Mohamad Mazen Gafeer

The association between acute mental stress and abnormal left atrial electrophysiology

Acute stress may trigger atrial fibrillation (AF), but the underlying mechanisms are unclear. We examined if acute mental stress results in abnormal left atrial electrophysiology as detected by more negative deflection of P‐wave terminal force in lead V1 (PTFV1), a well‐known marker of AF risk.

High‐Sensitivity Troponin I Levels and Coronary Artery Disease Severity, Progression, and Long‐Term Outcomes

Background The associations between high‐sensitivity troponin I (hsTnI) levels and coronary artery disease (CAD) severity and progression remain unclear. We investigated whether there is an association between hsTnI and angiographic severity and progression of CAD and whether the predictive value of hsTnI level for incident cardiovascular outcomes is independent of CAD severity. Methods and Results In 3087 patients (aged 63±12 years, 64% men) undergoing cardiac catheterization without evidence of acute myocardial infarction, the severity of CAD was calculated by the number of major coronary arteries with ≥50% stenosis and the Gensini score. CAD progression was assessed in a subset of 717 patients who had undergone ≥2 coronary angiograms >3 months before enrollment. Patients were followed up for incident all‐cause mortality and incident cardiovascular events. Of the total population, 11% had normal angiograms, 23% had nonobstructive CAD, 20% had 1‐vessel CAD, 20% had 2‐vessel CAD, and 26% had 3‐vessel CAD. After adjusting for age, sex, race, body mass index, smoking, hypertension, diabetes mellitus history, and renal function, hsTnI levels were independently associated with the severity of CAD measured by the Gensini score (log 2 ß=0.31; 95% confidence interval, 0.18–0.44; P<0.001) and with CAD progression (log 2 ß=0.36; 95% confidence interval, 0.14–0.58; P=0.001). hsTnI level was also a significant predictor of incident death, cardiovascular death, myocardial infarction, revascularization, and cardiac hospitalizations, independent of the aforementioned covariates and CAD severity. Conclusions Higher hsTnI levels are associated with the underlying burden of coronary atherosclerosis, more rapid progression of CAD, and higher risk of all‐cause mortality and incident cardiovascular events. Whether more aggressive treatment aimed at reducing hsTnI levels can modulate disease progression requires further investigation.

Coronary and Peripheral Vasomotor Responses to Mental Stress

Background Coronary microvascular dysfunction may contribute to myocardial ischemia during mental stress (MS). However, the role of coronary epicardial and microvascular function in regulating coronary blood flow (CBF) responses during MS remains understudied. We hypothesized that coronary vasomotion during MS is dependent on the coronary microvascular endothelial function and will be reflected in the peripheral microvascular circulation. Methods and Results In 38 patients aged 59±8 years undergoing coronary angiography, endothelium‐dependent and endothelium‐independent coronary epicardial and microvascular responses were measured using intracoronary acetylcholine and nitroprusside, respectively, and after MS induced by mental arithmetic testing. Peripheral microvascular tone during MS was measured using peripheral arterial tonometry (Itamar Inc, Caesarea, Israel) as the ratio of digital pulse wave amplitude compared to rest (peripheral arterial tonometry ratio). MS increased the rate‐pressure product by 22% (±23%) and constricted epicardial coronary arteries by −5.9% (−10.5%, −2.6%) (median [interquartile range]), P=0.001, without changing CBF. Acetylcholine increased CBF by 38.5% (8.1%, 91.3%), P=0.001, without epicardial coronary diameter change (0.1% [−10.9%, 8.2%], P=not significant). The MS‐induced CBF response correlated with endothelium‐dependent CBF changes with acetylcholine (r=0.38, P=0.03) but not with the response to nitroprusside. The peripheral arterial tonometry ratio also correlated with the demand‐adjusted change in CBF during MS (r=−0.60, P=0.004), indicating similarity between the microcirculatory responses to MS in the coronary and peripheral microcirculation. Conclusions The coronary microvascular response to MS is determined by endothelium‐dependent, but not endothelium‐independent, coronary microvascular function. Moreover, the coronary microvascular responses to MS are reflected in the peripheral microvascular circulation.

Mechanisms underlying the J-curve for diastolic blood pressure: Subclinical myocardial injury and immune activation

BACKGROUND Low diastolic blood pressure (DBP) is associated with increased risk of cardiovascular events. In patients with coronary artery disease (CAD), limitations in coronary blood flow and immune activity are implicated mechanisms, but evidence is lacking. We investigated the association between DBP, biomarkers of myocardial injury, inflammation, immune activation and incident events in patients with CAD. METHODS We studied 2448 adults (mean age 65 ± 12 years, 68% male, median follow-up 4.5 years) with CAD. DBP was categorized into 10 mm Hg increments. Biomarkers of myocardial injury (high sensitivity cardiac troponin-I [hs-cTnI]) and immune activity/inflammation (soluble urokinase plasminogen activator receptor [suPAR]) were dichotomized at their median values. DBP 70-79 mm Hg was used as the referent group, and individuals were followed prospectively for adverse outcomes. RESULTS After adjusting for demographic and clinical covariates, individuals with DBP < 60 mm Hg had increased odds of elevated levels of hs-cTnI (OR = 1.68; 95% CI = 1.07, 2.65) and suPAR (OR = 1.71; 95% CI = 1.10, 2.65) compared to the referent group. Additionally, DBP < 60 mm Hg was associated with increased adjusted risk of cardiovascular death or MI (HR = 2.04; 95% CI = 1.32, 3.16) and all-cause mortality (HR = 2.41; 95% CI = 1.69, 3.45). CONCLUSION In patients with CAD, DBP < 60 mm Hg is associated with subclinical myocardial injury, immune/inflammatory dysregulation and incident events. Aggressive BP control may be harmful in these patients, and further investigation is warranted to determine appropriate BP targets in patients with CAD.

Progenitor Cells and Clinical Outcomes in Patients with Acute Coronary Syndromes

Rationale: Circulating progenitor cells (CPCs) mobilize in response to ischemic injury, but their predictive value remains unknown in acute coronary syndrome (ACS). Objective: We aimed to investigate the number of CPCs in ACS compared with those with stable coronary artery disease (CAD), relationship between bone marrow PCs and CPCs, and whether CPC counts predict mortality in patients with ACS. Methods and Results: In 2028 patients, 346 had unstable angina, 183 had an acute myocardial infarction (AMI), and the remaining 1499 patients had stable CAD. Patients with ACS were followed for the primary end point of all-cause death. CPCs were enumerated by flow cytometry as mononuclear cells expressing a combination of CD34+, CD133+, vascular endothelial growth factor receptor 2+, or chemokine (C-X-C motif) receptor 4+. CPC counts were higher in subjects with AMI compared those with stable CAD even after adjustment for age, sex, race, body mass index, renal function, hypertension, diabetes mellitus, hyperlipidemia, and smoking; CD34+, CD34+/CD133+, CD34+/CXCR4+, and CD34+/VEGFR2+ CPC counts were 19%, 25%, 28%, and 142% higher in those with AMI, respectively, compared with stable CAD. There were strong correlations between the concentrations of CPCs and the PC counts in bone marrow aspirates in 20 patients with AMI. During a 2 (interquartile range, 1.31–2.86)-year follow-up period of 529 patients with ACS, 12.4% died. In Cox regression models adjusted for age, sex, body mass index, heart failure history, estimated glomerular filtration rate, and AMI, subjects with low CD34+ cell counts had a 2.46-fold (95% confidence interval, 1.18–5.13) increase in all-cause mortality, P=0.01. CD34+/CD133+ and CD34+/CXCR4+, but not CD34+/VEGFR2+ PC counts, had similar associations with mortality. Results were validated in a separate cohort of 238 patients with ACS. Conclusions: CPC levels are significantly higher in patients after an AMI compared with those with stable CAD and reflect bone marrow PC content. Among patients with ACS, a lower number of hematopoietic-enriched CPCs are associated with a higher mortality.

Circulating Progenitor Cells and Racial Differences: A Possible Contribution to Health Disparity

Rationale: Blacks compared with whites have a greater risk of adverse cardiovascular outcomes. Impaired regenerative capacity, measured as lower levels of circulating progenitor cells (CPCs), is a novel determinant of adverse outcomes; however, little is known about racial differences in CPCs. Objective: To investigate the number of CPCs, PC-mobilizing factors, PC mobilization during acute myocardial infarction and the predictive value of CPC counts in blacks compared with whites. Methods and Results: CPCs were enumerated by flow cytometry as CD45med+ blood mononuclear cells expressing CD34+, CD133+, VEGF2R+, and CXCR4+ epitopes in 1747 subjects, mean age 58.4±13, 55% male, and 26% self-reported black. Patients presenting with acute myocardial infarction (n=91) were analyzed separately. Models were adjusted for relevant clinical variables. SDF-1&agr; (stromal cell-derived factor-1&agr;), VEGF (vascular endothelial growth factor), and MMP-9 (matrix metallopeptidase-9) levels were measured (n=561), and 623 patients were followed for median of 2.2 years for survival analysis. Blacks were younger, more often female, with a higher burden of cardiovascular risk, and lower CPC counts. Blacks had fewer CD34+ cells (−17.6%; [95% confidence interval (CI), −23.5% to −11.3%]; P<0.001), CD34+/CD133+ cells (−15.5%; [95% CI, −22.4% to −8.1%]; P<0.001), CD34+/CXCR4+ cells (−17.3%; [95% CI, −23.9% to −10.2%]; P<0.001), and CD34+/VEGF2R+ cells (−27.9%; [95% CI, −46.9% to −2.0%]; P=0.04) compared with whites. The association between lower CPC counts and black race was not affected by risk factors or cardiovascular disease. Results were validated in a separate cohort of 411 patients. Blacks with acute myocardial infarction had significantly fewer CPCs compared with whites (P=0.02). Blacks had significantly lower plasma MMP-9 levels (P<0.001) which attenuated the association between low CD34+ and black race by 19% (95% CI, 13%–33%). However, VEGF and SDF-1&agr; levels were not significantly different between the races. Lower CD34+ counts were similarly predictive of mortality in blacks (hazard ratio, 2.83; [95% CI, 1.12–7.20]; P=0.03) and whites (hazard ratio, 1.79; [95% CI, 1.09–2.94]; P=0.02) without significant interaction. Conclusions: Black subjects have lower levels of CPCs compared with whites which is partially dependent on lower circulating MMP-9 levels. Impaired regenerative capacity is predictive of adverse outcomes in blacks and may partly account for their increased risk of cardiovascular events.

Posttraumatic stress disorder is associated with enhanced interleukin-6 response to mental stress in subjects with a recent myocardial infarction

BACKGROUND Posttraumatic Stress Disorder (PTSD) is prevalent among patients who survived an acute coronary syndrome, and is associated with adverse outcomes, but the mechanisms underlying these associations are unclear. Individuals with PTSD have enhanced sensitivity of the noradrenergic system to stress which may lead to immune activation. We hypothesized that survivors of a myocardial infarction (MI) who have PTSD would show an enhanced inflammatory response to acute psychological stress compared to those without PTSD. METHODS Individuals with a verified history of MI within 8 months and a clinical diagnosis of current PTSD underwent a mental stress speech task. Inflammatory biomarkers including interleukin-6 (IL-6), high-sensitivity C reactive protein (HsCRP), matrix metallopeptidase 9 (MMP-9), intercellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM)-1 and monocyte chemoattractant protein (MCP)-1 were measured at rest and 90 min after mental stress. RESULTS Among 271 patients in the study (mean age 51 ± 7 years, 50% female, 60% African-American), the prevalence of PTSD was 12%. Mental stress resulted in a significant increase in IL-6, but the increase was more marked in patients with PTSD (126% increase) than those without (63% increase) (p = 0.001). MCP-1 showed a modest increase with stress which was similar in patients with PTSD (9% increase) and without PTSD (6% increase) (p = 0.35). CRP did not increase with stress in either group. CONCLUSION MI patients with current PTSD exhibit enhanced IL-6 response to psychosocial stress, suggesting a mechanistic link between PTSD and adverse cardiovascular outcomes as well as other diseases associated with inflammation.

Comparison of the Association between High-Sensitivity Troponin I and Adverse Cardiovascular Outcomes in Patients with Versus Without Chronic Kidney Disease

It is unknown whether the association of high-sensitivity troponin I (hs-TnI) with adverse cardiovascular outcomes varies by the presence of chronic kidney disease (CKD). We examined the association of hs-TnI with adverse cardiovascular outcomes in those with and without CKD in 4,107 (mean age, 64 years; 63% men; 20% black) patients from the Emory Cardiovascular Biobank who underwent coronary angiography. CKD (n = 1,073) was defined as estimated glomerular filtration rate <60 ml/min/1.73 m2 or urine albumin/creatinine ratio >30 mg/g at baseline. Cox regression was used to compute hazard ratios (HR) for the association between hs-TnI levels (per doubling of hs-TnI: log2[hs-TnI] + 1) and death, cardiovascular death, and major adverse cardiac events (MACE), separately. Hs-TnI was a stronger predictor of death (CKD: HR 1.23, 95% confidence interval [CI] 1.15 to 1.31; no CKD: HR 1.11, 95% CI 1.05 to 1.17, p-interaction = 0.023), cardiovascular death (CKD: HR 1.24, 95% CI 1.14 to 1.34; no CKD: HR 1.15, 95% CI 1.07 to 1.22, p-interaction = 0.12), and MACE (CKD: HR 1.18, 95% CI 1.11 to 1.25; no CKD: HR 1.11, 95% CI 1.06 to 1.16, p-interaction = 0.095) in CKD compared with non-CKD. The association between hs-TnI and death in patients with CKD was stronger for patients without obstructive coronary artery disease (no obstructive coronary artery disease: HR 1.60, 95% CI 1.27 to 2.01; obstructive coronary artery disease: HR 1.19, 95% CI 1.11 to 1.27, p-interaction = 0.041). In conclusion, hs-TnI is a stronger predictor of adverse cardiovascular events in patients who have CKD than those without, even in the absence of obstructive coronary artery disease. Hs-TnI may identify CKD patients who are high risk for adverse cardiovascular outcomes in whom aggressive risk factor modification strategies are warranted.

CENTRAL OBESITY PREDICTS CIRCULATING PROGENITOR CELL LEVELS

Background: Obesity is a pro-inflammatory state leading to endothelial cell injury and dysfunction. In particular, central (android) obesity is associated with increased cardiovascular disease risk. Bone marrow derived CD34+ progenitor cells (PC) levels are elevated in patients with high body mass

ASSOCIATION BETWEEN CIRCULATING PROGENITOR CELLS AND OUTCOMES IN PATIENTS WITH CORONARY ARTERY DISEASE

Background: Circulating hematopoietic enriched progenitor cells (PCs) predict adverse cardiovascular outcomes in patients with coronary artery disease (CAD). The additive predictive role of endothelial enriched PCs expressing vascular endothelial growth factor receptor (VEGF) remains controversial.