Toya, Takumi

Abstract Background Coronary flow augmentation occurs through the simultaneous interaction and regulation of both endothelium-dependent and endothelium-independent mechanisms. A decrease in coronary flow reserve (CFR) secondary to either mechanism is associated with poor prognosis. However, at the individual level, the integrated impact of these two mechanisms has not been thoroughly investigated. Purpose This study investigated the prognostic implications of an integrated metric, CFRsum, combining endothelium-dependent and -independent CFR. Methods A total of 1441 patients with angina with non-obstructive coronary artery (ANOCA) undergoing coronary reactivity testing were studied. Endothelium-independent CFR was measured during adenosine-induced hyperemia, and endothelium-dependent CFR during intracoronary acetylcholine infusion. CFRsum was calculated by summing these components. Cardiovascular event was defined as composite of cardiovascular death, myocardial infarction, heart failure, and cerebral infarction. Results Our patients had a median age of 51.7 years, 69.0% of whom were female, and their CFRsum was 4.57 [3.88, 5.37]. Patients were divided into three tertile-based groups, and Cox proportional hazards analysis demonstrated that all CFR classes were independent predictors of prognosis, with CFRsum providing the best model fit (Likelihood ratio: 54.62, degrees of freedom: 7, P < 0.001). The Kaplan-Meier curve (Figure) demonstrated a stepwise deterioration in prognosis across CFRsum tertile groups, with lower CFRsum being associated with progressively worse outcomes (p < 0.001). Stratification by follow-up duration (3 years) revealed that patients with middle-range CFRsum exhibited comparable outcomes to those with the highest CFRsum during the early phase (<3y) but significantly worse outcomes in the late phase (≥3y) (P = 0.459 and P < 0.001, respectively). Conclusion CFRsum showed superior prognostic value over traditional CFR metrics in patients with ANOCA, identifying a compensated group with time-varying outcomes. This novel metric improves the assessment of microvascular function and supports better clinical management.

Background: Sex differences in coronary physiology have been reported, particularly with regard to higher resting coronary flow in women. Resting flow is independently associated with clinical outcomes, irrespective of the presence of coronary microvascular dysfunction (CMD), but its sex-specific prognostic significance remains unclear. Aims: This study aimed to compare the prognostic implications of resting flow and CMD between sexes among patients with angina and non-obstructive coronary arteries (ANOCA). Methods: We studied 1194 patients with ANOCA undergoing coronary reactivity testing. Endothelium-independent microvascular function was assessed by coronary flow reserve (CFR) during adenosine-induced hyperemia, and endothelium-dependent function by coronary blood flow (CBF) increase during intracoronary acetylcholine infusion. Endothelium-dependent CMD was defined as <50% CBF increase, and endothelium-independent CMD as CFR <2.5. Cardiovascular events were defined as a composite of all-cause death, myocardial infarction and heart failure. Results: The median age of the study population was 52 years, and 71.1% were women. Resting average peak velocity (rAPV) and baseline CBF (bCBF) were significantly higher in women (p<0.001 and p=0.006, respectively). Survival analysis revealed that both elevated rAPV and bCBF were significantly associated with worse outcomes in men (p<0.001 and p=0.036, respectively, Figure 1), whereas no such associations were observed in women. In Cox proportional hazard analysis, sex showed a significant interaction effect with elevated rAPV (interaction p=0.014). Furthermore, endothelium-independent CMD was significantly associated with adverse outcomes in both men and women (p=0.011 and p=0.004, respectively), whereas endothelium-dependent CMD was significantly associated with prognosis only in men (p=0.006). Among men with endothelium-dependent CMD, the subtype characterized by higher bCBF was particularly associated with worse prognosis (p=0.001, Figure 2). Conclusions: In patients with ANOCA, men had lower resting coronary flow than women. However, its association with adverse outcomes was observed only in men, especially in those with impaired endothelial function. These results suggest that coronary physiology should be interpreted differently by sex, and that clinical decisions should be adjusted accordingly.

Introduction: The endothelium controls coronary blood flow (CBF) by regulating microvascular tone, which is an important index of microcirculatory health. The difference in vasomotor response of the microvasculature between males and females is not well described. Hypothesis: Males and females react differently to different doses of intracoronary (IC) acetylcholine (Ach) injections. Methods: Patients with angina and non-obstructive coronary artery disease (<50% stenosis) that underwent coronary reactivity study were enrolled. A doppler wire was positioned and incremental IC Ach doses were injected (10 -6 , 10 -5 , and 10 -4 mol/L). CBF (mL/min) was then calculated from CAD and doppler-derived flow velocity. Comparisons between the 2 sexes were performed. Results: A total of 1927 patients (mean age 51±13 years, 67% females) were included. Males were significantly younger (49±13 vs 53±12, P<0.0001) than females and had a higher smoking exposure rate (56% vs 41%, P<0.0001). Baseline (B) CBF was significantly lower in males (27.7 [19.2; 40.8] vs 30.2 [20.6; 43.4], P=0.04). The gap between females and males widened the first 2 doses, but then diminished after the highest dose (41.2 [24.5; 67.8] vs 44.5 [25.9; 72.0], P=0.09) (Fig 1A) . On multivariable analyses, female sex was an independent predictor of higher CBF at all doses (Estimate±StdError) (B= 1.14±0.53; 10 -6 : 1.59±0.61; 10 -5 : 2.54±0.82; 10 -4 : 2.70±1.2; P<0.05 for all). When calculating the %ΔCBF, females had a significantly larger augmentation of flow after the first 2 doses of IC Ach (10 -6 : 3 [-14; 24] vs. -2 [-16; 19], P=0.02; 10 -5 : 21 [-7;68] vs. 12 [-10; 50], P=0.003). However, with the highest Ach dose, there was an equalization of overall augmentation (10 -4 : 49 [-1; 109] vs. 46 [-5; 106], P=0.46) (Fig 1B). Conclusions: Females had higher CBF regardless of given Ach concentration. Females have a higher sensitivity to Ach at smaller doses, while males exhibit a greater vasodilatory reaction at higher doses.

Introduction: Coronary microvascular dysfunction (CMD) is associated with increased morbidity and mortality. Anemia is an important predictor of outcomes in several cardiovascular diseases, such as heart failure and coronary artery disease (CAD), however its significance in patients with non-obstructive CAD is not fully elucidated. Hypothesis: We hypothesized that anemia would be associated with CMD and future adverse outcomes. Methods: We enrolled 1334 patients with signs and/or symptoms of ischemia and with non-obstructive CAD (<50% angiographic stenosis) who underwent invasive CMD evaluation and had follow-up data. CMD was defined as coronary flow reserve (CFR) (hyperemic flow/baseline flow as measured by the doppler wire) of ≤2 in response to intracoronary adenosine injection. Anemia was defined as a Hgb < 13.0 g/L in males and <12.0 g/L in females. MACE was defined as any incidence of myocardial infarction, cardiac revascularization (PCI, CABG) and all-cause mortality. Results: Overall mean age was 51.3±12.4 years, 66% were female. Patients with anemia were more likely to be female and have diabetes mellitus. Anemics were more likely to be diagnosed with CMD (Odds Ratio 2.01, 95% Confidence Interval [1.14-3.54]; P = 0.02). This relationship remained significant even after adjusting for cardiovascular risk factors like age, sex, hypertension, diabetes mellitus and dyslipidemia (OR 1.84, 95% CI [1.03-3.29], P = 0.04). Furthermore, patients with anemia were more likely to experience MACE (OR 1.86, 95% CI [1.30-2.66], P = 0.001), independent of possible confounders (OR 1.84, 95% CI [1.27-2.69], P = 0.002). Conclusions: Anemia is an independent predictor of CMD and future adverse cardiovascular events in patients with NOCAD. Moreover, it was associated with an increased risk of future adverse events. Further studies are needed to elucidate whether treatment of anemia in this population translates into outcomes.

Introduction: Changes in coronary artery diameter (CAD) and coronary blood flow (CBF) in reaction to acetylcholine are important surrogates of endothelial health, and abnormalities in these parameters might represent early atherosclerosis. Menopause is associated with an increased risk of coronary artery disease, yet the role of menopause on the endothelium is not well described. Hypothesis: The vasodilatory response of the endothelium to acetylcholine (Ach) decreases after menopause. Methods: A total of 1271 (42% pre-menopausal) females with angina and non-obstructive coronary artery disease (<50% angiographic stenosis) that underwent coronary reactivity study were enrolled. A doppler wire was positioned and incremental Ach doses were injected (10 -6 , 10 -5 , and 10 -4 mol/L). CBF was then calculated from CAD and doppler-derived flow velocity. Comparisons between the pre-and post-menopause groups were performed. Results: Mean age of the pre-menopausal group was 44±10 years, while that of the post-menopausal 59±9 years. Pre-menopausal females had higher baseline CAD as compared to post-menopausal females (2.22 [1.90; 2.65] vs. 2.20 [1.85; 2.55] mm, P=0.03). However, this difference was nullified with subsequent doses of Ach (Figure 1A&B ). Pre-menopausal females had a higher baseline CBF than post-menopausal females (32.1 [21.7; 44.9] vs. 29.2 [19.8; 42.0] mL/min; P=0.01). This difference progressively increased with successive doses of Ach (10 -4 :49.5 [30.3; 77.0] vs. 41.7 [24.4; 69.0] mL/min; P=0.0002), revealing a greater microvascular vasodilatory response in pre-menopausal females (Cumulative %ΔCBF after highest dose= 60 [2.6; 122] vs 45 [-4; 98], P=0.002) ( Figure 1C&D ). Conclusions: Premenopausal females have greater sensitivity of the microvascular endothelium to Ach compared to post-menopausal, suggesting a possible role for estrogen in mediating the effect of stress on the microvasculature through the endothelium.

Introduction: Diabetes mellitus and insulin resistance are associated with accelerated vascular injury and progression of coronary atherosclerosis. CD34 + progenitor cells are mobilized and recruited to repair the endothelial and vascular damage. Hypothesis: We hypothesized that the interaction of insulin levels and retention of CD34+ progenitors in the coronary arteries will be different between patients with and without insulin resistance. Methods: In patients with no obstructive coronary artery disease (NOCAD: <40% angiographic stenosis), blood samples were collected concurrently from the proximal aorta and the coronary sinus, and CD34+ cells counted using flow cytometry. CD34+ cells gradient was calculated by subtracting aortic from coronary sinus cell counts, with a higher gradient reflecting lower retention. Patients on antidiabetic medications were excluded. Insulin resistance (IR) was estimated as HOMA-IR index ([insulin]*[glucose]/405)) ≥2. Results: Of 128 patients (mean age 51±11 years, 77% females), 60 (47%) had IR (mean age 51±10 years, 73% females) and 68 (53%) did not (mean age 50±13 years, 79% females). The groups did not differ in age, sex or LDL cholesterol. The IR group had higher BMI and triglyceride levels and lower HDL cholesterol. CD34 + cell gradient correlated directly significantly with insulin levels in patients without IR (r=0.25, p=0.04) (Fig1A) , but inversely in those with IR (r=-0.39, p=0.01) (Fig1B) . Both associations remained significant after adjustment for age, sex, and BMI (IR: r=-0.39, p=0.02; no IR: r=29, p=0.04). Conclusions: In NOCAD patients with IR, higher levels of serum insulin were associated with increased retention of CD34 + cells in the coronary arteries. The current study supports a potential role for CD34 + cells for vascular repair in patients with IR.

Abstract Aims This study aims to identify whether adding peripheral microvascular dysfunction (PMED), a marker of atherosclerosis to established risk scores has an incremental prognostic value for major adverse cardiovascular events (MACE). Methods and results This is a retrospective study of patients who underwent measuring peripheral arterial tonometry from 2006 to 2020. The optimal cut-off value of the reactive hyperaemia index (RHI) that had maximal prognostic value associated with MACE was calculated. Peripheral microvascular endothelial dysfunction was defined as the RHI lower than the cut-off. Traditional cardiovascular risk factors such as age, sex, congestive heart failure, hypertension, diabetes, stroke, and vascular disease were determined to calculate the CHA2DS2-Vasc score. The outcome was MACE defined as myocardial infarction, heart failure hospitalization, cerebrovascular events, and all-cause mortality. A total of 1460 patients were enrolled (average age 51.4 ± 13.6, 64.1% female). The optimal cut-off value of the RHI was 1.83 in the overall population and in females and males was 1.61 and 1.8, respectively. The risk of MACE during 7 [interquartile range (IQR): 5,11] years of follow-up was 11.2%. Kaplan–Meier analysis showed that lower RHI is associated with worse MACE-free survival (P &lt; 0.001). Multivariate Cox proportional hazard analysis, controlling for classic cardiovascular risk factors or risk scores such as CHA2DS2-Vasc and Framingham risk score revealed that PMED is an independent predictor of MACE. Conclusion Peripheral microvascular dysfunction predicts cardiovascular events. Non-invasive assessment of peripheral endothelial function may be useful in early detection and improving the stratification of high-risk patients for cardiovascular events. Lay summary Key findings

BACKGROUND: The financial burden linked to the diagnosis and treatment of patients with chest pain on the health care system is considerable. Angina and nonobstructive coronary artery disease (ANOCA) is common, associated with adverse cardiovascular events, and may lead to repeat testing or hospitalizations. Diagnostic certainty can be achieved in patients with ANOCA using coronary reactivity testing (CRT); however, its financial effect on the patient has not been studied. Our goal was to assess the effect of CRT on health care–related cost in patients with ANOCA. METHODS: Patients with ANOCA who underwent diagnostic coronary angiography (CAG) and CRT (CRT group) were matched to controls who had similar presentation but only underwent a CAG without CRT (CAG group). Standardized inflation-adjusted costs were collected and compared between the 2 groups on an annual basis for 2 years post the index date (CRT or CAG). RESULTS: Two hundred seven CRT and 207 CAG patients were included in the study with an average age of 52.3±11.5 years and 76% females. The total cost was significantly higher in the CAG group as compared with the CRT group ($37 804 [$26 933–$48 674] versus $13 679 [$9447–$17 910]; P <0.001). When costs are itemized and divided based on the Berenson-Eggers Type of Service categorization, the largest cost difference occurred in imaging (any type, including CAG; P <0.001), procedures (eg, percutaneous coronary intervention/coronary artery bypass grafting/thrombectomy) ( P =0.001), and test (eg, blood tests, EKG; P <0.001). CONCLUSIONS: In this retrospective observational study, assessment of CRT in patients with ANOCA was associated with significantly reduced annual total costs and health care utilization. Therefore, the study may support the integration of CRT into clinical practice.