Application of pressure-derived myocardial fractional flow reserve in chronic hemodialysis patients

Relation Between Calcium-Phosphorus Product and Total Coronary Artery Occlusion in a Nonchronic Kidney Disease Population: A Cross-Sectional Study

Excessive calcium-phosphorus product (Ca-P product) in patients with chronic kidney disease (CKD) is associated with coronary artery calcification and coronary artery disease, but the relation between Ca-P product and coronary artery disease in non-CKD populations has rarely been reported. Therefore, we designed a cross-sectional study to investigate the role of Ca-P product in total coronary artery occlusion (TCAO) in a non-CKD population. We reviewed 983 patients who underwent coronary angiography at Guangyuan Central Hospital from February 2018 to January 2020. Ca-P product (mg2/dl2) was calculated as Ca (mmol/L) × 4 × P (mmol/L) × 3.1 and was analyzed as a continuous and tertiary variable. TCAO was defined as complete occlusion of any coronary artery by coronary angiography (thrombolysis in myocardial infarction flow grade 0). Statistical analysis was performed using univariate and multivariate logistic regression models and restricted cubic splines. Univariate logistic regression analysis showed a statistically significant association between Ca-P product and TCAO (odds ratio [OR] 0.97, 95% confidence interval [CI] 0.95 to 0.99, p <0.001). After stepwise adjustment for covariates, the risk of TCAO was reduced by 40% in the high versus low Ca-P group (OR 0.6, 95% CI 0.38 to 0.95, p = 0.031), and the risk of TCAO was predicted to decrease by 4% (OR 0.96, 95% CI 0.94 to 0.99, p = 0.006) for each unit increase in Ca-P product. Restricted cubic splines showed a nonlinear relation between Ca-P product and TCAO, with a significant decrease in the risk of TCAO after reaching 27.46 (nonlinear p = 0.047). In conclusion, in non-CKD populations, a higher Ca-P product (≥27.46 mg2/dl2) may help avoid TCAO.

Prognostic Values of Fractional Flow Reserve Based on Clinical Outcomes in Patients on Chronic Hemodialysis

The fractional flow reserve (FFR) cut-off values of 0.75 or 0.8 have been widely used; however, whether they apply to patients on hemodialysis remains unknown. We aimed to investigate the cut-off value of FFR associated with clinical outcomes in patients on hemodialysis. Using the Japanese multicenter registry, we analyzed data of patients on hemodialysis with measured FFR between January 2010 and December 2016. Survival classification and regression tree analysis for the composite primary outcome of cardiovascular mortality, myocardial infarction, and target vessel revascularization revealed a threshold FFR of 0.83. Multivariate Cox regression analyses were performed for the clinical outcomes. Additionally, the primary outcome was analyzed using propensity score matching by dividing the patients into complete and incomplete revascularization groups according to the presence of residual lesions with an FFR of ≤0.83 after the intervention. Of the 212 included patients, 112 (52.8%) had lesions with an FFR of ≤0.83. After adjusting for confounders, an FFR of ≤0.83 was associated with a higher risk for the primary outcome (adjusted hazard ratio 2.01, 95% confidence interval 1.11 to 3.66, p = 0.021). Propensity score matching showed that complete revascularization for lesions with an FFR of ≤0.83 was associated with a reduced risk for the primary outcome compared with incomplete revascularization (hazard ratio 0.38, 95% confidence interval 0.20 to 0.71, log-rank p = 0.0016). In conclusion, an FFR of ≤0.83 was an independent predictor of clinical events in patients on hemodialysis. Furthermore, complete revascularization was associated with better clinical outcomes. Thus, this population may require a distinct FFR cut-off value.

Cardiovascular events in patients with deferred lesions and chronic kidney disease

No study has reported the association between the worsening of chronic kidney disease (CKD) and cardiovascular events in patients with deferred coronary artery lesions. We included patients with deferred lesions, defined as a fractional flow reserve (FFR) value > 0.80 treated with conservative medical therapy. Patients were divided into three groups: group 1, CKD stages 1-2; group 2, CKD stages 3-5; and group 3, CKD stage 5D (hemodialysis), with the clinical outcomes compared. The primary endpoint was the first occurrence of target vessel myocardial infarction, ischemia-driven target-vessel revascularization, or all-cause death. The primary endpoint was noted in 17, 25, and 36 patients in groups 1, 2, and 3, respectively. Within the three groups, the incidence rate of deferred lesions was 7.0%, 10.4%, and 32.4%, respectively. No difference was observed in the incidence of the primary endpoint between groups 1 and 2 (log-rank p = 0.16). However, the patients in group 3 had a significantly higher risk for the primary endpoint than those in groups 1 and 2 (log-rank p < 0.0001). In the multivariate Cox proportional hazards model, the patients in group 3 exhibited a higher incidence of the primary endpoint than those in group 1 (HR: 2.14; 95% CI 1.02-4.49; p < 0.01). Careful management is needed in patients undergoing hemodialysis, even if coronary artery stenosis is considered a deferred lesion.

Pathophysiological concepts and screening of cardiovascular disease in dialysis patients

Dialysis patients experience 10-20 times higher cardiovascular mortality than the general population. The high burden of both conventional and nontraditional risk factors attributable to loss of renal function can explain higher rates of cardiovascular disease (CVD) morbidity and death among dialysis patients. As renal function declines, uremic toxins accumulate in the blood and disrupt cell function, causing cardiovascular damage. Hemodialysis patients have many cardiovascular complications, including sudden cardiac death. Peritoneal dialysis puts dialysis patients with end-stage renal disease at increased risk of CVD complications and emergency hospitalization. The current standard of care in this population is based on observational data, which has a high potential for bias due to the paucity of dedicated randomized clinical trials. Furthermore, guidelines lack specific guidelines for these patients, often inferring them from non-dialysis patient trials. A crucial step in the prevention and treatment of CVD would be to gain better knowledge of the influence of these predisposing risk factors. This review highlights the current evidence regarding the influence of advanced chronic disease on the cardiovascular system in patients undergoing renal dialysis.

Fractional Flow Reserve Versus Instantaneous Wave-Free Ratio in Assessment of Lesion Hemodynamic Significance and Explanation of their Discrepancies. International, Multicenter and Prospective Trial: The FiGARO Study

Background

The FiGARO (FFR versus iFR in Assessment of Hemodynamic Lesion Significance, and an Explanation of Their Discrepancies) trial is a prospective registry searching for predictors of fractional flow reserve/instantaneous wave‐free ratio (FFR/iFR) discrepancy.

Methods and Results

FFR/iFR were analyzed using a Verrata wire, and coronary flow reserve was analyzed using a Combomap machine (both Philips‐Volcano). The risk polymorphisms for endothelial nitric oxide synthase and for heme oxygenase‐1 were analyzed. In total, 1884 FFR/iFR measurements from 1564 patients were included. The FFR/iFR discrepancy occurred in 393 measurements (20.9%): FFRp (positive)/iFRn (negative) type (264 lesions, 14.0%) and FFRn/iFRp (129 lesions, 6.8%) type. Coronary flow reserve was measured in 343 lesions, correlating better with iFR (R=0.56, P<0.0001) than FFR (R=0.36, P<0.0001). The coronary flow reserve value in FFRp/iFRn lesions (2.24±0.7) was significantly higher compared with both FFRp/iFRp (1.39±0.36), and FFRn/iFRn lesions (1.8±0.64, P<0.0001). Multivariable logistic regression analysis confirmed (1) sex, age, and lesion location in the right coronary artery as predictors for FFRp/iFRn discrepancy; and (2) hemoglobin level, smoking, and renal insufficiency as predictors for FFRn/iFRp discrepancy. The FFRn/iFRp type of discrepancy was significantly more frequent in patients with both risk types of polymorphisms (endothelial nitric oxide synthase_r+heme oxygenase‐1_r): 8 patients (24.2%) compared with FFRp/iFRn type of discrepancy: 2 patients (5.9%), P=0.03.

Conclusions

Predictors for FFRp/iFRn discrepancy were sex, age, and location in the right coronary artery. Predictors for FFRn/iFRp were hemoglobin level, smoking, and renal insufficiency. The risk type of polymorphism in endothelial nitric oxide synthase and heme oxygenase‐1 genes was more frequently found in patients with FFRn/iFRp type of discrepancy.

Registration

URL: https://clinicaltrials.gov; Unique identifier: NCT03033810.

Five-Year Outcomes After Fractional Flow Reserve-Based Deferral of Revascularization in Chronic Coronary Syndrome: Final Results From the J-CONFIRM Registry

BACKGROUND

Little large-scale data is available about the long-term (beyond 3 years) clinical outcomes after fractional flow reserve (FFR)-based deferral of revascularization in clinical practice. We sought to assess the 5-year outcomes after deferral of revascularization based on FFR.

METHODS

The J-CONFIRM registry (Long-Term Outcomes of Japanese Patients With Deferral of Coronary Intervention Based on Fractional Flow Reserve in Multicenter Registry) prospectively enrolled 1263 patients with 1447 lesions in whom revascularization was deferred based on FFR from 28 Japanese centers. The primary study end point was the cumulative 5-year incidence of target vessel failure (TVF), including cardiac death, target vessel-related myocardial infarction, and clinically driven target vessel revascularization.

RESULTS

Five-year follow-up was completed in 92.2% of patients. The 5-year TVF rate was 11.6% in deferred lesions, mainly driven by clinically driven target vessel revascularization (9.8%). Cardiac death and target vessel-related myocardial infarction were 1.9% and 0.95%, respectively. Cumulative 5-year incidence of TVF was similar between the FFR 0.75 to 0.80 and 0.81 to 0.85 groups even after adjustment for baseline characteristics (12.2% versus 13.0%, inverse probability-weighted hazard ratio, 0.86 [95% CI, 0.46-1.60]; P=0.63). Compared with the almost normal FFR (0.86-1.00) group, the significant (<0.75) and borderline (0.75-0.85) FFR groups showed a higher incidence of TVF at 5 years (29.9% versus 12.8% versus 8.6%, P<0.001). Independent predictors of the 5-year TVF were hemodialysis, FFR value, left main coronary artery lesion, prior percutaneous coronary intervention, and male sex.

CONCLUSIONS

The 5-year TVF rate was 11.6% in deferred lesions, mainly driven by clinically driven target vessel revascularization. Notably, cardiac death and target vessel-related myocardial infarction rarely occurred during the follow-up. Our findings highlight the long-term safety of FFR-based deferral of revascularization in patients with chronic coronary syndrome. Registration: URL: https://www.umin.ac.jp/ctr; Unique identifier: UMIN000014473.

Chronic elevation of cardiac troponin I predicts the extent of coronary disease in hemodialysis patients presenting with acute enzyme elevation

Introduction

Elevation of cardiac troponin I (cTn-I) is associated with coronary artery disease (CAD) in asymptomatic patients with end-stage renal disease (ESRD) receiving hemodialysis. We aim to investigate the diagnostic value of chronically elevated cTn-I in ESRD patients presenting with an acute rise in serum cTn-I levels.

Methods

We performed a retrospective analysis of 364 patients. Using coronary angiography, we correlated baseline elevation of cTn-I with the severity of CAD when hemodialysis patients present with acute symptomatic elevation in serum cTn-I.

Results

In hemodialysis patients presenting with a rise in serum cTn-I above baseline levels, 59% had severe CAD, and 17% had no angiographic evidence of CAD. Hemodialysis patients with severe CAD had significantly higher baseline cTn-I levels compared to patients with non-severe CAD or normal coronaries (p < 0.0001). Baseline elevation of cTn-I in the severe CAD group was correlated with the degree of CAD occlusion (r2 0.56, p < 0.0001), fitting a positive linear model. Furthermore, baseline cTn-I differentiates between patients with and without severe CAD with a test accuracy of 0.72 (95% CI, 0.69-0.75, p < 0.001). At a value of ≥0.2 ng/mL (cutoff for myocardial necrosis), the specificity of baseline cTn-I for underlying severe CAD was 0.95.

Conclusions

Elevated baseline cTn-I has good accuracy for anticipating more advanced angiographic CAD when hemodialysis patients present with a symptomatic rise in serum cTn-I above baseline levels. Baseline elevation of cTn-I can be used for cardiac disease risk management in hemodialysis patients presenting with symptoms suggestive of CAD.

High dose escalation of intracoronary adenosine in the assessment of fractional flow reserve: A retrospective cohort study

Maximal hyperaemia for fractional flow reserve (FFR) may not be achieved with the current recommended doses of intracoronary adenosine. Higher doses (up to 720 μg) have been reported to optimize hyperaemic stimuli in small dose-response studies. Real-world data from a large cohort of patients is needed to evaluate FFR results and the safety of high-dose escalation. This is a retrospective study aimed to evaluate the safety and frequency of FFR ≤0.8 after high-dose escalation of intracoronary adenosine. Data were extracted from the medical databases of two university hospitals. Increasing doses (100, 200, 400, 600, and 800 μg) of adenosine were administered as intracoronary boluses until FFR ≤0.8 was achieved or heart block developed. The percentage of FFR ≤0.8 after higher-dose escalation was compared with those at conventional doses, and the predictors for FFR ≤0.8 after higher doses were analysed. In the 1163 vessels of 878 patients, 402 vessels (34.6%) achieved FFR ≤0.8 at conventional doses and 623 vessels (53.6%) received high-dose escalation. An additional 84 vessels (13.5%) achieved FFR ≤0.8 after high-dose escalation. No major complications developed during high-dose escalation. Borderline FFR (0.81-0.85) at the conventional dose, stenosis >60%, and triple-vessel disease increased the likelihood of FFR ≤0.8 after high-dose escalation, but chronic kidney disease decreased it. For vessels of borderline FFR at conventional doses, 46% achieved FFR ≤0.8 after high-dose escalation. In conclusion, High-dose escalation of intracoronary adenosine increases the frequency of FFR ≤0.8 without major complications. It could be especially feasible for borderline FFR values near the 0.8 diagnostic threshold.

Impact of hydrostatic pressure on fractional flow reserve: in vivo experimental study of anatomical height difference of coronary arteries

BACKGROUND

Although pressure equalization of the sensor-tipped guidewire and systemic pressure is mandatory in measuring fractional flow reserve (FFR), pressure in the distal artery (Pd) with wire advancement can be influenced by hydrostatic pressure related to the height difference between the catheter tip and the distal pressure sensor. We therefore analyzed the impact of hydrostatic pressure on FFR in vivo by modification of the height difference.

METHODS

To reveal the anatomical height difference in human coronary arteries, measurement was performed during computed tomography angiography (CTA) of five consecutive patients. Utilizing the healthy coronary arteries of female swine, height difference diversity was reproduced by body rotation and vertical inclination. FFR measurements were performed during maximum hyperemia with adenosine. The height difference was calculated fluoroscopically with a contrast medium-filled balloon for reference.

RESULTS

In human coronary CTA, height averages from the ostium in the left anterior descending artery (34.6 mm) were significantly higher than in the left circumflex (-15.5 mm, p = 0.008) and right coronary arteries (-2.3 mm, p = 0.008). In our swine model, reproduced height variation ranged from -7.2 cm to +6.5 cm. Mean FFR was significantly lower in positive sensor height and higher in negative sensor height compared to the reference height. Linear regression analyses revealed significant correlations between height difference and FFR, observed among all coronary arteries, as well as between the height difference and Pd-aortic pressure mismatch. Subtracting 0.622 mmHg/cm height difference from Pd could correct the expected hydrostatic pressure influence.

CONCLUSION

Hydrostatic pressure variation resulting from sensor height influenced FFR values might affect interpretation during FFR assessment.

The assessment of coronary artery disease in patients with end-stage renal disease

Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality among patients with end-stage renal disease (ESRD). Clustering of traditional atherosclerotic and non-traditional risk factors drive the excess rates of coronary and non-coronary CVD in patients with ESRD. Coronary artery disease (CAD) is a key disease process, present in ∼50% of the haemodialysis population ≥65 years of age. Patients with ESRD are more likely to be asymptomatic, posing a challenge to the correct identification of CAD, which is essential for appropriate risk stratification and management. Given the lack of randomized clinical trial evidence in this population, current practice is informed by observational data with a significant potential for bias. For this reason, the most appropriate approach to the investigation of CAD is the subject of considerable discussion, with practice patterns largely varying between different centres. Traditional imaging modalities are limited in their diagnostic accuracy and prognostic value for cardiac events and survival in patients with ESRD, demonstrated by the large number of adverse cardiac outcomes among patients with negative test results. This review focuses on the current understanding of CAD screening in the ESRD population, discussing the available evidence for the use of various imaging techniques to refine risk prediction, with an emphasis on their strengths and limitations.