Relationship between HgbA1c and myocardial blood flow reserve in patients with type 2 diabetes mellitus: noninvasive assessment using real-time myocardial perfusion echocardiography

Exploring the Predictors of the Discrepancy Between Quantitative Flow Ratio and Fractional Flow Reserve Measurements

BACKGROUND

Quantitative flow ratio is a novel technology for the functional assessment of intermediate coronary stenoses. The authors sought to explore the influence of diabetes mellitus on the application of quantitative flow ratio and predictors of discrepancies between quantitative flow ratio and fractional flow reserve.

METHODS

Quantitative flow ratio was calculated in 224 patients (317 vessels) who underwent fractional flow reserve measurement by professional technicians blinded to fractional flow reserve value. Patients were divided into the diabetes mellitus group and the non-diabetes mellitus group. The diagnostic performance of quantitative flow ratio was assessed using fractional flow reserve as a reference.

RESULTS

Good correlation and agreement between quantitative flow ratio and fractional flow reserve can be found in the diabetes mellitus group (r = 0.834, P <.001; mean difference: 0.007 ± 0.108). Prior myocardial infarction showed a statistically significant association with increased classification discrepancy between quantitative flow ratio and fractional flow reserve (odds ratio 3.16 (95% confidence interval: 1.29-7.75), P =.01). The area under the receiver-operating characteristic curve of quantitative flow ratio showed no significant difference in diabetes mellitus and non-diabetes mellitus groups, hemoglobin A1c ≥ 7% and hemoglobin A1c < 7% groups, diabetic duration ≥ 10 years and diabetic duration < 10 years groups (area under receiver-operating characteristic curve: 0.90 (95% confidence interval: 0.84-0.94) vs. 0.92 (95% confidence interval: 0.87-0.96), P =.54; 0.89 (95% confidence interval: 0.81-0.95) vs. 0.92 (95% confidence interval: 0.81-0.97), P =.65; 0.88 (95% confidence interval: 0.79-0.94) vs. 0.89 (95% confidence interval: 0.79-0.96), P =.83; respectively).

CONCLUSIONS

Clinical application of quantitative flow ratio is not limited to diabetic patients. The relationship between prior myocardial infarction and quantitative flow ratio needs to be further developed.

Characteristics of Myocardial Perfusion in Type 2 Diabetes Mellitus and Its Association with Left Ventricular Diastolic Dysfunction: A Study of Myocardial Contrast Echocardiography

Background

Diabetic cardiomyopathy (DCM) will gradually progress to heart failure without intervention. The timely identification of left ventricular diastolic dysfunction (LVDD) in the early stage and active intervention helps delay the onset of heart failure. Although myocardial contrast echocardiography (MCE) allows an accurate evaluation of myocardial perfusion (MP), the characteristics of MP in early-stage or even sub-clinical LVDD are still unclear.

Objective

This study aims to reveal the characteristics of MP in asymptomatic and normotensive patients with type 2 diabetes mellitus (T2DM) using MCE and investigate its association with LVDD development.

Methods

A total of 327 T2DM patients were retrospectively analyzed. Patients diagnosed with LVDD were included in the LVDD+ group (n = 76), and those with normal left ventricular diastolic function were included in the LVDD- group (n = 251). The clinical characteristics, general echocardiographic findings, and MCE parameters were compared between the two groups. The accuracy of MCE parameters in the diagnosis of LVDD and their correlations with characteristics of T2DM were evaluated.

Results

In the LVDD+ group, the A×β (derived from the replenishment curve of MCE, presenting myocardial blood flow) was significantly lower, and the HbA1c and diabetes duration were significantly higher compared to the LVDD- group (all P < 0.05). The decrease of A×β helped warn the occurrence of LVDD although it was not suitable for the independent diagnosis of LVDD (AUC = 0.745). A×β was negatively correlated with diabetes duration and HbA1c (r = -0.350 and -0.226, both P < 0.001).

Conclusion

MCE was feasible for detecting MP abnormalities in asymptomatic T2DM patients. Although the A×β values of T2DM patients with subclinical LVDD were better than those with diagnosed LVDD, it impaired with the increase of HbA1c and diabetes duration. It suggested that MCE might be useful for monitoring glycemic control in T2DM patients with DCM.

Feasibility of Real-Time Myocardial Contrast Echocardiography to Detect Cardiac Allograft Vasculopathy in Pediatric Heart Transplant Recipients

BACKGROUND

Cardiac allograft vasculopathy (CAV) is an important adverse prognostic factor for pediatric heart transplant (HT) recipients. Invasive coronary angiography (ICA) is the gold standard for CAV detection but lacks sensitivity for early microvascular changes and cumulative radiation exposure is of concern. Real-time myocardial contrast echocardiography (RTMCE) using ultrasound enhancing (contrast) agents performed during dobutamine stress echocardiography (DSE) can assess myocardial function, perfusion, and microvascular integrity. The objective of this study was to determine the safety and feasibility of RTMCE during DSE to detect CAV in a pediatric HT population.

METHODS

HT patients 10-21 years of age were recruited to undergo DSE with RTMCE to determine technical feasibility, test tolerability and adverse event rate, and detection of perfusion defects compared with ICA-detected CAV. Thirty-six patients from two centers were enrolled, with a mean age 13.5 ± 4.3 years; 21 (58%) were male. Wall motion and myocardial perfusion were qualitatively assessed and compared with ICA findings of CAV. Myocardial blood flow (MBF) at rest and peak stress was quantified, and myocardial blood flow reserve (MBFR) was defined as the ratio of peak to rest MBF.

RESULTS

Five (14%) patients had CAV by ICA, two with obstructive disease and three with mild CAV. Real-time myocardial contrast echocardiography was feasible in 32 (89%) patients. Three patients had wall motion defects, including one with a mixed defect and two with fixed defects. A perfusion abnormality was present in five patients, two of whom had obstructive CAV and one with mild CAV. Sensitivity and specificity of RTMCE for CAV detection were 60% and 94%, respectively, and diagnostic accuracy was 89%. MBFR assessment was feasible in 20 (63%) patients. The mean MBFR was 3.4 ± 0.7. Patients with CAV had lower MBFR than those without (2.0 ± 0.2 vs 3.7 ± 0.8; P < .01). There were no serious adverse events related to RTMCE.

CONCLUSIONS

Dobutamine stress RTMCE appears to be safe and feasible for the assessment of CAV in pediatric HT recipients. Further assessment is warranted to determine whether this noninvasive technique could provide a reliable alternative to ICA.

Subclinical Diastolic Dysfunction and Its Correlation with Laboratory Parameters in Type 2 Diabetes Mellitus in India: A Case Control Study

Background: This study was conducted to evaluate left ventricular dysfunction in diabetics and to find correlation with glycemic control and biochemical parameters compared to non-diabetic population. Methods: Thirty type 2 diabetics and thirty nondiabetic controls were recruited. Age, sex, body mass index of the controls were matched. Results: Mean duration of diabetes mellitus in study population was 10.97± 4.01years. Among study population both cases and controls had ejection fraction >55%( no systolic dysfunction). Among cases(n=16) 53.3% were having mean E/A ratio <1 and(n=14) 46.67% were had mean E/A ratio >1. In controls all of them had mean E/A ratio above 1. This difference of mean E/A ratio among cases and controls was statistically significant (p<0.001). Among patients with diabetes, 9.09% cases with a HbA1cbetween 6-7%, 33.33% between 7.1-8%, respectively 100% of cases with HbA1c>8.1% had diastolic dysfunction the differences between groups being statistically significant (p<0.001). Low density lipoprotein( LDL) was weakly and negative correlated with E/A ratio (r = - 0.38) while fasting blood sugar (r = -0.53) respectively Hemoglobin A1c (r = -0.66) were moderately and negatively correlated. All these correlations were statistically significant. Conclusion: Subclinical diastolic dysfunction is prevalent among diabetic population. Diastolic dysfunction in patients with diabetes was correlated with FBS, HbA1C and LDL.

Longer diabetes duration reduces myocardial blood flow in remote myocardium assessed by dynamic myocardial CT perfusion

AIMS

To investigate the relationship of type 2 diabetes duration and myocardial blood flow (MBF) assessed by myocardial CT perfusion.

MATERIALS AND METHODS

We prospectively included 140 patients with type 2 diabetes who underwent dynamic myocardial CT perfusion exam. MBF of the remote myocardium was calculated using the deconvolution technique and the Voronoi method. The relationships of MBF and diabetic duration, diabetic complications, conventional risk factors, coronary calcium, and coronary stenosis were assessed by logistic regression analysis.

RESULTS

A weak but significantly negative relationship was present between diabetes duration and MBF (R² = 0.05, p < 0.01). The average MBF of patients with a duration of >8 years was 13% lower than that of the remaining patients (1.11 ± 0.35 vs 1.28 ± 0.27 ml min^-1 g^-1, p < 0.01). Duration of one year was associated with a 6% increased risk for low MBF (<1.18 ml min^-1 g^-1) (odds ratio 1.06, 95% confidence interval 1.01-1.12, p < 0.05). Calcium score was also a significant factor for low MBF (odds ratio 1.08 (per 100 Agatston units), 95% confidence interval 1.01-1.17, p < 0.05).

CONCLUSION

Longer diabetes duration is associated with lower MBF independent of conventional cardiac risk factors or the presence of coronary stenosis.

The clinical use of stress echocardiography in ischemic heart disease

Stress echocardiography is an established technique for the assessment of extent and severity of coronary artery disease. The combination of echocardiography with a physical, pharmacological or electrical stress allows to detect myocardial ischemia with an excellent accuracy. A transient worsening of regional function during stress is the hallmark of inducible ischemia. Stress echocardiography provides similar diagnostic and prognostic accuracy as radionuclide stress perfusion imaging or magnetic resonance, but at a substantially lower cost, without environmental impact, and with no biohazards for the patient and the physician.

The evidence on its clinical impact has been collected over 35 years, based on solid experimental, pathophysiological, technological and clinical foundations. There is the need to implement the combination of wall motion and coronary flow reserve, assessed in the left anterior descending artery, into a single test. The improvement of technology and in imaging quality will make this approach more and more feasible. The future issues in stress echo will be the possibility of obtaining quantitative information translating the current qualitative assessment of regional wall motion into a number. The next challenge for stress echocardiography is to overcome its main weaknesses: dependance on operator expertise, the lack of outcome data (a widesperad problem in clinical imaging) to document the improvement of patient outcomes. This paper summarizes the main indications for the clinical applications of stress echocardiography to ischemic heart disease.

Time course of cardiometabolic alterations in a high fat high sucrose diet mice model and improvement after GLP-1 analog treatment using multimodal cardiovascular magnetic resonance

BACKGROUND

Cardiovascular complications of obesity and diabetes are major health problems. Assessing their development, their link with ectopic fat deposition and their flexibility with therapeutic intervention is essential. The aim of this study was to longitudinally investigate cardiac alterations and ectopic fat accumulation associated with diet-induced obesity using multimodal cardiovascular magnetic resonance (CMR) in mice. The second objective was to monitor cardiac response to exendin-4 (GLP-1 receptor agonist).

METHODS

Male C57BL6R mice subjected to a high fat (35 %) high sucrose (34 %) (HFHSD) or a standard diet (SD) during 4 months were explored every month with multimodal CMR to determine hepatic and myocardial triglyceride content (HTGC, MTGC) using proton MR spectroscopy, cardiac function with cine cardiac MR (CMR) and myocardial perfusion with arterial spin labeling CMR. Furthermore, mice treated with exendin-4 (30 μg/kg SC BID) after 4 months of diet were explored before and 14 days post-treatment with multimodal CMR.

RESULTS

HFHSD mice became significantly heavier (+33 %) and displayed glucose homeostasis impairment (1-month) as compared to SD mice, and developed early increase in HTGC (1 month, +59 %) and MTGC (2-month, +63 %). After 3 months, HFHSD mice developed cardiac dysfunction with significantly higher diastolic septum wall thickness (sWtnD) (1.28 ± 0.03 mm vs. 1.12 ± 0.03 mm) and lower cardiac index (0.45 ± 0.06 mL/min/g vs. 0.68 ± 0.07 mL/min/g, p = 0.02) compared to SD mice. A significantly lower cardiac perfusion was also observed (4 months:7.5 ± 0.8 mL/g/min vs. 10.0 ± 0.7 mL/g/min, p = 0.03). Cardiac function at 4 months was negatively correlated to both HTGC and MTGC (p < 0.05). 14-day treatment with Exendin-4 (Ex-4) dramatically reversed all these alterations in comparison with placebo-treated HFHSD. Ex-4 diminished myocardial triglyceride content (-57.8 ± 4.1 %), improved cardiac index (+38.9 ± 10.9 %) and restored myocardial perfusion (+52.8 ± 16.4 %) under isoflurane anesthesia. Interestingly, increased wall thickness and hepatic steatosis reductions were independent of weight loss and glycemia decrease in multivariate analysis (p < 0.05).

CONCLUSION

CMR longitudinal follow-up of cardiac consequences of obesity and diabetes showed early accumulation of ectopic fat in mice before the occurrence of microvascular and contractile dysfunction. This study also supports a cardioprotective effect of glucagon-like peptide-1 receptor agonist.

Intracoronary administration of nicorandil during primary percutaneous coronary intervention: Impact on restoration of regional myocardial perfusion in reperfused myocardium during the subacute phase of myocardial infarction

Background

The impact of nicorandil as adjunctive therapy for percutaneous coronary intervention (PCI) in patients with ST-elevation myocardial infarction (STEMI) is controversial. We performed ¹⁵O-labeled water positron emission tomography (PET) to quantify regional myocardial perfusion in patients with STEMI who received nicorandil or no adjunctive therapy during PCI.

Methods

PCI was performed within 8 h after STEMI onset in 33 patients. 14 patients received intracoronary nicorandil 2 mg immediately after recanalization of the culprit lesion (Nico group). After 3–4 weeks, PET was performed in which myocardial blood flow (MBF) was measured at baseline and during adenosine triphosphate (ATP)-induced hyperemia. Myocardial vascular resistance (MVR) was calculated for all segments. Data were obtained from the reperfused (Rep) and normal segments (Cont) in each patient.

Results

In patients not given nicorandil (No-Nico group), the MBF was significantly lower in Rep than that in Cont at baseline and during hyperemia (Cont vs. Rep: 0.82 ± 0.14 vs. 0.68 ± 0.11, P = 0.001, ATP-Cont vs. ATP-Rep: 2.00 ± 0.72 vs. 1.52 ± 0.61, P = 0.017), which was restored in the Nico group (Cont vs. Rep: 0.79 ± 0.17 vs. 0.78 ± 0.20; ATP-Cont vs. ATP-Rep: 2.02 ± 0.84 vs. 1.84 ± 0.62). MVR was elevated in Rep at baseline and during hyperemia in the No-Nico group. MVR elevation in Rep was prevented in the Nico group.

Conclusions

¹⁵O-labeled water PET was feasible for segmental analysis of MBF during the subacute phase of STEMI. It revealed that intracoronary administration of nicorandil to STEMI patients who underwent PCI prevented MVR elevation and thus restored MBF in the reperfused segments to a level similar to that in the normal segments.

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¹⁵O-labeled water positron emission tomography (PET) is a tool to compare directly reperfused segments with normal segments simultaneously in each patient's hearts.

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¹⁵O-labeled water PET permits noninvasive quantitative measurement of myocardial blood flow during the subacute phase of myocardial infarction.

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¹⁵O-labeled water PET detects restoration of myocardial blood flow after intracoronary administration of nicorandil in STEMI patients.