Citations

Background —Increasingly, dobutamine stress echocardiography has been used for detection of coronary artery disease. Less information exists regarding the incremental prognostic value of the test, including semiquantitative wall scoring, compared with clinical and rest echocardiographic variables. Methods and Results —Follow-up information was obtained from 860 patients who underwent dobutamine stress echocardiography over a 2-year period. To determine the value of dobutamine stress echocardiography in predicting cardiac events, including cardiac death and myocardial infarction, clinical and rest and stress echocardiographic data were considered in a stepwise Cox multivariate regression model. During follow-up of up to 52 months, 72 patients underwent coronary revascularization before any cardiac event and were censored. Eighty-six patients had cardiac events, including nonfatal myocardial infarction in 36 and cardiac death in 50. In a multivariate model, a history of congestive heart failure, the percentage of abnormal segments at peak stress, and an abnormal left ventricular end-systolic volume response to stress were independent predictors of cardiac events. The model that best predicted subsequent cardiac events included clinical and stress echocardiographic data. Conclusions —Dobutamine stress echocardiography with semiquantitative segmental wall scoring provides important incremental information in predicting subsequent cardiac events.

Background —Approximately 360 000 Americans experience sudden cardiac arrest each year; current treatments are expensive and not very effective. Public access defibrillation (PAD) is a novel treatment for out-of-hospital sudden cardiac arrest that refers to use of automated external defibrillators by the lay public or by nonmedical personnel such as police. A clinical trial has been proposed to evaluate the effectiveness of public access defibrillation, but it is unclear whether such early defibrillation will offer sufficient value for money. Our objective was to estimate the potential cost-effectiveness of public access defibrillation by use of decision analysis. Methods and Results —A decision model compared the potential cost-effectiveness of standard emergency medical services (EMS) systems with that of EMS supplemented by PAD. We considered defibrillation by lay responders or police, using an analysis with a US health-care perspective. Input data were derived from published data or fiscal databases. Future costs and effects were discounted at 3%. Monte Carlo simulation was performed to estimate the variability in the costs and effects of each program. Sensitivity analyses assessed the robustness of the results to changes in input data. A standard EMS system had a median cost of $5900 per cardiac arrest patient (interquartile range, IQR, $3200 to $10 900) and yielded a median of 0.25 quality-adjusted life years (IQR, 0.20 to 0.30). PAD by lay responders had a median incremental cost of $44 000 per additional quality-adjusted life year (IQR, $29 000 to $68 900). PAD by police had a median incremental cost of $27 200 per additional quality-adjusted life year (IQR, $15 700 to $47 800). The results were sensitive to changes in the cost and relative survival benefit of PAD. Conclusions —Although more expensive than standard EMS for sudden cardiac arrest, PAD may be economically attractive. The effectiveness and cost-effectiveness of PAD should be assessed in a randomized, controlled trial.

Background Transesophageal echocardiography (TEE) is the diagnostic modality of choice for visualizing the left atrial appendage (LAA). This study defined the morphology of the LAA in normal autopsy specimen hearts and considered the implications of these findings for TEE studies. Methods and Results Five hundred normal autopsy hearts were reviewed (25 male and 25 female subjects from each decade for 10 decades). LAA length, width, orifice size, and number of lobes were recorded. Number of lobes was compared between sexes with the rank sum test and regressed against age. Mean length, width, and orifice size increased with age, up to age 20 years, in both sexes. Rates were significantly different between sexes for LAA size ( P =.011) and width ( P =.006). After age 20, statistically significant but clinically insignificant age-related changes were observed. Fifty-four percent of LAAs had two lobes (range, 1 to 4), with no age or sex differences. Lobes exist in different planes of the heart. Most pectinate muscles were ≥1 mm in width. Pectinate muscles <1 mm (2.6% of cases) were seen in only the first and last decades. Conclusions Age- and sex-related differences in LAA dimensions exist. These differences and the existence of multilobed appendages are important in the accurate TEE evaluation of LAA. Because lobes exist in different planes, imaging must be done in multiple planes to visualize the entire LAA.

Background This study was undertaken to test the hypothesis that β-adrenergic stimulation in the setting of membrane depolarization will potentiate flecainide-induced conduction slowing. Methods and Results To elucidate the potential mechanism for the flecainide proarrhythmia observed in CAST, the voltage dependence of β-adrenergic modulation of impulse propagation in eight flecainide-superfused canine Purkinje fibers was examined with a dual-microelectrode technique. At physiological membrane potentials (V m ) ([K + ] o =5.4 μmol), 1 μmol flecainide decreased V̇ max from 698±55 to 610±72 V/s ( P =.003) and squared conduction velocity (θ 2 ) from 2.11±1.1 to 1.72±0.9 (m/s) 2 ( P =.001). With K + depolarization to V m =−70 mV, flecainide further reduced V̇ max from 306±101 to 245±65 V/s and θ 2 from 1.12±0.4 to 0.99±0.6 (m/s) 2 , producing a 2.0-mV hyperpolarizing shift of apparent Na + channel availability curves derived from θ 2 . The addition of 1 μmol isoproterenol to flecainide-superfused fibers at physiological V m increased θ 2 by 8% to 1.84±0.6 (m/s) 2 ( P <.01) without altering V̇ max . At −70 mV, the addition of isoproterenol magnified the flecainide-induced reduction of V̇ max an additional 24% to 185±52 V/s ( P <.01) and θ 2 by 17% to 0.82±0.5 (m/s) 2 ( P =.04), producing an additional 1.8-mV ( P =.002) and 1.9-mV ( P =.002) hyperpolarizing shift in the apparent Na + channel inactivation curves generated from V̇ max and θ 2 , respectively. At physiological V m , the action potential duration (APD 95 ) was reduced from 307±35 to 269±27 ms ( P <.001) by flecainide and subsequently to 217±4 ms ( P <.001) with isoproterenol addition. With 12 mmol/L K + , APD 95 decreased from 198±23 to 182±17 ms ( P =.005) with flecainide and to 164±10 ms ( P =.004) with isoproterenol. Conclusions At depolarized V m , isoproterenol amplified the flecainide-induced reduction of V̇ max and θ 2 , suggesting a further adrenergic-mediated reduction of Na + current. Consequently, the synergy between catecholamines and flecainide at depolarized V m and the shortened APD 95 could facilitate arrhythmogenesis in the presence of underlying ischemia.

Background Adventitial gene transfer may serve as a tool to study vascular biology and may have therapeutic potential. We investigated the hypothesis that adenovirus-mediated transfer of the gene for endothelial nitric oxide synthase (eNOS) to the adventitia would alter vascular reactivity. Methods and Results Rabbit carotid arteries were surgically isolated and adenoviral vectors encoding eNOS (AdeNOS) or β-galactosidase instilled into the periarterial sheath at a concentration of 1×10 10 pfu/mL. Arteries were harvested 4 days later for immunostaining, NOS enzymatic assay, measurement of cGMP, and vasomotor studies. Transgene expression in the adventitia was confirmed by histochemistry for β-galactosidase and immunostaining for eNOS with a monoclonal antibody. Calcium-dependent NOS enzymatic activity and cGMP levels were significantly greater in the AdeNOS-transduced arteries. Maximal contractions to phenylephrine (10 −5 mol/L) were diminished in the AdeNOS-transduced arteries (4.6±0.2 versus 5.6±0.2 g; P <.05), but in the presence of the eNOS inhibitor N G -monomethyl- l -arginine (3×10 −4 mol/L) there was no difference between the two groups (7.1±0.2 versus 7.5±0.3 g; P =NS). Relaxations to calcium ionophore obtained during submaximal contractions to phenylephrine were significantly enhanced in the AdeNOS-transduced arteries (−log EC 50 , 7.77±0.08 versus 7.45±0.07; P <.02). Conclusions We conclude that eNOS gene transfer to the adventitia alters vascular reactivity, as demonstrated by diminished contractile responses to phenylephrine and enhanced relaxations to calcium ionophore. This may represent a therapeutic strategy for vascular diseases characterized by decreased bioavailability of NO.

Background Cardiac mortality and myocardial infarction (MI) rates are used to evaluate the efficacy of coronary artery bypass grafting (CABG) and percutaneous transluminal coronary angioplasty (PTCA). We compared 5-year cardiac mortality and MI rates in 1829 patients with multivessel disease randomized to CABG or PTCA. Methods and Results The 5-year cardiac mortality rate was 8.0% in patients assigned to PTCA compared with 4.9% in those assigned to CABG (relative risk [RR] of 1.55 with a 95% confidence interval [CI] of 1.07 to 2.23; P =.022). In a subgroup of 1476 nondiabetic patients, there were no significant differences between treatment groups in cardiac mortality either overall (4.6% versus 4.2%; RR=1.04, 95% CI, 0.65 to 1.66; P =.908) or in subgroups based on symptoms, left ventricular function, number of diseased vessels, or stenotic proximal left anterior descending artery. The two treatment groups had similar event rates for the combined end point of cardiac death or MI. The RR for cardiac mortality in 264 patients who sustained an MI compared with those who did not was 5.9 ( P <.001). MIs were more common after CABG during index hospitalization ( P =.004), but in the PTCA group, they were more common after discharge ( P <.001). Conclusions The Bypass Angioplasty Revascularization Investigation (BARI) trial indicates 5-year cardiac mortality in patients with multivessel disease was significantly greater after initial treatment with PTCA than with CABG. The difference was manifest in diabetic patients on drug therapy. There were no significant differences overall for the composite end point of cardiac mortality or MI between treatment groups or for cardiac mortality in nondiabetic patients regardless of symptoms, left ventricular function, number of diseased vessels, or stenotic proximal left anterior descending artery.

Background The optimal timing for surgery in patients with mitral regurgitation is disputed. Because of the frequency of left ventricular dysfunction, which is difficult to predict, early surgery has been recommended, but its potential benefits have not been demonstrated. Methods and Results The outcomes of 221 patients (mean age, 65±13 years; 71% males) with flail leaflets diagnosed with two-dimensional echocardiography between 1980 and 1989 who were eligible for operation were analyzed. Group I comprised 63 patients who had early mitral valve surgery (within 1 month after diagnosis). Group II comprised 158 patients initially treated conservatively (80 of whom were operated on later). Group I patients were younger ( P =.009), had more symptoms ( P <.0001), and were more frequently in atrial fibrillation ( P =.023) than group II patients. There was no difference in ejection fraction between the groups. The early surgery strategy was followed by an improved overall survival rate ( P= .028) and a lower incidence of cardiovascular deaths ( P =.025), congestive heart failure ( P =.046), and new chronic atrial fibrillation ( P =.032), as confirmed by multivariate analysis (adjusted risk ratios of 0.31, 0.18, 0.38, and 0.05, respectively; all P< .02). Conclusions In patients with mitral regurgitation due to flail leaflets, the strategy of early surgery versus conservative management is associated with an improved long-term survival rate, decreased cardiac mortality, and decreased morbidity after diagnosis. This outcome advantage suggests that early surgery is a reasonable treatment option to be considered in low-risk candidates with repairable valves and severe mitral regurgitation.

BackgroundInotropic drugs are often used to treat acute, severe heart failure resulting from acute myocardial infarction and other unstable coronary artery syndromes. However, catecholamine inotropic agents may potentiate coronary thrombosis via a platelet α2-adrenergic mechanism, thus exacerbating the original problem. The present studies were designed to determine whether the nonadrenergic inotropic and vasodilator drug amrinone, which elevates platelet cAMP levels, would both inhibit human platelet Ca2+mobilization and adhesion molecule expression ex vivo and protect against experimental coronary thrombosis in vivo in dogs.Methods and ResultsHuman platelets in suspension were preincubated with amrinone 2.5 to 15 μg/mL; stimulated with the agonists thrombin 0.1 U/mL, ADP 10−6mol/L, or arginine vasopressin 10−7mol/L; and studied for Ca2+mobilization, glycoprotein IIb/IIIa activation, and P-selectin expression by fluorescent flow cytometry methods. Experimental coronary thrombosis in vivo was studied in an open-chest dog model with critical coronary artery stenosis and deep vessel wall injury. Results showed that at the cellular level, amrinone inhibited agonist-induced Ca2+mobilization and had modest inhibitory effects on adhesion molecule expression. In vivo in dogs, intravenous amrinone 2 mg/kg plus infusion at 20 μg·kg−1·min−1completely abolished coronary thrombosis.ConclusionsThe fact that amrinone inhibited human platelet activation at the cellular level and protected against experimental coronary thrombosis in vivo in dogs suggests a potentially advantageous antithrombotic action for this inotropic and vasodilator drug.