SVG can be used in risk estimation of this serious complication and tailoring preventive strategies to at-risk patients.

Fractional Flow Reserve Evaluation and Chronic Kidney Disease: Analysis From a Multicenter Italian Registry (the FREAK Study)

OBJECTIVES

To establish if the presence of chronic kidney disease (CKD) influences fractional flow reserve (FFR) value in patients with intermediate coronary stenosis.

BACKGROUND

FFR-guided coronary revascularization reduces cardiac adverse events in patients with coronary artery disease. CKD impairs microcirculation and increases cardiovascular risk. Whether CKD presence may limit FFR accuracy is unknown.

METHODS

We used data from a multicenter prospective registry enrolling 1.004 patients undergoing FFR evaluation for intermediate stenosis. We assessed the relationship between clinical and angiographic variables and FFR measurement. CKD was defined as CrCl value ≤45 ml/min. FFR value was considered potentially flow-limiting, and therefore positive, if ≤0.80. The index of microcirculatory resistance (IMR) was calculated in 20 patients stratified according CrCl value (single-center substudy).

RESULTS

FFR measurement was positive in 395 (39%) patients. Overall, 131 (13%) patients had CKD. Patients with CrCl ≤45 ml/min showed significantly higher FFR values as compared to the others (0.84 ± 0.07 vs. 0.81 ± 0.08, p < 0.001). Positive FFR occurrence was lower in patients with CrCl ≤45 ml/min (27% vs. 41%, p < 0.01). After multivariable analysis, diabetes (HR 1.07, 95%CI 1.008-1.13, p = 0.03), left anterior descending (HR 1.35, 95%CI 1.27-1.43, p < 0.001) and CrCl ≤45 ml/min (HR 0.92, 95%CI 0.87-0.97, p = 0.005) emerged as independent predictors of FFR measurement. Accordingly, IMR values were higher in patients with CrCl ≤45 ml/min (32 U [28245] vs. 16 U [11220], p < 0.01).

CONCLUSIONS

FFR and IMR measurements differ between CKD patients and those with normal renal function. Flow-limiting FFR is less frequent in patients with CrCl ≤45 ml/min. © 2015 Wiley Periodicals, Inc.

Association of glomerular filtration rate with slow coronary flow in patients with normal to mildly impaired renal function

We evaluated the association between estimated glomerular filtration rate (eGFR) and slow coronary flow (SCF) in patients with normal to mildly impaired renal function; 211 patients with angiographically proven SCF and 219 controls were studied. Patients were categorized based on the angiographic findings as with or without SCF. We used the Modification of Diet in Renal Disease equation to calculate eGFR. The frequency of mildly decreased eGFR, serum uric acid levels, and eGFR was higher in the SCF group. Patients with mildly impaired renal function had higher thrombolysis in myocardial infarction frame counts in 3 major coronary arteries. In logistic regression analysis, uric acid (odds ratio [OR] = 1.323, 95% confidence interval [CI] = 1.109-1.572, P = .002) and eGFR (OR = 0.972, 95% CI = 0.957-0.987, P < .001) were independent correlates of SCF. In conclusion, eGFR was significantly correlated with SCF in patients with normal to mildly impaired renal function.

Echocardiographic epicardial adipose tissue predicts subclinical atherosclerosis: epicardial adipose tissue and atherosclerosis

We examined the relationship between coronary flow rate and epicardial adipose tissue (EAT) in patients with slow coronary flow (SCF) and normal coronary arteries. The study included 40 consecutive patients with stable angina pectoris who had normal coronary arteries. All patients underwent echocardiography. To determine the SCF, thrombolysis in myocardial infarction (TIMI) frame count method was used. Half of the patients had SCF at least in 1 coronary artery. Thrombolysis in myocardial infarction frame counts, the mean TIMI frame count, and EAT thickness were significantly higher in patients with SCF. Slow coronary flow showed a significantly positive correlation with EAT thickness. Epicardial adipose tissue thickness was the only independent predictor of SCF. Our findings suggest that there is a significant correlation between the SCF and EAT. Therefore, echocardiographic EAT may become a predictor of subclinical atherosclerosis in patients with stable angina pectoris.