Sex-Specific Response to Cardiac Resynchronization Therapy: Effect of Left Ventricular Size and QRS Duration in Left Bundle Branch Block.

OBJECTIVES: In this study, the authors sought to assess the impact of body and heart size on sex-specific cardiac resynchronization therapy (CRT) response rate, according to QRS duration (QRSd) as a continuum. BACKGROUND: Effects of CRT differ between sexes for any given QRSd. METHODS: New York Heart Association functional class III/IV patients with nonischemic cardiomyopathy and "true" left bundle branch block (LBBB) were evaluated. Left ventricular mass (LVM) and end-diastolic volume were measured echocardiographically. Positive response was defined by left ventricular ejection fraction (LVEF) improvement post-CRT. RESULTS: Among 130 patients (LVEF 19 ± 7.1%; QRSd 165 ± 20 ms; 55% female), CRT improved LVEF to 32 ± 14% (p < 0.001) during a median 2 years follow-up. Positive responses occurred in 103 of 130 (79%) (78% when QRSd <150 ms vs. 80% when QRSd ≥150 ms; p = 0.8). Body surface area (BSA), QRSd, and LVM were lower in women, but QRSd/LVM ratio greater (p < 0.0001). Sexes did not differ for pharmacotherapy and comorbidities, but female CRT response was greater: 90% (65 of 72) versus 66% (38 of 58) in males (p < 0.001). With QRSd as a continuum, the overall CRT-response relationship showed a progressive increase to plateau between 150 and 170 ms, then a decrease. Sex-specific differences were conspicuous: among females, a peak effect was observed between 135 and 150 ms, thereafter a decline, with the male response rate lower, but with a gradual increase as QRSd lengthened. Sex-specific differences were unaltered by BSA, but resolved with integration of LVM or end-diastolic volume. CONCLUSIONS: Sex differences in the QRSd-response relationship among CRT patients with LBBB were unexplained by application of strict LBBB criteria or by BSA, but resolved by QRSd normalization for heart size using LV mass or volume.

Ablation for Persistent Atrial Fibrillation-Is There a Role for More Than PVI?

OPINION STATEMENT: Persistent atrial fibrillation (AF) is a prevalent condition that can be difficult to treat medically, and an ablation strategy is often sought. Currently, the cornerstone of AF ablation strategies is pulmonary vein isolation (PVI). Unfortunately, the single procedure success rates are limited, particularly when long-term outcomes (>1 year) are considered. As a result, the most recent consensus statement recommends that in patients with persistent AF a more extensive ablation be considered. Many additive procedural approaches to PVI have been investigated. These include electrical compartmentalization of the atria with linear lesions (LLs), ablation of complex fractionated atrial electrograms (CFAEs), ablation of the dominant frequency (DF) signals, and focal impulse and rotor modulation (FIRM) ablation. Each of these approaches has demonstrated degrees of additive success when performed with a PVI in patients with persistent AF. This review provides an in-depth discussion of these techniques, their successes in treating persistent AF, and their shortcomings.

Prevalence and prediction of obstructive coronary artery disease in patients referred for valvular heart surgery.

Current guidelines recommend a coronary evaluation before valvular heart surgery (VHS). Diagnostic coronary angiography is recommended in patients with known coronary artery disease (CAD) and those with high pretest probability of CAD. In patients with low or intermediate pretest probability of CAD, the guidelines recommend coronary computed tomographic angiography. However, there are no tools available to objectively assess a patient's risk for obstructive CAD before VHS. To address this deficit, 5,360 patients without histories of CAD who underwent diagnostic coronary angiography as part of preoperative evaluation for VHS were identified. Obstructive CAD was defined as ≥50% stenosis in ≥1 artery. Of the patients assessed, 1,035 (19.3%) were found to have obstructive CAD. Through multivariate analysis, age, gender, diabetes, renal dysfunction, hyperlipidemia, and a family history of premature CAD were found to be associated with the presence of obstructive CAD (p <0.001 for all). After adjustment, the specific dysfunctional valve was not associated with the presence of obstructive CAD. Patients were then randomly split into derivation and validation cohorts. Within the derivation cohort, using only age, gender, and the presence or absence of risk factors, a model was constructed to predict the risk for obstructive CAD (C statistic 0.766, 95% confidence interval 0.750 to 0.783). The risk prediction model performed well within the validation cohort (C statistic 0.767, 95% confidence interval 0.751 to 0.784, optimism 0.004). The bias-corrected C statistic for the model was 0.765 (95% confidence interval 0.748 to 0.782). In conclusion, this novel risk prediction tool can be used to objectively risk-stratify patients who undergo preoperative evaluation before VHS and to facilitate appropriate triage to computed tomographic angiography or diagnostic coronary angiography.

miRNA-548c: a specific signature in circulating PBMCs from dilated cardiomyopathy patients.

High fidelity genome-wide expression analysis has strengthened the idea that microRNA (miRNA) signatures in peripheral blood mononuclear cells (PBMCs) can be potentially used to predict the pathology when anatomical samples are inaccessible like the heart. PBMCs from 48 non-failing controls and 44 patients with relatively stable chronic heart failure (ejection fraction of ≤ 40%) associated with dilated cardiomyopathy (DCM) were used for miRNA analysis. Genome-wide miRNA-microarray on PBMCs from chronic heart failure patients identified miRNA signature uniquely characterized by the downregulation of miRNA-548 family members. We have also independently validated downregulation of miRNA-548 family members (miRNA-548c & 548i) using real time-PCR in a large cohort of independent patient samples. Independent in silico Ingenuity Pathway Analysis (IPA) of miRNA-548 targets shows unique enrichment of signaling molecules and pathways associated with cardiovascular disease and hypertrophy. Consistent with specificity of miRNA changes with pathology, PBMCs from breast cancer patients showed no alterations in miRNA-548c expression compared to healthy controls. These studies suggest that miRNA-548 family signature in PBMCs can therefore be used to detect early heart failure. Our studies show that cognate networking of predicted miRNA-548 targets in heart failure can be used as a powerful ancillary tool to predict the ongoing pathology.

Cellular proliferative response to cardiac troponin-I in patients with idiopathic dilated cardiomyopathy.

BACKGROUND: Approximately 20% of patients with idiopathic dilated cardiomyopathy (iDCM) have autoantibodies (AAbs) specific to cardiac troponin-I (cTnI). However, there has been no work evaluating active cellular autoimmunity. We aimed to identify a cTnI-stimulated cellular autoimmune response and to correlate our findings with cTnI AAb production. METHODS: Samples were obtained from stable ambulatory iDCM patients and healthy controls. Peripheral blood monocytes were incubated with cTnI, and cellular proliferation was measured using flow cytometry. AAbs against cTnI were detected by enzyme-linked immunosorbent assay. RESULTS: A positive cellular proliferative response to cTnI was identified in 20.5% (9/44) patients with iDCM and 5.7% (2/35) of healthy controls (p < 0.05). Positive cTnI AAbs were identified in 20% (7/35) of healthy controls and 13.6% (6/44) of patients with iDCM (p = NS). The presence of cTnI AAbs did not correlate with a positive cellular proliferative response. However, patients with iDCM who had an AAb response to cTnI were less likely to be taking a statin (p < 0.05). CONCLUSIONS: A cellular autoimmune response to cTnI is demonstrated in a subset of patients with iDCM. However, the presence of a cellular response did not correlate with the presence of AAbs to the same antigen.

Red cell distribution width, C-reactive protein, the complete blood count, and mortality in patients with coronary disease and a normal comparison population.

BACKGROUND: Red cell distribution width (RDW) is associated with morbidity and mortality in coronary artery disease (CAD), but the connection of RDW with chronic inflammation is equivocal. METHODS: In 1,489 patients with CAD and 8.4-15.2 years of follow-up all-cause mortality and RDW were studied using Cox regression. RDW and its associations with inflammation, liver function, renal function, and body mass were assessed. A population of 449 normal (No-CAD) patients also was evaluated. RESULTS: RDW predicted all-cause mortality in a step-wise manner (HR=1.37 per quintile; 95% CI=1.29, 1.46; p-trend<0.001). A significant but meaningless correlation between RDW and high-sensitivity C-reactive protein (hsCRP) was identified (r=0.181; p<0.001). With full adjustment, RDW remained significant (p-trend<0.001) and the strongest predictor of mortality among all factors included in the model. RDW also strongly predicted all-cause mortality in the normal control population (HR=1.33 per quintile, CI=1.15, 1.55; p-trend<0.001), but hsCRP did not predict mortality among normal controls. CONCLUSIONS: RDW was associated with mortality in patients with CAD and may provide clinically useful prognostication. Although RDW was correlated with hsCRP, they were independent predictors of mortality. RDW has been incorporated into risk prediction tool using data from basic chemistries available at: http://intermountainhealthcare.org/IMRS.

Antiinflammatory autoimmune cellular responses to cardiac troponin I in idiopathic dilated cardiomyopathy.

BACKGROUND: Autoimmune mechanisms, particularly through generation of autoantibodies, may contribute to the pathophysiology of idiopathic dilated cardiomyopathy (iDCM). The precise role of cellular autoimmune responses to cardiac-specific antigens has not been well described in humans. The purpose of this study was to characterize the cellular autoimmune response to cardiac troponin I (cTnI), specifically, the release of cytokines by peripheral blood mononuclear cells (PBMCs), in subjects with iDCM and healthy control subjects. METHODS AND RESULTS: We performed enzyme-linked immunospot assays on PBMCs isolated from subjects with iDCM and healthy control subjects to examine the ex vivo interferon-gamma (IFN-γ) and interleukin-10 (IL-10) production in response to cTnI exposure. Thirty-five consecutive subjects with iDCM (mean age 53 ± 11 years, 60% male, left ventricular ejection fraction 23 ± 7%) and 26 control subjects (mean age 46 ± 13 years, 46% male) were prospectively enrolled. IFN-γ production in response to cTnI did not differ between the groups (number of secreting cells 26 ± 49 vs 38 ± 53, respectively; P = .1). In contrast, subjects with iDCM showed significantly higher IL-10 responses to cTnI compared with control subjects (number of secreting cells 386 ± 428 vs 152 ± 162, respectively; P < .05). Among iDCM subjects, heightened IL-10 response to cTnI was associated with reduced systemic inflammation and lower prevalence of advanced diastolic dysfunction compared with those with normal IL-10 response to cTnI. CONCLUSIONS: Our preliminary findings suggest that a heightened cellular autoimmune IL-10 response to cTnI is detectable in a subset of patients with iDCM, which may be associated with reduced systemic levels of high-sensitivity C-reactive protein and lower prevalence of advanced diastolic dysfunction.

Recent insights into the role of autoimmunity in idiopathic dilated cardiomyopathy.

Dilated cardiomyopathy is a devastating disease associated with poor outcomes. Although the etiology of this disease remains largely unknown, so-called "idiopathic" dilated cardiomyopathy (iDCM) is associated with evidence of an autoimmune process that may be contributing to the pathophysiology of this disease. Indeed, iDCM shares many characteristics with other autoimmune diseases, including an association with systemic and organ-specific inflammation, an association with viral infections, a genetic predisposition, and a correlation with specific human leukocyte antigen subtypes. Additionally, numerous pathologic cardiac-specific autoantibodies have been associated with iDCM, including those against alpha-myosin, the beta(1)-adrenoceptor, and cardiac troponin I. This review highlights the emerging evidence regarding autoimmune characteristics of iDCM, and summarizes the data of specific immunomodulatory therapies used to target autoimmune mechanisms in the treatment of patients with this devastating disease.

Soluble CD40 ligand as a predictor of coronary artery disease and long-term clinical outcomes in stable patients undergoing coronary angiography.

BACKGROUND: In patients with acute coronary syndrome (ACS), elevated levels of soluble CD40 ligand (sCD40L) are associated with increased risk of cardiovascular events. We evaluated sCD40L levels and future cardiovascular events in patients not experiencing ACS. METHODS: Serum sCD40L levels were measured in 909 patients undergoing angiography. A three-way matching scheme (age, gender and catheterization time period) identified 303 patients with coronary artery disease (CAD) who experienced a cardiac event within 1 year (CAD/event), 303 patients with CAD free of events (CAD/no event) and 303 patients without CAD and free of events (no CAD). RESULTS: Average age was 64 +/- 11 years; 74% were males. Median (+/- SE) sCD40L levels were higher for no CAD patients (335 +/- 60 pg/ml) compared to CAD (248 +/- 65 pg/ml, p = 0.01) and to CAD/event (233 +/- 63 pg/ml, p < 0.001). There was no significant difference in median sCD40L levels between CAD/no event and CAD/event patients. Higher sCD40L quartiles were associated with a significant decrease in the risk of CAD/event versus no CAD (quartile 4 versus quartile 1: odds ratio = 0.59, p = 0.03). There was a nonsignificant trend towards a decreased risk of CAD as compared to no CAD, and for CAD/event versus CAD. CONCLUSIONS: In non-ACS patients, higher sCD40L levels were associated with a decreased risk of CAD. This novel interaction of sCD40L raises interesting questions for CAD pathogenesis.

Reaction progress of chromophore biogenesis in green fluorescent protein.

The mature form of green fluorescent protein (GFP) is generated by a spontaneous self-modification process that is essentially irreversible. A key step in chromophore biosynthesis involves slow air oxidation of an intermediate species, in which the backbone atoms of residues 65-67 have condensed to form a five-membered heterocycle. We have investigated the kinetics of hydrogen peroxide evolution during in vitro GFP maturation and found that the H2O2 coproduct is generated prior to the acquisition of green fluorescence at a stoichiometry of 1:1 (peroxide/chromophore). The experimental progress curves were computer-fitted to a three-step mechanism, in which the first step proceeds with a time constant of 1.5 (+/-1.1) min and includes protein folding and peptide cyclization. Kinetic data obtained by HPLC analysis support a rapid cyclization reaction that can be reversed upon acid denaturation. The second step proceeds with a time constant of 34.0 (+/-1.5) min and entails rate-limiting protein oxidation, as supported by a mass loss of 2 Da observed for tryptic peptides derived from species that accumulate during the reaction. The final step in GFP maturation proceeds with a time constant of 10.6 (+/-1.2) min, suggesting that this step may contribute to overall rate retardation. We propose that under highly aerobic conditions, the dominant reaction path follows a cyclization-oxidation-dehydration mechanism, in which dehydration of the heterocycle is facilitated by slow proton abstraction from the Tyr66 beta-carbon. In combination, the results presented here suggest a role for molecular oxygen in trapping the cyclized form of GFP.

Base catalysis of chromophore formation in Arg96 and Glu222 variants of green fluorescent protein.

In green fluorescent protein (GFP), chromophore biosynthesis is initiated by a spontaneous main-chain condensation reaction. Nucleophilic addition of the Gly67 amide nitrogen to the Ser65 carbonyl carbon is catalyzed by the protein fold and leads to a heterocyclic intermediate. To investigate this mechanism, we substituted the highly conserved residues Arg96 and Glu222 in enhanced GFP (EGFP). In the R96M variant, the rate of chromophore formation is greatly reduced (time constant = 7.5 x 10(3) h, pH 7) and exhibits pH dependence. In the E222Q variant, the rate is also attenuated at physiological pH (32 h, pH 7) but is accelerated severalfold beyond that of EGFP at pH 9-10. In contrast, EGFP maturation is pH-independent and proceeds with a time constant of 1 h (pH 7-10). Mass spectrometric results for R96M and E222Q indicate accumulation of the pre-cyclization state, consistent with rate-limiting backbone condensation. The pH-rate profile implies that the Glu222 carboxylate titrates with an apparent pK(a) of 6.5 in R96M and that the Gly67 amide nitrogen titrates with an apparent pK(a) of 9.2 in E222Q. These data suggest a model for GFP chromophore synthesis in which the carboxylate of Glu222 plays the role of a general base, facilitating proton abstraction from the Gly67 amide nitrogen or the Tyr66 alpha-carbon. Arg96 fulfills the role of an electrophile by lowering the respective pK values and stabilizing the alpha-enolate. Modulating the base strength of the proton-abstracting group may aid in the design of fast-maturing GFPs with improved characteristics for real-time monitoring of cellular events.

Serum uric acid independently predicts mortality in patients with significant, angiographically defined coronary disease.

BACKGROUND: Uric acid is a nontraditional risk factor implicated in the development of coronary artery disease (CAD). This study prospectively evaluated the predictive value of serum uric acid (SUA) levels for mortality after angiographic diagnosis of CAD. METHODS: Blood samples were collected from 1,595 consecutive, consenting patients with significant, angiographically defined CAD (stenosis 70%). Baseline and procedural variables were recorded and levels of SUA were measured. Patients were followed to death or to the time of contact (mean 2.6 years, range 1.8-5.0 years). RESULTS: Patients averaged 65 +/- 11 years of age, 78% were male and 170 subjects died during the follow-up period. In univariate analysis of prospectively defined quintiles, SUA predicted all-cause mortality (fifth quintile vs. first four quintiles: hazard ratio 1.9, p < 0.001). In multivariable Cox regression controlling for 20 covariables, independent predictive value for mortality was retained by SUA (hazard ratio 1.5, confidence interval 1.02-2.1, p = 0.04). In subgroup analysis based on diuretic use status, SUA independently predicted mortality among patients not using diuretics, while SUA was not a significant predictor of mortality among those who used diuretics. CONCLUSIONS: In patients with significant, angiographically defined CAD, SUA predicted mortality independent of traditional risk factors. This suggests that elevated SUA may be a risk factor for mortality in patients with significant cardiovascular disease and may be a stronger secondary than primary risk factor in CAD.

A theoretical investigation of charge transfer in several substituted acridinium ions.

We present calculations for various properties of the ground and excited states of several arylamine-substituted acridinium ion systems that have been studied experimentally. Using ab initio and semiempirical quantum mechanical methods together with the generalized Mulliken-Hush (GMH) model, we examine the excitation energies, dipole moment shifts, and electronic coupling elements for the vertical charge shift (CSh) processes in these systems. We also examine solvent effects on these properties using a dielectric continuum reaction field model. The results are in generally good agreement with available experimental results and indicate that there is strong electronic coupling in these systems over a wide range of torsional angles. Nevetheless, the initial and final cationic states remain reasonably well-localized over this range, and thus TICT state formation is unlikely in these systems. Finally, a version of the GMH model based on Koopmans' Theorem is developed and found to yield coupling elements generally within a factor of 2 of the many-electron GMH for a sample acridinium system, but with overestimated adiabatic and diabatic dipole moment differences.

Improvements in 1-year cardiovascular clinical outcomes associated with a hospital-based discharge medication program.

BACKGROUND: Despite recent advances in the treatment and prevention of cardiovascular disease, a treatment gap for secondary prevention medications still exists. OBJECTIVE: To develop and implement a program ensuring appropriate prescription of aspirin, statins, beta-blockers, angiotensin-converting enzyme inhibitors, and warfarin at hospital discharge. DESIGN: A nonrandomized before-after study comparing patients hospitalized before (1996-1998) and after (1999-2002) implementation of a discharge medication program (DMP). Patients were followed for up to 1 year. SETTING: The 10 largest hospitals in the Utah-based Intermountain Health Care system. PATIENTS: In the pre-DMP and DMP time periods, 26,000 and 31,465 patients, respectively, were admitted to cardiovascular services (n = 57,465). MEASUREMENTS: Prescription of indicated medications at hospital discharge; postdischarge death or readmission. RESULTS: By 1 year, the rate of prescription of each medication increased significantly to more than 90% (P < 0.001); this rate was sustained. At 1 year, unadjusted absolute event rates for readmission and death, respectively, were 210 per 1000 person-years and 96 per 1000 person-years before DMP implementation and 191 per 1000 person-years and 70 per 1000 person-years afterward. Relative risk for death and readmission at 30 days decreased after DMP implementation; hazard ratios (HRs) for death and readmission were 0.81 (95% CI, 0.73 to 0.89) and 0.92 (CI, 0.87 to 0.99) (P < 0.001 and P = 0.017, respectively). At 1 year, risk for death continued to decrease (hazard ratio, 0.79 [CI, 0.75 to 0.84]; P < 0.001) while risk for readmission stabilized (hazard ratio, 0.94 [CI, 0.90 to 0.98]; P = 0.002), probably because survivors had more opportunities to be readmitted. LIMITATIONS: The study design was observational and nonrandomized, and the authors could not control for potential confounders or determine the extent to which secular trends accounted for the observed improvements. CONCLUSIONS: A relatively simple quality improvement program aimed at enhancing the prescription of appropriate discharge medications among cardiovascular patients is feasible and can be sustained within an integrated multihospital system. Such a program may be associated with improvements in cardiovascular readmission rates and mortality.

Nitric oxide inhibits the rate and strength of cardiac contractions in the lobster Homarus americanus by acting on the cardiac ganglion.

The lobster heart is synaptically driven by the cardiac ganglion, a spontaneously bursting neural network residing within the cardiac lumen. Here, we present evidence that nitric oxide (NO) plays an inhibitory role in lobster cardiac physiology. (1) NO decreases heartbeat frequency and amplitude. Decreased frequency is a direct consequence of a decreased ganglionic burst rate. Decreased amplitude is an indirect consequence of decreased burst frequency, attributable to the highly facilitating nature of the synapses between cardiac ganglion neurons and muscle fibers (although, during prolonged exposure to NO, amplitude recovers to the original level by a frequency-independent adaptation mechanism). NO does not alter burst duration, spikes per burst, heart muscle contractility, or amplitudes of synaptic potentials evoked by stimulating postganglionic motor nerves. Thus, NO acts on the ganglion, but not on heart muscle. (2) Two observations suggest that NO is produced within the lobster heart. First, immunoblot analysis shows that nitric oxide synthase (NOS) is strongly expressed in heart muscle relative to other muscles. Second, L-nitroarginine (L-NA), an NOS inhibitor, increases the rate of the heartbeat (opposite to the effects of NO). In contrast, the isolated ganglion is insensitive to L-NA, suggesting that heart muscle (but not the ganglion) produces endogenous NO. Basal heart rate varies from animal to animal, and L-NA has the greatest effect on the slowest hearts, presumably because these hearts are producing the most NO. Thus, because the musculature is a site of NOS expression, whereas the ganglion is the only intracardiac target of NO, we hypothesize that NO serves as an inhibitory retrograde transmitter.

Beta-blockers reduce the incidence of clinical restenosis: prospective study of 4840 patients undergoing percutaneous coronary revascularization.

BACKGROUND: Restenosis after percutaneous transluminal coronary intervention (PCI) remains a serious complication in the treatment of coronary artery disease. Although beta-adrenergic receptor blockers (BBs) effectively reduce many cardiac events, no large prospective studies have examined the association of BBs with restenosis. METHODS: We prospectively evaluated the association of BBs (prescribed at hospital discharge) with clinical restenosis in 4840 patients who underwent stent placement (60%), balloon angioplasty (32%), or rotational atherectomy (8%). Clinical restenosis was defined as repeat target lesion revascularization or coronary artery bypass grafting within 6 months of PCI. Other end points included 9-month clinical restenosis, repeat target lesion PCI (only), long-term (5-year) target lesion repeat-PCI, and major adverse cardiac events (MACE). Multivariable regression adjusted the effect of BBs on clinical restenosis for 15 covariables. RESULTS: The average patient age was 63 years, 75% were men, and 37% received a BB prescription. The incidence of clinical restenosis was 12% overall and was lower among those prescribed a BB (10.0% for BB, 13.5% for none, adjusted odds ratio [OR] 0.76, P =.004). Other predictors of decreased restenosis included stent use, age, and smoking; predictors of increased restenosis included diabetes, atherectomy, and number of treated vessels. BBs also reduced 9-month clinical restenosis (10.3% vs 13.5%, OR 0.75, P =.004), MACE (16.5% vs 20.9%, OR 0.75, P <.001), 6-month target lesion restenosis (7.8% vs 10.2%, OR 0.75, P =.006), and 5-year target lesion restenosis (12.0% vs 14.0%, OR 0.83, P =.046). CONCLUSIONS: beta-Adrenergic receptor blockers prescribed after PCI reduced the risk of clinical restenosis, target lesion restenosis, and MACE in this cohort of 4840 patients. The mechanism by which beta-blockers conferred a protective effect against restenosis remains to be determined.