摘要:

Background—Symptomatic prolonged sinus pauses on termination of atrial fibrillation (AF) are an indication for pacemaker implantation. We evaluated sinus node function and clinical outcome in patients with prolonged sinus pauses on termination of arrhythmia who underwent ablation of paroxysmal AF.Methods and Results—Twenty patients with paroxysmal AF and prolonged sinus pauses (≥3 seconds) on termination of AF underwent ablation between May 1995 and November 2002. Patients with sinus pauses independent of episodes of AF were excluded from the analysis. The procedure included pulmonary vein and linear atrial ablation. After ablation, sinus node function was assessed during the first week and at 1, 3, and 6 months, by 24-hour ambulatory monitoring to determine the mean heart rate and heart rate range, and by exercise testing to determine the maximal heart rate. Corrected sinus node recovery time was determined at the completion of ablation and at 24.0±11.3 months at 600 and 400 ms. After AF ablation, there was a significant improvement of sinus node function, with an increase in the mean heart rate (P=0.001), maximal heart rate (P<0.0001), and heart rate range (P<0.0001). The corrected sinus node recovery time decreased in all patients evaluated at 600 ms (P=0.016) and 400 ms (P=0.019). At 26.0±17.6 months, 18 patients (85%) had no recurrence of AF (in the absence of medication), with no symptoms attributable to bradycardia or sinus pauses on ambulatory monitoring. Two patients had infrequent episodes of AF, 1 requiring pacemaker implantation.Conclusion—Prolonged sinus pauses after paroxysms of AF may result from depression of sinus node function that can be eliminated by curative ablation of AF. This is accompanied by improvement in parameters of sinus node function, suggesting reverse remodeling of the sinus node.

ISSN:0009-7322    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background—Complement activation mediates myocardial damage that occurs during ischemia and reperfusion through multiple pathways. We performed 2 separate, parallel, double-blind, placebo-controlled trials to determine the effects of pexelizumab (a novel C5 complement monoclonal antibody fragment) on infarct size in patients receiving reperfusion therapy: COMPlement inhibition in myocardial infarction treated with thromboLYtics (COMPLY) and COMplement inhibition in Myocardial infarction treated with Angioplasty (COMMA). The COMPLY trial is reported here.Methods and Results—Overall, 943 patients with acute ST-segment elevation myocardial infarction (MI) (20% with isolated inferior MI) receiving fibrinolysis were randomly assigned <6 hours after symptom onset to placebo, pexelizumab 2.0-mg/kg bolus, or pexelizumab 2.0-mg/kg bolus plus 0.05 mg/kg per h for 20 hours. Infarct size determined by creatine kinase–MB area under the curve was the primary analysis, which included patients who received at least some study drug and fibrinolysis (n=920). The median infarct size did not differ by treatment (placebo, 5230; bolus, 4952; bolus plus infusion, 5557 [ng/mL] · h; bolus versus placebo,P=0.85; bolus plus infusion versus placebo,P=0.81), nor did the 90-day composite incidence of death, new or worsening congestive heart failure, shock, or stroke (placebo, 18.6%; bolus, 18.4%; bolus plus infusion, 19.7%). Pexelizumab inhibited complement for 4 hours with bolus-only dosing and for 20 to 24 hours with bolus-plus-infusion dosing, with no increase in infections.Conclusions—When used adjunctively with fibrinolysis, pexelizumab blocked complement activity but reduced neither infarct size by creatine kinase–MB assessment nor adverse clinical outcomes.

ISSN:0009-7322    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background—Complement, activated during myocardial ischemia and reperfusion, causes myocardial damage through multiple processes. The COMplement inhibition in Myocardial infarction treated with Angioplasty (COMMA) trial was performed to determine the effect of pexelizumab, a C5 complement inhibitor, on infarct size in patients with ST-segment–elevation myocardial infarction (MI) undergoing primary percutaneous coronary intervention.Methods and Results—In COMMA, 960 patients with MI (20% isolated inferior MI) were randomized to placebo, pexelizumab 2.0-mg/kg bolus, or pexelizumab 2.0-mg/kg bolus and 0.05-mg/kg per h infusion for 20 hours. Infarct size by creatine kinase–MB area under the curve, the primary outcome, did not differ significantly between groups (placebo median, 4393; bolus pexelizumab, 4526; bolus plus infusion pexelizumab, 4713 [ng/mL] · h;P=0.89 for bolus versus placebo;P=0.76 for bolus plus infusion versus placebo), nor did the composite of 90-day death, new or worsening heart failure, shock, or stroke (placebo, 11.1%; bolus, 10.7%; bolus plus infusion, 8.5%). The ninety-day mortality rate was significantly lower with pexelizumab bolus plus infusion (1.8% versus 5.9% with placebo; nominalP=0.014); the bolus-only group had an intermediate mortality rate (4.2%).Conclusions—In patients with ST-elevation MI undergoing percutaneous coronary intervention, pexelizumab had no measurable effect on infarct size. However, the significant reduction in mortality suggests that pexelizumab may benefit patients through alternative novel mechanisms and provides impetus for additional investigation.

ISSN:0009-7322    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background—There is clear evidence from numerous randomized trials and their meta-analyses that aspirin reduces risks of first myocardial infarction (MI). Recent data also suggest that other nonsteroidal anti-inflammatory drugs (NSAIDs) may interfere with this benefit of aspirin.Methods and Results—We performed subgroup analysis from a 5-year randomized, double-blind, placebo-controlled trial of 325 mg aspirin on alternate days among 22 071 apparently healthy US male physicians with prospective observational data on use of NSAIDs. A total of 378 MIs were confirmed, 139 in the aspirin group and 239 in the placebo group. Aspirin conferred a statistical extreme (P<0.00001) 44% reduction in risk of first MI. Among participants randomized to aspirin, use of NSAIDs on 1 to 59 d/y was not associated with MI (multivariable adjusted relative risk [RR], 1.21; 95% confidence interval [CI], 0.78 to 1.87), whereas the use of NSAIDs on ≥60 d/y was associated with MI (RR, 2.86; 95% CI, 1.25 to 6.56) compared with no use of NSAIDs. In the placebo group, the RRs for MI across the same categories of NSAID use were 1.14 (95% CI, 0.81 to 1.60) and 0.21 (95% CI, 0.03 to 1.48).Conclusions—These data suggest that regular but not intermittent use of NSAIDs inhibits the clinical benefits of aspirin. Chance, bias, and confounding remain plausible alternative explanations, despite the prospective design and adjustment for covariates. Nonetheless, we believe the most plausible interpretation of the data to be that regular but not intermittent use of NSAIDs inhibits the clinical benefit of aspirin on first MI.

ISSN:0009-7322    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background—During the past quarter century, advances in treatment of cardiovascular disease have occurred that might potentially benefit survivors of sudden cardiac arrest (SCA). Little is known, however, about the temporal patterns in long-term survival among persons resuscitated from SCA. We hypothesized that long-term survival would improve over time and that this temporal pattern would be most evident for cardiac causes of death.Methods and Results—The investigation was a retrospective cohort study of survival among persons who were discharged alive from the hospital after resuscitation from out-of-hospital SCA due to heart disease in King County, Wash, between May 1, 1976, and December 31, 2001 (n=2035). Calendar time was divided into four 5-year intervals: 1976 to 1980, 1981 to 1985, 1986 to 1990, and 1991 to 1995, and one 6-year interval, 1996 to 2001. Age-adjusted survival curves were constructed, and Cox proportional-hazards regression was used to compute hazard ratios (HRs) for the association between mortality and time period. During 11 201 person-years of follow-up, 1334 persons died. Compared with the initial time period, the HR for total mortality was 0.86 (95% confidence interval, 0.73 to 1.01) for 1981 to 1985, 0.82 (0.69 to 0.96) for 1986 to 1990, 0.66 (0.55 to 0.79) for 1991 to 1995, and 0.58 (0.47 to 0.71) for 1996 to 2001 (HR for trend=0.87 [0.84 to 0.91] for each successive time period). In analyses that assessed cardiac mortality, an even stronger temporal association was evident (HR for trend=0.79 [0.75 to 0.84]).Conclusions—Long-term survival after resuscitation from SCA improved steadily over time in this cohort. To continue this trend, future studies should identify circumstances in which proven treatments are underutilized as well as investigate new therapies that might benefit survivors of SCA.

ISSN:0009-7322    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background—Although no data exist on the effect of altitude exposure on coronary flow reserve (CFR), patients with coronary artery disease (CAD) are advised not to exceed moderate altitudes of ≈2500 m above sea level. We studied the influence of altitude on myocardial blood flow (MBF) in controls and CAD patients.Methods and Results—In 10 healthy controls and 8 patients with CAD, MBF was measured by positron emission tomography and15O-labeled water at rest, during adenosine stress, and after supine bicycle exercise. This protocol was repeated during inhalation of a hypoxic gas mixture corresponding to an altitude of 4500 m (controls) and 2500 m (CAD). Workload was targeted to comparable heart rate–blood pressure products at normoxia and hypoxia. Resting MBF increased significantly in controls at 4500 m (+24%,P<0.01) and in CAD patients at 2500 m (+24%,P<0.05). Altitude had no influence on adenosine-induced hyperemia and CFR. Exercise-induced hyperemia increased significantly in controls (+38%,P<0.01) at 4500 m (despite a reduction in workload, −28%,P<0.0001) but not in CAD patients at 2500 m (moderate decrease in workload, −11%,P<0.05). Exercise-induced reserve was preserved in controls (+10%,P=NS) but decreased in CAD patients (−18%,P<0.005).Conclusions—At 2500 m altitude, there is a significant decrease in exercise-induced reserve in CAD patients, indicating that compensatory mechanisms might be exhausted even at moderate altitudes, whereas healthy controls have preserved reserve up to 4500 m. Thus, patients with CAD and impaired CFR should be cautious when performing physical exercise even at moderate altitude.

ISSN:0009-7322    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background—Scintigraphic myocardial perfusion imaging is the most widely used noninvasive modality for the detection of coronary artery disease (CAD). A technique for direct imaging of exercise-induced myocardial ischemia is highly desirable and preferable over perfusion imaging but is presently unavailable. We evaluated the feasibility and diagnostic accuracy of direct imaging of exercise-induced myocardial ischemia with fluorine-18-2-deoxyglucose (18FDG).Methods and Results—Twenty-six patients with known or suspected CAD and no prior myocardial infarction underwent simultaneous myocardial perfusion and ischemia imaging after the intravenous injection of Tc-99m-sestamibi (99mTc-sestamibi) and18FDG at peak exercise. Rest perfusion imaging was carried out separately. All patients underwent coronary angiography. Exercise18FDG myocardial images were compared with exercise-rest99mTc-sestamibi images and coronary angiography. Of 22 patients with ≥50% narrowing of ≥1 coronary arteries, 18 had perfusion abnormalities (sensitivity 82%) whereas 20 had abnormal myocardial18FDG uptake (sensitivity 91%,P=NS). Perfusion abnormalities were seen in myocardial segments corresponding to 25 vascular territories of a total of 51 vessels with ≥50% luminal narrowing in 22 patients (sensitivity 49%), whereas increased18FDG uptake was seen in 34 vascular territories (sensitivity 67%,P=0.008).18FDG images were of high quality and easy to interpret but required simultaneous perfusion images for localizing abnormal myocardial18FDG uptake.Conclusions—Exercise-induced myocardial ischemia can be imaged directly with18FDG. Combined exercise18FDG-99mTc-sestamibi imaging provides a better assessment of exercise-induced myocardial ischemia compared with exercise-rest perfusion imaging. Direct ischemia imaging eliminates some of the limitations of presently used myocardial perfusion imaging. Large-scale clinical studies are warranted.

ISSN:0009-7322    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background—Resting regional wall-motion abnormalities do not reliably distinguish ischemic from nonischemic cardiomyopathy. Dobutamine stress echocardiography with use of the wall-motion score index (WMSI) identifies coronary artery disease (CAD) in dilated cardiomyopathy (DCM), but the technique is subjective and further complicated by left bundle-branch block (LBBB). Long-axis motion is sensitive to ischemia and can be assessed quantitatively. We aimed to compare long-axis function with WMSI for detecting CAD in DCM with or without LBBB.Methods and Results—Seventy-three patients with DCM, 48 with CAD (16 with LBBB), and 25 without CAD (10 with LBBB) were studied. Long-axis M-mode, pulsed-wave tissue Doppler echograms (lateral, septal, and posterior walls), and WMSI were assessed at rest and at peak dobutamine stress. Failure to increase systolic amplitude (total amplitude minus postejection shortening) by 2 mm or early diastolic velocity by 1.1 cm/s was the best discriminator for CAD (systolic amplitude, sensitivity 85%, specificity 86%; lengthening velocity, 71% and 94%, respectively;P=NS). Both had greater predictive accuracy than did WMSI (sensitivity 67%, specificity 76%;P<0.001). The predictive accuracy of changes in septal long-axis function was similar to those of average long-axis function (systolic amplitude cutoff=1.5 mm, lengthening velocity cutoff=1.5 cm/s). However in LBBB, systolic amplitude proved to be the only significant discriminator for CAD, with sensitivity and specificity reaching 94% and 100%, respectively (P<0.01 versus early diastolic lengthening velocity).Conclusions—Quantified stress long-axis function identifies CAD in DCM with greater sensitivity and specificity than does standard WMSI, particularly in the presence of LBBB.

ISSN:0009-7322    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background—Retrospective postinfarction studies revealed that decreased heart rate turbulence (HRT) indicates increased risk for subsequent death. This is the first prospective study to validate HRT in a large cohort of the reperfusion era.Methods and Results—One thousand four hundred fifty-five survivors of an acute myocardial infarction (age <76 years) in sinus rhythm were enrolled. HRT onset (TO) and slope (TS) were calculated from Holter records. Patients were classified into the following HRT categories: category 0 if both TO and TS were normal, category 1 if either TO or TS was abnormal, or category 2 if both TO and TS were abnormal. The primary end point was all-cause mortality. During a follow-up of 22 months, 70 patients died. Multivariately, HRT category 2 was the strongest predictor of death (hazard ratio, 5.9; 95% CI, 2.9 to 12.2), followed by left ventricular ejection fraction (LVEF) ≤30% (4.5; 2.6 to 7.8), diabetes mellitus (2.5; 1.6 to 4.1), age ≥65 years (2.4; 1.5 to 3.9), and HRT category 1 (2.4; 1.2 to 4.9). LVEF ≤30% had a sensitivity of 27% at a positive predictive accuracy level of 23%. The combined criteria of LVEF ≤30%, HRT category 2 or LVEF >30%, age ≥65 years, diabetes mellitus, and HRT category 2 had a sensitivity of 24% at a positive predictive accuracy level of 37%. The combined criteria of LVEF ≤30% or LVEF >30%, age ≥65 years, diabetes mellitus, and HRT category 1 or 2 had a sensitivity of 44% at a positive predictive accuracy level of 23%.Conclusions—HRT is a strong predictor of subsequent death in postinfarction patients of the reperfusion era.

ISSN:0009-7322    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background—Little is known about blood flow and its relationship to respiration during exercise in patients with total cavopulmonary connection (TCPC).Methods and Results—We studied 11 patients 12.4±4.6 years (mean±SD) of age 5.9±2.8 years (mean±SD) after TCPC operation. Real-time MRI was used to measure blood flow in the superior vena cava (SVC), inferior vena cava (IVC), and ascending aorta under inspiration and expiration during supine lower-limb exercise (rest, 0.5 and 1.0 W/kg) on an ergometer bicycle. IVC and aortic flow increased from 1.60±0.52 and 2.99±0.83 L/min per m2at rest to 2.58±0.71 and 3.97±1.20 L/min per m2at 0.5 W/kg and to 3.25±1.23 and 4.62±1.49 L/min per m2at 1.0 W/kg (P≤0.05). SVC flow remained unchanged. Resting flow in the IVC was greater during inspiration (2.99±1.25 L/min per m2) than during expiration (0.83±0.44 L/min per m2) (inspiratory/mean flow ratio, 1.9±0.5), and retrograde flow was present during expiration (11±12% of mean flow). The predominance of inspiratory flow in IVC diminished with exercise to an inspiratory/mean flow ratio of 1.5±0.2 (P≤0.05) and 1.4±0.3 at 0.5 and 1.0 W/kg, respectively.Conclusions—In the TCPC, circulation IVC and aortic but not SVC flows increase with supine leg exercise. Inspiration facilitates IVC flow at rest but less so during exercise, when the peripheral pump seems to be more important.

ISSN:0009-7322    

出版商:OVID    

年代:2003

数据来源: OVID