Michael Mullen

Prospective Study of Heart Rate Variability and Mortality in Chronic Heart Failure Results of the United Kingdom Heart Failure Evaluation and Assessment of Risk Trial (UK-Heart)

BACKGROUND Patients with chronic heart failure (CHF) have a continuing high mortality. Autonomic dysfunction may play an important role in the pathophysiology of cardiac death in CHF. UK-HEART examined the value of heart rate variability (HRV) measures as independent predictors of death in CHF. METHODS AND RESULTS In a prospective study powered for mortality, we recruited 433 outpatients 62+/-9.6 years old with CHF (NYHA functional class I to III; mean ejection fraction, 0.41+/-0.17). Time-domain HRV indices and conventional prognostic indicators were related to death by multivariate analysis. During 482+/-161 days of follow-up, cardiothoracic ratio, SDNN, left ventricular end-systolic diameter, and serum sodium were significant predictors of all-cause mortality. The risk ratio for a 41.2-ms decrease in SDNN was 1.62 (95% CI, 1.16 to 2.44). The annual mortality rate for the study population in SDNN subgroups was 5.5% for >100 ms, 12.7% for 50 to 100 ms, and 51.4% for <50 ms. SDNN, creatinine, and serum sodium were related to progressive heart failure death. Cardiothoracic ratio, left ventricular end-diastolic diameter, the presence of nonsustained ventricular tachycardia, and serum potassium were related to sudden cardiac death. A reduction in SDNN was the most powerful predictor of the risk of death due to progressive heart failure. CONCLUSIONS CHF is associated with autonomic dysfunction, which can be quantified by measuring HRV. A reduction in SDNN identifies patients at high risk of death and is a better predictor of death due to progressive heart failure than other conventional clinical measurements. High-risk subgroups identified by this measurement are candidates for additional therapy after prescription of an ACE inhibitor.

Long-term outcomes after transcatheter aortic valve implantation in high-risk patients with severe aortic stenosis: the U.K. TAVI (United Kingdom Transcatheter Aortic Valve Implantation) Registry.

OBJECTIVES The objective was to define the characteristics of a real-world patient population treated with transcatheter aortic valve implantation (TAVI), regardless of technology or access route, and to evaluate their clinical outcome over the mid to long term. BACKGROUND Although a substantial body of data exists in relation to early clinical outcomes after TAVI, there are few data on outcomes beyond 1 year in any notable number of patients. METHODS The U.K. TAVI (United Kingdom Transcatheter Aortic Valve Implantation) Registry was established to report outcomes of all TAVI procedures performed within the United Kingdom. Data were collected prospectively on 870 patients undergoing 877 TAVI procedures up until December 31, 2009. Mortality tracking was achieved in 100% of patients with mortality status reported as of December 2010. RESULTS Survival at 30 days was 92.9%, and it was 78.6% and 73.7% at 1 year and 2 years, respectively. There was a marked attrition in survival between 30 days and 1 year. In a univariate model, survival was significantly adversely affected by renal dysfunction, the presence of coronary artery disease, and a nontransfemoral approach; whereas left ventricular function (ejection fraction <30%), the presence of moderate/severe aortic regurgitation, and chronic obstructive pulmonary disease remained the only independent predictors of mortality in the multivariate model. CONCLUSIONS Midterm to long-term survival after TAVI was encouraging in this high-risk patient population, although a substantial proportion of patients died within the first year.

Exercise intolerance in adult congenital heart disease: comparative severity, correlates, and prognostic implication.

Background—Although some patients with adult congenital heart disease (ACHD) report limitations in exercise capacity, we hypothesized that depressed exercise capacity may be more widespread than superficially evident during clinical consultation and could be a means of assessing risk. Methods and Results—Cardiopulmonary exercise testing was performed in 335 consecutive ACHD patients (age, 33±13 years), 40 non–congenital heart failure patients (age, 58±15 years), and 11 young (age, 29±5 years) and 12 older (age, 59±9 years) healthy subjects. Peak oxygen consumption (peak &OV0312;o2) was reduced in ACHD patients compared with healthy subjects of similar age (21.7±8.5 versus 45.1±8.6; P<0.001). No significant difference in peak &OV0312;o2 was found between ACHD and heart failure patients of corresponding NYHA class (P=NS for each NYHA class). Within ACHD subgroups, peak &OV0312;o2 gradually declined from aortic coarctation (28.7±10.4) to Eisenmenger (11.5±3.6) patients (P<0.001). Multivariable correlates of peak &OV0312;o2 were peak heart rate (r=0.33), forced expiratory volume (r=0.33), pulmonary hypertension (r=−0.26), gender (r=−0.23), and body mass index (r=−0.19). After a median follow-up of 10 months, 62 patients (18.5%) were hospitalized or had died. On multivariable Cox analysis, peak &OV0312;o2 predicted hospitalization or death (hazard ratio, 0.937; P=0.01) and was related to the frequency and duration of hospitalization (P=0.01 for each). Conclusions—Exercise capacity is depressed in ACHD patients (even in allegedly asymptomatic patients) on a par with chronic heart failure subjects. Lack of heart rate response to exercise, pulmonary arterial hypertension, and impaired pulmonary function are important correlates of exercise capacity, as is underlying cardiac anatomy. Poor exercise capacity identifies ACHD patients at risk for hospitalization or death.

Acute Systemic Inflammation Impairs Endothelium-Dependent Dilatation in Humans

BackgroundWe tested the hypothesis that endothelial dysfunction underlies the association between an acute inflammatory episode and the transiently increased risk of a cardiovascular event by examining the effects of an experimental inflammatory stimulus on endothelium-dependent vasodilation. Methods and ResultsSalmonella typhi vaccine was used to generate a systemic inflammatory response in healthy volunteers. In 12 subjects, dilatation of the brachial artery to flow and to sublingual nitroglycerin (NTG) was recorded (conduit vessel response), and in 6 subjects, venous occlusion plethysmography was used to measure forearm blood flow during intrabrachial infusion of the endothelium-dependent dilators acetylcholine (ACh) and bradykinin (BK) and the endothelium-independent dilators NTG and verapamil (resistance vessel response). Responses were assessed 16 hours before and 8 and 32 hours after vaccination. Vaccination resulted in elevations in white cell count and serum levels of interleukin-6 and interleukin-1 receptor antagonist. Eight hours after vaccination, resistance vessel responses to BK (P =0.0099) and ACh (P =0.0414) were markedly attenuated, and brachial artery flow-mediated dilatation was depressed. Resistance vessel responses to verapamil and NTG were unchanged, as was the conduit vessel response to NTG. Thirty-two hours after vaccination, resistance vessel responses to BK and ACh had returned to normal. ConclusionsS typhi vaccine generates a mild inflammatory reaction associated with temporary but profound dysfunction of the arterial endothelium in both resistance and conduit vessels to both physical and pharmacological dilator stimuli. This finding might explain the association between infection and inflammation and the enhanced risk of an acute cardiovascular event.

Mental Stress Induces Transient Endothelial Dysfunction in Humans

BackgroundMental stress has been linked to increased morbidity and mortality in coronary artery disease and to atherosclerosis progression. Experimental studies have suggested that damage to the endothelium may be an important mechanism. Methods and ResultsEndothelial function was studied in 10 healthy men (aged 50.4±9.6 years) and in 8 non–insulin-dependent diabetic men (aged 52.0±7.2 years). Brachial artery flow-mediated dilation (FMD, endothelium dependent) and response to 50 &mgr;g of sublingual glyceryl trinitrate (GTN, endothelium independent) were measured noninvasively by use of high-resolution ultrasound before and after (30, 90, and 240 minutes) a standardized mental stress test. The same protocol without mental stress was repeated on a separate occasion in the healthy men. In healthy subjects, FMD (5.0±2.1%) was significantly (P <0.01) reduced at 30 and 90 minutes after mental stress (2.8±2.3% and 2.3±2.4%, respectively) and returned toward normal after 4 hours (4.1±2.0%). Mental stress had no effect on the response to GTN. In the repeated studies without mental stress, FMD did not change. The diabetic subjects had lower FMD than did the control subjects (3.0±1.5% versus 5.0±2.1%, respectively;P =0.02) but showed no changes in FMD (2.7±1.1% after 30 minutes, 2.8±1.9% after 90 minutes, and 3.1±2.3% after 240 minutes) or GTN responses after mental stress. ConclusionsThese findings suggest that brief episodes of mental stress, similar to those encountered in everyday life, may cause transient (up to 4 hours) endothelial dysfunction in healthy young individuals. This might represent a mechanistic link between mental stress and atherogenesis.

Migraine Intervention With STARFlex Technology (MIST) Trial A Prospective, Multicenter, Double-Blind, Sham-Controlled Trial to Evaluate the Effectiveness of Patent Foramen Ovale Closure With STARFlex Septal Repair Implant to Resolve Refractory Migraine Headache

Background— Patent foramen ovale (PFO) is prevalent in patients with migraine with aura. Observational studies show that PFO closure resulted in migraine cessation or improvement in ≈80% of such patients. We investigated the effects of PFO closure for migraine in a randomized, double-blind, sham-controlled trial. Methods and Results— Patients who suffered from migraine with aura, experienced frequent migraine attacks, had previously failed ≥2 classes of prophylactic treatments, and had moderate or large right-to-left shunts consistent with the presence of a PFO were randomized to transcatheter PFO closure with the STARFlex implant or to a sham procedure. Patients were followed up for 6 months. The primary efficacy end point was cessation of migraine headache 91 to 180 days after the procedure. In total, 163 of 432 patients (38%) had right-to-left shunts consistent with a moderate or large PFO. One hundred forty-seven patients were randomized. No significant difference was observed in the primary end point of migraine headache cessation between implant and sham groups (3 of 74 versus 3 of 73, respectively; P=0.51). Secondary end points also were not achieved. On exploratory analysis, excluding 2 outliers, the implant group demonstrated a greater reduction in total migraine headache days (P=0.027). As expected, the implant arm experienced more procedural serious adverse events. All events were transient. Conclusions— This trial confirmed the high prevalence of right-to-left shunts in patients with migraine with aura. Although no significant effect was found for primary or secondary end points, the exploratory analysis supports further investigation. The robust design of this study has served as the model for larger trials that are currently underway in the United States and Europe.

Exercise training enhances endothelial function in young men

OBJECTIVES The present study was designed to assess whether exercise training can enhance endothelium-dependent dilatation in healthy young men. BACKGROUND Exercise has been shown to reduce cardiovascular morbidity and mortality, but the mechanisms for this benefit are unclear. Endothelial dysfunction is an early event in atherogenesis, and animal studies have shown that exercise training can enhance endothelial function. METHODS We have examined the effect of a standardized, 10-week, aerobic and anaerobic exercise training program on arterial physiology in 25 healthy male military recruits, aged 17 to 24 (mean 20) years, of average fitness levels. Each subject was studied before starting, and after completing the exercise program. Baseline vascular reactivity was compared with that of 20 matched civilian controls. At each visit, the diameter of the right brachial artery was measured at rest, during reactive hyperemia (increased flow causing endothelium-dependent dilation) and after sublingual glyceryltrinitrate (GTN; an endothelium-independent dilator), using high-resolution external vascular ultrasound. RESULTS At baseline, flow-mediated dilatation (FMD) and GTN-mediated dilatation were similar in the exercise and control groups (FMD 2.2+/-2.4% and 2.4+/-2.8%, respectively, p = 0.33; GTN 13.4+/-6.2 vs. 16.7+/-5.9, respectively, p = 0.53). In the military recruits, FMD improved from 2.2+/-2.4% to 3.9+/-2.5% (p = 0.01), with no change in the GTN-mediated dilation (13.4+/-6.2% vs. 13.9+/-5.8%, p = 0.31) following the exercise program. CONCLUSION Exercise training enhances endothelium-dependent dilation in young men of average fitness. This may contribute to the benefit of regular exercise in preventing cardiovascular disease.

Heterogenous Nature of Flow-Mediated Dilatation in Human Conduit Arteries In Vivo: Relevance to Endothelial Dysfunction in Hypercholesterolemia

Abstract — Flow-mediated dilatation (FMD) of conduit arteries is dependent on an intact endothelium, although the mechanisms are not fully understood. Using high-resolution ultrasound, we examined the role of endothelial mediators in radial artery dilatation in response to transient (short period of reactive hyperemia) and sustained (prolonged period of reactive hyperemia, hand warming, or an incremental infusion of acetylcholine into the distal radial artery) hyperemia. After short episodes of reactive hyperemia, FMD was abolished by local infusion of the nitric oxide synthesis inhibitor NGmonomethyl-l-arginine (5.3±1.2% versus 0.7±0.7%, P <0.001). In contrast, basal vessel diameter and dilatation after prolonged episodes of reactive hyperemia, hand warming, and distal infusion of acetylcholine were not attenuated by nitric oxide synthesis inhibition. Inhibition of cyclooxygenase or local autonomic nervous system blockade also had no effect on FMD. Patients with hypercholesterolemia exhibited reduced FMD in response to transient hyperemia, but the response to sustained hyperemia was normal. These data suggest heterogeneity of endothelial responses to blood flow that are dependent on the characteristics of the flow stimulus. Dilatation after brief episodes of hyperemia is mediated by release of nitric oxide, whereas dilatation during sustained hyperemia is unaffected by NO synthesis inhibition. Hypercholesterolemia seems to differentially affect these pathways with impairment of the nitric oxide–dependent pathway and preservation of non nitric oxide–mediated dilatation to sustained flow stimuli.

Ischemic Preconditioning Prevents Endothelial Injury and Systemic Neutrophil Activation During Ischemia-Reperfusion in Humans In Vivo

BACKGROUND Endothelial dysfunction leading to neutrophil infiltration of tissues has been implicated in tissue injury caused by ischemia-reperfusion (IR). Tissue injury during IR can be reduced by prior ischemic preconditioning (IPC). In humans, it is unclear whether endothelial dysfunction occurs during IR or whether IPC offers protection against endothelial dysfunction and inflammatory cell activation. We studied the effects of experimental IR on endothelial and neutrophil function in the human forearm in vivo and examined the protection afforded by IPC. METHOD AND RESULTS The forearm was made ischemic for 20 minutes by inflating a blood pressure cuff to 200 mm Hg. We assessed endothelial function of conduit (radial artery flow-mediated dilation) and resistance vessels (blood flow responses to intra-arterial infusion of the endothelium-dependent dilator acetylcholine) in healthy volunteers before and after IR. IR reduced flow-mediated dilation of the radial artery at 15 minutes of reperfusion (7.7+/-1.5% to 3.5+/-0.9%) and the dilator response of resistance vessels to acetylcholine at 15, 30, and 60 minutes of reperfusion. IR did not reduce the dilator response of the radial artery to glyceryltrinitrate and only caused a small reduction of glyceryltrinitrate-induced dilation of resistance vessels at 60 minutes of reperfusion. IR caused an increase in neutrophil CD11b expression and platelet-neutrophil complexes in the circulating blood. IPC (three 5-minute episodes of ischemia) before IR prevented endothelial dysfunction and neutrophil activation. CONCLUSIONS A clinically relevant period of ischemia-reperfusion causes profound and sustained endothelial dysfunction and systemic neutrophil activation. IPC attenuates both of these effects in humans.

2-Year Follow-Up of Patients Undergoing Transcatheter Aortic Valve Implantation Using a Self-Expanding Valve Prosthesis

OBJECTIVES The purpose of this study was to evaluate the safety, device performance, and clinical outcome up to 2 years for patients undergoing transcatheter aortic valve implantation (TAVI). BACKGROUND The role of TAVI in the treatment of calcific aortic stenosis evolves rapidly, but mid- and long-term results are scarce. METHODS We conducted a prospective, multicenter, single-arm study with symptomatic patients undergoing TAVI for treatment of severe aortic valve stenosis using the 18-F Medtronic CoreValve (Medtronic, Minneapolis, Minnesota) prosthesis. RESULTS In all, 126 patients (mean age 82 years, 42.9% male, mean logistic European System for Cardiac Operative Risk Evaluation score 23.4%) with severe aortic valve stenosis (mean gradient 46.8 mm Hg) underwent the TAVI procedure. Access was transfemoral in all but 2 cases with subclavian access. Retrospective risk stratification classified 54 patients as moderate surgical risk, 51 patients as high-risk operable, and 21 patients as high-risk inoperable. The overall technical success rate was 83.1%. Thirty-day all-cause mortality was 15.2%, without significant differences in the subgroups. At 2 years, all-cause mortality was 38.1%, with a significant difference between the moderate-risk group and the combined high-risk groups (27.8% vs. 45.8%, p = 0.04). This difference was mainly attributable to an increased risk of noncardiac mortality among patients constituting the high-risk groups. Hemodynamic results remained unchanged during follow-up (mean gradient: 8.5 ± 2.5 mm Hg at 30 days and 9.0 ± 3.4 mm Hg at 2 years). Functional class improved in 80% of patients and remained stable over time. There was no incidence of structural valve deterioration. CONCLUSIONS The TAVI procedure provides sustained clinical and hemodynamic benefits for as long as 2 years for patients with symptomatic severe aortic stenosis at increased risk for surgery.