Comparison of coronary flow reserve and fractional flow reserve in patients with versus without diabetes mellitus and having elective percutaneous coronary intervention and abciximab therapy (from the PREDICT Trial)

The Effect of Diabetes on Prognosis Following Myocardial Infarction Treated with Primary Angioplasty and Potent Antiplatelet Therapy

PURPOSE

To investigate the prognostic significance of diabetes mellitus (DM) in patients with high risk acute myocardial infarction (AMI) treated with primary percutaneous coronary intervention (pPCI) in the era of potent antithrombotics.

METHODS

Data from 1230 ST-segment elevation myocardial infarction (STEMI) patients enrolled in the PRAGUE-18 (prasugrel vs. ticagrelor in pPCI) study were analyzed. Ischemic and bleeding event rates were calculated for patients with and without diabetes. The independent impact of diabetes on outcomes was evaluated after adjustment for outcome predictors.

RESULTS

The prevalence of DM was 20% (N = 250). Diabetics were older and more often female. They were more likely to have hypertension, hyperlipoproteinemia, multivessel coronary disease and left main disease, and be obese. The primary net-clinical endpoint (EP) containing death, spontaneous nonfatal MI, stroke, severe bleeding, and revascularization at day 7 occurred in 6.1% of patients with, and in 3.5% of patients without DM (HR 1.8; 95% CI 0.978-3.315; P = 0.055). At one year, the key secondary endpoint defined as cardiovascular death, spontaneous MI, or stroke occurred in 8.8% with, and 5.5% without DM (HR 1.621; 95% CI 0.987-2.661; P = 0.054). In those with DM the risk of total one-year mortality (6.8% vs. 3.9% (HR 1.773; 95% CI 1.001-3.141; P = 0.047)) and the risk of nonfatal reinfarction (4.8% vs. 2.2% (HR 2.177; 95% CI 1.077-4.398; P = 0.026)) were significantly higher compared to in those without DM. There was no risk of major bleeding associated with DM (HR 0.861; 95% CI 0.554-1.339; P = 0.506). In the multivariate analysis, diabetes was independently associated with the one-year risk of reinfarction (HR 2.176; 95% Confidence Interval, 1.055-4.489; p = 0.035).

CONCLUSION

Despite best practices STEMI treatment, diabetes is still associated with significantly worse prognoses, which highlights the importance of further improvements in the management of this high-risk population.

Is ischemia the only factor predicting cardiovascular outcomes in all diabetes mellitus patients?

Diabetes mellitus (DM) is associated with an excess in cardiovascular morbidity and mortality, and is characterized by increased rates of coronary artery disease. Furthermore, once atherosclerosis is established, this is associated with an increased extent, complexity and a more rapid progression than seen in non-DM patients. Ischemia is the single most important predictor of future hard cardiac events and ischemia correction remains the cornerstone of current revascularization strategies. However recent data suggests that, in DM patients, coronary atherosclerosis despite the absence of ischemia, detected by either invasive or non-invasive methods, may not be associated with the same low risk of future cardiac events as seen in non-DM patients. This review seeks to examine the current evidence supporting an ischemia driven revascularization strategy, and to challenge the notion that ischemia is the only clinically relevant factor in the prediction of cardiovascular outcomes in all-comer DM patients. Specifically, we examine whether in DM patients certain characteristics beyond ischemia, such as microvascular disease, coronary atherosclerosis burden, progression and plaque composition, may need to be considered for a more refined risk stratification in these high-risk patients.

Clinical outcomes of deferred revascularisation using fractional flow reserve in patients with and without diabetes mellitus

Objective

Deferred revascularisation based upon fractional flow reserve (FFR >0.80) is associated with a low incidence of target lesion failure (TLF). Whether deferred revascularisation is also as safe in diabetes mellitus (DM) patients is unknown.

Methods

All DM patients and the next consecutive Non-DM patients who underwent a FFR-assessment between 1/01/2010 and 31/12/2013 were included, and followed until 1/07/2015. Patients with lesions FFR >0.80 were analysed according to the presence vs. absence of DM, while patients who underwent index revascularisation in FFR-assessed or other lesions were excluded. The primary endpoint was the incidence of TLF; a composite of target lesion revascularisation (TLR) and target vessel myocardial infarction (TVMI).

Results

A total of 250 patients (122 DM, 128 non-DM) who underwent deferred revascularisation of all lesions (FFR >0.80) were compared. At a mean follow up of 39.8 ± 16.3 months, DM patients compared to non-DM had a higher TLF rate, 18.1 vs 7.5 %, logrank p ≤ 0.01, Cox regression-adjusted HR 3.65 (95 % CI 1.40–9.53, p < 0.01), which was largely driven by a higher incidence of TLR (17.2 vs. 7.5 %, HR 3.52, 95 % CI 1.34–9.30, p = 0.01), whilst a non-significant but numerically higher incidence of TVMI (6.1 vs. 2.0 %, HR 3.34, 95 % CI 0.64–17.30, p = 0.15) was observed.

Conclusions

This study, the largest to directly compare the clinical outcomes of FFR-guided deferred revascularisation in patients with and without DM, shows that DM patients are associated with a significantly higher TLF rate. Whether intravascular imaging, additional invasive haemodynamics or stringent risk factor modification may impact on this higher TLF rate remains unknown.

Flow restoration post revascularization predicted by stenosis indexes: sensitivity to hemodynamic variability

The expected blood flow improvement following a coronary intervention is inversely related to the stenotic-to-normal flow ratio Qs/Qn. Since Qn cannot be measured prior to intervention, treatment decisions rely on stenosis-severity indexes, e.g., area stenosis (%AS), hyperemic stenosis resistance (HSR), and fractional flow reserve (FFR), where treatment cut-off levels have been established for each index based on presence of inducible ischemia. Here, we studied the dependence of these indexes-predicted Qs/Qn under physiological perturbations of stenosis features and of hemodynamic and mechanical conditions. Dynamic coronary flow was simulated based on measured coronary morphometric data and a physics-based computational model. Simulations were used to evaluate the relationship between each index level and Qs/Qn. Under each perturbation, an independence measure (IM) was calculated for each index based on the relative change in Qs/Qn associated with each perturbation. The results show that while %AS prediction of Qs/Qn is largely independent (IM > 90%) of physiological changes in heart rate, venous pressure, and lesion length and location on the epicardial tree, HSR is also independent of changes in left ventricle pressure. FFR-predicted Qs/Qn is also independent of changes in aortic pressure, blood hematocrit, and stenotic vessel stiffness. Nevertheless, independence of all indexes is substantially compromised (IM < 70%) under changes in vasculature stiffness. Specifically, a physiological stiffening elevates Qs/Qn value by 21% at the FFR cut-off value (0.75). These findings suggest that the current FFR cut-off value for treatment of stenotic lesions overestimates the benefit of coronary intervention in patients with a stiffer coronary vasculature (e.g., diabetics, hypertensives).

Is discordance of coronary flow reserve and fractional flow reserve due to methodology or clinically relevant coronary pathophysiology?

OBJECTIVES

The purpose of this study was to determine whether observed discordance between coronary flow reserve (CFR) and fractional flow reserve (FFR) is due to methodology or reflects basic coronary pathophysiology.

BACKGROUND

Despite the clinical importance of coronary physiological assessment, relationships between its 2 most common tools, CFR and FFR, remain poorly defined.

METHODS

The worst CFR and stress relative uptake were recorded from 1,500 sequential cardiac positron emission tomography cases from our center. From the literature, we assembled all combined, invasive CFR-FFR measurements, including a subset before and after angioplasty. Both datasets were compared with a fluid dynamic model of the coronary circulation predicting relationships between CFR and FFR for variable diffuse and focal narrowing.

RESULTS

A modest but significant linear relationship exists between CFR and FFR both invasively (r = 0.34, p < 0.001) and using positron emission tomography (r = 0.36, p < 0.001). Most clinical patients undergoing CFR or FFR measurements have diffusely reduced CFR consistent with diffuse atherosclerosis or small-vessel disease. The theoretical model predicts linear relationships between CFR and FFR for progressive stenosis with slopes dependent on diffuse narrowing, matching observed data. Reported changes in CFR and FFR with angioplasty agree with model predictions of removing focal stenosis but leaving diffuse disease. Although CFR-FFR concordance is common, discordance is due to dominant or absent diffuse versus focal disease, reflecting basic pathophysiology.

CONCLUSIONS

CFR is linearly related to FFR for progressive stenosis superimposed on diffuse narrowing. The relative contributions of focal and diffuse disease define the slope and values along the linear CFR and FFR relationship. Discordant CFR and FFR values reflect divergent extremes of focal and diffuse disease, not failure of either tool. With such discordance observed by invasive and noninvasive techniques and also fitting fluid dynamic predictions, it reflects clinically relevant basic coronary pathophysiology, not methodology.

Riboflavin alleviates cardiac failure in Type I diabetic cardiomyopathy

Heart failure (HF) is a common and serious comorbidity of diabetes. Oxidative stress has been associated with the pathogenesis of chronic diabetic complications including cardiomyopathy. The ability of antioxidants to inhibit injury has raised the possibility of new therapeutic treatment for diabetic heart diseases. Riboflavin constitutes an essential nutrient for humans and animals and it is an important food additive. Riboflavin, a precursor of flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), enhances the oxidative folding and subsequent secretion of proteins. The objective of this study was to investigate the cardioprotective effect of riboflavin in diabetic rats. Diabetes was induced in 30 rats by a single injection of streptozotocin (STZ) (70 mg /kg). Riboflavin (20 mg/kg) was orally administered to animals immediately after induction of diabetes and was continued for eight weeks. Rats were examined for diabetic cardiomyopathy by left ventricular (LV) remadynamic function. Myocardial oxidative stress was assessed by measuring the activity of superoxide dismutase (SOD), the level of malondialdehyde (MDA) as well as heme oxygenase-1 (HO-1) protein level. Myocardial connective tissue growth factor (CTGF) level was measured by Western blot in all rats at the end of the study. In the untreated diabetic rats, left ventricular systolic pressure (LVSP) rate of pressure rose (+dp/dt), and rate of pressure decay (−dp/dt) were depressed while left ventricular end-diastolic pressure (LVEDP) was increased, which indicated the reduced left ventricular contractility and slowing of left ventricular relaxation. The level of SOD decreased, CTGF and HO-1 protein expression and MDA content rose. Riboflavin treatment significantly improved left ventricular systolic and diastolic function in diabetic rats, there were persistent increases in significant activation of SOD and the level of HO-1 protein, and a decrease in the level of CTGF. These results suggest that riboflavin treatment ameliorates myocardial function and improves heart oxidant status, whereas raising myocardial HO-1 and decreasing myocardial CTGF levels have beneficial effects on diabetic cardiomyopathy.

Importance of diffuse atherosclerosis in the functional evaluation of coronary stenosis in the proximal-mid segment of a coronary artery by myocardial fractional flow reserve measurements

The objective of this study was to evaluate the impact of diffuse coronary atherosclerosis on the functional evaluation of moderate coronary lesions in the proximal-mid segment of a coronary artery and its clinical implications. This was a prospective study including 100 consecutive patients with a moderate lesion (45 ± 9% diameter stenosis) in the proximal-mid coronary segment who were evaluated with fractional flow reserve (FFR) measurement. No patient had any other angiographic stenosis distal to the evaluated coronary stenosis. FFR measurements were obtained just distal (~2 to 3 cm) to the lesion (FFR proximal measurement [FFR-PM]) and as distally as possible in the artery (FFR distal measurement [FFR-DM]) after administration of the same dose of intracoronary adenosine. Thirty-nine patients underwent dipyridamole or exercise myocardial single-photon emission computed tomography within 3 months of the FFR study. Mean FFR-PM was significantly higher compared to FFR-DM (0.84 ± 0.08 vs 0.78 ± 0.09, median gradient 0.06, 25th to 75th interquartile range 0.02 to 0.10, p <0.0001). FFR-DM was <0.75 in 33% of patients with FFR-PM ≥0.75, leading to the decision of revascularization in these patients. Performing FFR measurement in the left main/left anterior descending artery predicted a higher gradient between FFR-DM and FFR-PM (odds ratio 4.58, 95% confidence interval 1.4 to 15.03, p = 0.007). FFR-DM exhibited a better correlation with results of myocardial single-photon emission computed tomography compared to FFR-PM (kappa 0.33 vs 0.22, p <0.0001). In conclusion, significant differences between FFR-DM and FFR-PM were observed in patients with moderate coronary stenosis in the proximal-mid segment of a coronary artery, with FFR-DM exhibiting a better correlation with results of noninvasive functional tests. These differences influenced the treatment decision in about 1/3 of patients and highlight the potential clinical relevance of coronary pressure wire positioning for functional evaluation of lesions in the proximal-mid segment of the coronary arteries.

Differential effect of biventricular and right ventricular DDD pacing on coronary flow reserve in patients with ischemic cardiomyopathy

CRT and Coronary Flow Reserve.

BACKGROUND

Cardiac resynchronization therapy (CRT) has become a mainstay in heart failure management. There are also indications that upgrading of existing pacemakers to CRT systems may be of benefit. The aim of this study was to assess the effect of biventricular (BiV), compared with right ventricular (RV), pacing, on coronary flow reserve (CFR), in patients with ischemic cardiomyopathy.

METHODS AND RESULTS

From our database of heart failure patients implanted with BiV pacemakers, 20 patients (10 responders and 10 non-responders to CRT) were randomly selected. Left anterior descending artery coronary flow reserve was measured invasively, under BiV and RV pacing, using intracoronary adenosine to induce hyperemia. In all the 20 patients, there was a significant difference in the pairwise comparison between CFR recorded during BiV and RV pacing (mean difference 0.15, 95% confidence interval 0.07-0.23, P = 0.001). When comparing responders to non-responders, there was a significant difference as to the effect of BiV, compared with RV, pacing on CFR: mean difference (BiV minus RV CFR) was 0.26 ± 0.06 (95% confidence interval 0.13-0.39; P = 0.002), while in non-responders the difference was 0.04 ± 0.03 (95% confidence interval -0.02 to 0.10; P = 0.168).

CONCLUSION

BiV pacing is overall associated to higher CFR, compared with RV DDD pacing. This difference is almost exclusively attributable to the beneficial effect of CRT on coronary flow reserve in CRT-responders. This effect may contribute to the beneficial action of resynchronization in the failing heart and can be viewed in the context of reports of the usefulness of upgrading RV pacemakers to CRT systems.

Azelnidipine protects myocardium in hyperglycemia-induced cardiac damage

Background

Azelnidipine (AZL), a long-acting dihydropyridine-based calcium antagonist, has been recently approved and used for treating ischemic heart disease and cardiac remodeling after myocardial infarction, however, its effect on hyperglycemia-induced cardiac damage has not been studied.

Methods

This study examined the effect of AZL on circulating markers of cardiac damage, altered lipid and cytokines profile and markers of oxidative stress including homocysteine in diabetic rats.

Results

STZ induced diabetes caused a significant increase in blood glucose levels. It also resulted in an increase in the levels of homocysteine and cardiac damage markers, like Troponin-1, CK-MB, CK-NAC, uric acid, LDH and alkaline phosphatase. Moreover, there was an increase in the levels of proinflammatory cytokines like TNF-α, IFN-γ, and TGF-β and decrease in the levels of IL-4 and IL-10. Additionally, there was increase in the levels of cholesterol, triglycerides, LDL, VLDL and a decrease in HDL in these animals. There was an altered antioxidant enzyme profile which resulted in a notable increase in the levels of oxidative stress markers like lipid peroxides, nitric oxide and carbonylated proteins. Compared with the untreated diabetic rats, AZL treatment significantly reduced the levels of troponin-1 (P < 0.05), CK-MB (P < 0.05), CK-NAC (P < 0.05), uric acid (P < 0.05), LDH (P < 0.05) and alkaline phosphatase (P < 0.05). It also reduced the levels of the TNF-α (P < 0.05), IFN-γ (P < 0.05), and TGF-β (P < 0.05) and increased the levels of IL-4 (P < 0.05). A significant decrease in the serum cholesterol (P < 0.05), triglycerides (P < 0.05), LDL (P < 0.05), VLDL (P < 0.05) and a significant rise in levels of HDL (P < 0.05) was also observed. Treatment with AZL corrected the distorted antioxidant enzyme profile resulting in a significant decrease in the levels of lipid peroxides, nitric oxide and carbonylated proteins.

Conclusion

Our results indicate that AZL treatment can reduce the risk of hyperglycemia induced metabolic disorders and its role can be further extended to explore its therapeutic potential in diabetic patients with cardiac complications.

Exercise-induced delayed onset of left ventricular early relaxation in association with coronary microcirculatory dysfunction in patients with diabetes mellitus

BACKGROUND

The initiation of ventricular diastole is an energy-dependent phase of cardiac cycle. Delayed onset of left ventricular (LV) relaxation has been proposed to identify myocardial ischemia. Diabetes mellitus (DM) is known to be associated with coronary microangiopathy, but its influence on LV early relaxation is not established.

METHODS AND RESULTS

Ninety-two subjects consisting of 70 DM patients without overt cardiac disease and 22 normal controls were evaluated. Using strain rate imaging, time from R-wave on the electrocardiogram to onset of LV relaxation (Tr) was measured at rest and peak exercise. Using myocardial contrast echocardiography, myocardial blood flow (MBF) was measured at rest and peak exercise, enabling MBF reserve. Tr at rest was similar between DM patients and controls, but Tr at peak exercise was significantly longer in DM patients than controls. MBF reserve was significantly reduced in DM patients compared with controls. There was a significant negative correlation between Tr at peak exercise and MBF reserve. In a multivariate analysis, MBF reserve was an independent determinant of Tr at peak exercise.

CONCLUSIONS

This study demonstrates that DM patients have exercise-induced delayed onset of LV relaxation in association with impaired coronary microcirculatory function in the absence of coexistent heart disease.

Selective endothelin A-receptor blockade attenuates coronary microvascular dysfunction after coronary stenting in patients with type 2 diabetes

BACKGROUND

Endothelin-1 may be involved in the development of diabetic microangiopathy. We studied the effect of endothelin-1 blockade on myocardial microcirculation during coronary stenting.

PATIENTS AND METHODS

Patients with type 2 diabetes and stable coronary artery disease undergoing elective percutaneous coronary intervention (PCI) were randomized to bolus dose of 500 mg bosentan (n = 4), a dual endothelin receptor blocker, or intracoronary administration of 0.03 mmol BQ123 (n = 6), a selective endothelin A-receptor blocker, or placebo (n = 5), respectively. Coronary flow reserve (CFR) was measured immediately post-PCI. CFR was also measured in five nondiabetic controls post-coronary stenting.

RESULTS

Patients in the placebo group had (P < 0.05) lower values of CFR (2.3 +/- 1.2) as compared to those who received endothelin blockade (n = 10; 3.1 +/- 0.7) and nondiabetic controls (4.9 +/- 2.3). Patients who received BQ123 showed significantly higher CFR (3.3 +/- 0.5; P < 0.05) as compared to those on placebo. Nondiabetic patients had significantly higher CFR as compared to patients with diabetes (4.9 +/- 2.3 and 2.8 +/- 1.0, respectively; P < 0.05).

CONCLUSION

Coronary microvascular dysfunction is present during coronary stenting in patients with type 2 diabetes and may be reversed by selective endothelin A-receptor blockade. Targeting endothelin system may be of importance in protecting the myocardium against ischemic events during elective PCI in type 2 diabetic patients.