Late Intervention on an Occluded Infarct-Related Artery: A Meta-analysis of the Randomized Controlled Trials

Context

Late intervention to open an occluded infarct-related artery (IRA) after initial acute myocardial infarction was postulated to lead to clinical benefit.

Objective

To conduct a meta-analysis of the randomized trials.

Study Selection

Eligibility criteria were: 1) randomized trials comparing percutaneous coronary intervention (PCI) in a totally occluded artery (TIMI flow 0-1) versus medical therapy, 2) in stable post myocardial infarction (MI) patients without spontaneous or low level exercise induced ischemia, 3) trials with a time from the onset of symptoms to randomization >24 hours, but <6 weeks, and 4) trials reporting mortality and recurrent MI as an endpoint. Of 961 citations reviewed, 3 disagreements were easily resolved by discussion and 6 trials were selected for inclusion.

Data Synthesis

The primary endpoint was the composite of recurrent MI or death. The secondary endpoints were the development of heart failure or recurrent myocardial infarction. In a meta-analysis of the 6 trials, which included 2642 patients, late intervention of an IRA had a RR of death or recurrent MI of 1.12 (95% CI 0.91-1.38). Data regarding the development of heart failure was available for 4 trials. In a meta-analysis of these 4 trials, which included 2527 patients, late intervention of an IRA had a RR of 0.79 (95% CI 0.58-1.08). Data regarding the occurrence of recurrent MI was available for 5 trials. In a meta-analysis of these 5 trials, which included 2598 patients, late intervention of an IRA had a RR of 1.28 (95% CI 0.91-1.79).

Conclusions

Our meta-analysis of the currently available randomized data addressing late intervention of an occluded IRA failed to reveal clinical benefit with regard to the clinical endpoints of death, heart failure or reinfarction. The trend towards an increase in reinfarction among the PCI treated patients suggested by the Open Artery Trial (OAT) investigators persisted, but did not achieve statistical significance.

Where does the Occluded Artery Trial leave the late open artery hypothesis?

As of April 2007 the early open artery hypothesis is alive and well, but the late open artery hypothesis is adrift. For the foreseeable future, stable patients with persistent occlusion of the infarct artery late after myocardial infarction, and without severe ischaemia or uncontrollable angina, should be managed initially with optimal medical treatment alone, and not with percutaneous coronary intervention. Efforts should focus on establishing reperfusion earlier, including reducing the time to patient presentation.

Left ventricular end-diastolic pressure and risk of subsequent heart failure in patients following an acute myocardial infarction

Left ventricular end-diastolic pressure (LVEDP) is an important measure of ventricular performance and may identify patients at increased risk for developing late clinical symptoms of heart failure (HF). The primary outcome in this analysis of 744 patients from the Survival and Ventricular Enlargement (SAVE) trial was the development of death or HF over a mean time of 36 months. The mean LVEDP for all patients was 23+/-9 mm Hg, and 75% of participants (n=558) had an LVEDP >15 mm Hg. Patients with an LVEDP >30 mm Hg (n=187) had the highest risk of death or HF (unadjusted hazard ratio, 1.40; 95% confidence interval [CI], 1.00-1.97) when compared with the other 2 cohorts combined (n=603). After adjustment for other known predictors of cardiac risk, LVEDP no longer remained significant (adjusted hazard ratio, 1.12; 95% CI, 0.77-1.65). Elevated LVEDP is common following myocardial infarction; however, it is not an independent predictor of subsequent HF risk. The variability in LVEDP is not fully explained by infarct size and atherosclerotic burden.

Minimizing ventricular pacing to reduce atrial fibrillation in sinus-node disease

BACKGROUND

Conventional dual-chamber pacing maintains atrioventricular synchrony but results in high percentages of ventricular pacing, which causes ventricular desynchronization and has been linked to an increased risk of atrial fibrillation in patients with sinus-node disease.

METHODS

We randomly assigned 1065 patients with sinus-node disease, intact atrioventricular conduction, and a normal QRS interval to receive conventional dual-chamber pacing (535 patients) or dual-chamber minimal ventricular pacing with the use of new pacemaker features designed to promote atrioventricular conduction, preserve ventricular conduction, and prevent ventricular desynchronization (530 patients). The primary end point was time to persistent atrial fibrillation.

RESULTS

The mean (+/-SD) follow-up period was 1.7+/-1.0 years when the trial was stopped because it had met the primary end point. The median percentage of ventricular beats that were paced was lower in dual-chamber minimal ventricular pacing than in conventional dual-chamber pacing (9.1% vs. 99.0%, P<0.001), whereas the percentage of atrial beats that were paced was similar in the two groups (71.4% vs. 70.4%, P=0.96). Persistent atrial fibrillation developed in 110 patients, 68 (12.7%) in the group assigned to conventional dual-chamber pacing and 42 (7.9%) in the group assigned to dual-chamber minimal ventricular pacing. The hazard ratio for development of persistent atrial fibrillation in patients with dual-chamber minimal ventricular pacing as compared with those with conventional dual-chamber pacing was 0.60 (95% confidence interval, 0.41 to 0.88; P=0.009), indicating a 40% reduction in relative risk. The absolute reduction in risk was 4.8%. The mortality rate was similar in the two groups (4.9% in the group receiving dual-chamber minimal ventricular pacing vs. 5.4% in the group receiving conventional dual-chamber pacing, P=0.54).

CONCLUSIONS

Dual-chamber minimal ventricular pacing, as compared with conventional dual-chamber pacing, prevents ventricular desynchronization and moderately reduces the risk of persistent atrial fibrillation in patients with sinus-node disease. (ClinicalTrials.gov number, NCT00284830 [ClinicalTrials.gov].).

Nitric oxide synthase isoform inhibition before whole body ischemia reperfusion in pigs: Vital or protective?

BACKGROUND

Nitric oxide (NO) is a critical regulator of vascular tone, and signal transduction. NO is produced via three unique synthases (NOS); endothelial (eNOS), and neuronal (nNOS) are both constitutively expressed and inducible (iNOS) produced primarily after stimulation. NO has been implicated during and after ischemia reperfusion injury as both a detrimental and cardioprotective mediator. Since cardiopulmonary resuscitation (CPR) in ventricular fibrillation (VF) is a model of whole body ischemia reperfusion injury, it provides an opportunity to assess the effects of NO from the three NOS isoforms.

OBJECTIVE

To determine the differential role of nitric oxide synthase isoforms inhibition in ventricular fibrillation CPR and investigate whether inhibition of the NOS isoforms afford any cardioprotection in this model.

METHODS

Thirty-two pigs, weight range 25-35 kg, were assigned to four groups of eight animals each. The animals were randomized to receive (1) N(G)-nitro-L-arginine methyl ester (LNAME), a non-selective endothelial nitric oxide synthase inhibitor, (2) 1-(2-trifluoromethylphenyl) imidazole (TRIM), a selective neuronal NOS inhibitor, (3) aminoguanidine (AMINOG), a selective inducible NOS inhibitor or (4) saline control (Control) in equal volumes, 30 min before induction of ventricular fibrillation (VF). After 3 min VF with no intervention, the animals received standard chest compressions using an automated chest compression device (Thumper) for 15 min. After 18 min of VF, single doses of vasopressin and bicarbonate were given and defibrillation attempted. Hemodynamics, regional blood flows, and echocardiography and were performed, before and after drug infusion, during CPR, and after return of spontaneous circulation (ROSC).

RESULTS

ROSC for 3 h occurred in 5/8 (63%), 1/8 (13%), 0/8 (0%), and 6/8 (75%) in Control, LNAME, TRIM, and AMINOG treated animals, respectively. After infusion of LNAME, there was a significant increase from baseline in blood pressure [127+/-6 mmHg versus 169+/-3 mmHg, p<0.002] and coronary perfusion pressure [119+/-6 mmHg versus 149+/-6 mmHg, p<0.003]. During CPR, there were no differences among groups in hemodynamics or regional blood flow. In surviving animals, AMINOG had significantly better myocardial function (left ventricular ejection fraction, fractional shortening, and wall motion score index) than control or LNAME treated animals, and attenuated the post-resuscitation hyperemic response in heart and brain.

CONCLUSIONS

Intact basal nNOS activity is vital for survival from whole body ischemia reperfusion injury. iNOS inhibition prior to ischemia reperfusion, protects myocardial function after ROSC and decreases myocardial and brain hyperemic response after ROSC.

Impact of rate-modulated pacing on quality of life and exercise capacity—Evidence from the Advanced Elements of Pacing Randomized Controlled Trial (ADEPT)

BACKGROUND

Ninety-nine percent of pacemakers implanted in the United States include an option for rate modulation.

OBJECTIVE

The purpose of this study was to determine whether dual-chamber rate-modulated pacing, when compared with dual-chamber pacing alone, improved quality of life.

METHODS

This was a single-blind randomized controlled trial comparing dual-chamber with rate-modulated dual-chamber pacing. Patients were enrolled between January 12, 2000, and January 10, 2002, with 1-year follow-up ending December 19, 2002. The study was a U.S. multicenter trial, with 95 sites participating. All patients received a rate modulation-capable dual-chamber pacemaker for standard indications. Patients were screened with an exercise test (Chronotropic Assessment Exercise Protocol) 1 month later. One thousand two hundred seventy-three patients were enrolled; 401 proved ineligible, and 872 (68%) made up the randomized patient cohort. Randomized patients had a mean age of 71 years, 64% were men, and 64% had sinus node dysfunction. Randomization was in a factorial design to (1) dual-chamber rate-modulated pacing versus dual-chamber pacing and (2) automatic mode switching versus no automatic mode switching. The present report is limited to the comparison of rate modulation with no rate modulation (DDDR vs. DDD). The primary endpoint was the score on the Specific Activity Scale, an activity-based cardiovascular disease-specific instrument at 1 year. Secondary endpoints included 6-month treadmill time and additional cardiovascular disease-specific, and generic health-related quality-of-life instruments at 1 year.

RESULTS

At 6 months, patients with rate modulation had a higher peak exercise heart rate (rate modulation 113.3 +/- 19.6, no rate modulation 101.1 +/- 21.1; P <.0001). Total exercise time was not different between groups. At 1 year, there were no significant differences between groups with respect to Specific Activity Scale or the secondary quality-of-life endpoints.

CONCLUSIONS

We conclude that rate modulation is ineffective in improving the functional status or quality of life of patients with a bradycardia indication for dual-chamber pacing.

Pacemakers and Defibrillators: Recent and Ongoing Studies That Impact the Elderly

Since the first implantation of a cardiac pacemaker in the second half of the 20th century, there have been evolutionary and revolutionary advances in the technology developed for patients with heart rhythm disturbances. These advances, however, have instead failed to demonstrate that mimicry of physiology by a pacing system would deliver a longer and better life to its recipient. Indeed, we are just now in the process of developing a new paradigm in pacing that may finally deliver physiology to the hyperbolically named "physiologic pacing." This article will discuss the reasons for the discrepancy between the earlier studies and the more recent ones, as well as a review of implantable cardioverter-defibrillator trials, keeping in focus the special needs of aged heart rhythm device recipients.

Characterization of health-related quality of life in heart failure patients with preserved versus low ejection fraction in CHARM

BACKGROUND

Limited comparative studies assessing the health-related quality of life (HRQL) in heart failure (HF) patients with preserved vs. low ejection fraction (LVEF) have been disparate.

AIMS

The aims of this study were a) to characterize HRQL in a large population of HF patients with preserved and low LVEF and b) to determine the factors associated with worse HRQL.

METHODS

Patients with symptomatic HF (NYHA Class II-IV) enrolled in the Candesartan in Heart Failure: Assessment of Reduction in Mortality and Morbidity (CHARM) HRQL study completed the Minnesota Living with Heart Failure questionnaire at randomization. Patients were stratified into 2 HF cohorts: preserved LVEF (>40%) and low LVEF (<or=40%).

RESULTS

In 2709 of the eligible 2744 (98.6%) patients, the summary scores ranged from 0 to 105 (mean 40.9). There were no differences in overall responses of HF patients with preserved vs. low LVEF (41.1 vs. 40.8). Independent factors associated with worse HRQL in both populations included female gender, younger age, higher body mass index, lower systolic blood pressure, greater symptom burden, and worse functional status.

CONCLUSIONS

In symptomatic HF patients, HRQL is equally impaired in both preserved and low LVEF populations. Targeting improvement in symptoms and HRQL is an important treatment objective in all HF patients.

Coronary intervention for persistent occlusion after myocardial infarction

BACKGROUND

It is unclear whether stable, high-risk patients with persistent total occlusion of the infarct-related coronary artery identified after the currently accepted period for myocardial salvage has passed should undergo percutaneous coronary intervention (PCI) in addition to receiving optimal medical therapy to reduce the risk of subsequent events.

METHODS

We conducted a randomized study involving 2166 stable patients who had total occlusion of the infarct-related artery 3 to 28 days after myocardial infarction and who met a high-risk criterion (an ejection fraction of <50% or proximal occlusion). Of these patients, 1082 were assigned to routine PCI and stenting with optimal medical therapy, and 1084 were assigned to optimal medical therapy alone. The primary end point was a composite of death, myocardial reinfarction, or New York Heart Association (NYHA) class IV heart failure.

RESULTS

The 4-year cumulative primary event rate was 17.2% in the PCI group and 15.6% in the medical therapy group (hazard ratio for death, reinfarction, or heart failure in the PCI group as compared with the medical therapy group, 1.16; 95% confidence interval [CI], 0.92 to 1.45; P=0.20). Rates of myocardial reinfarction (fatal and nonfatal) were 7.0% and 5.3% in the two groups, respectively (hazard ratio, 1.36; 95% CI, 0.92 to 2.00; P=0.13). Rates of nonfatal reinfarction were 6.9% and 5.0%, respectively (hazard ratio, 1.44; 95% CI, 0.96 to 2.16; P=0.08); only six reinfarctions (0.6%) were related to assigned PCI procedures. Rates of NYHA class IV heart failure (4.4% vs. 4.5%) and death (9.1% vs. 9.4%) were similar. There was no interaction between treatment effect and any subgroup variable (age, sex, race or ethnic group, infarct-related artery, ejection fraction, diabetes, Killip class, and the time from myocardial infarction to randomization).

CONCLUSIONS

PCI did not reduce the occurrence of death, reinfarction, or heart failure, and there was a trend toward excess reinfarction during 4 years of follow-up in stable patients with occlusion of the infarct-related artery 3 to 28 days after myocardial infarction. (ClinicalTrials.gov number, NCT00004562 [ClinicalTrials.gov].).

Randomized trial of percutaneous coronary intervention for subacute infarct-related coronary artery occlusion to achieve long-term patency and improve ventricular function: the Total Occlusion Study of Canada (TOSCA)-2 trial

BACKGROUND

In the present study, we sought to determine whether opening a persistently occluded infarct-related artery (IRA) by percutaneous coronary intervention (PCI) in patients beyond the acute phase of myocardial infarction (MI) improves patency and indices of left ventricular (LV) size and function.

METHODS AND RESULTS

Between May 2000 and July 2005, 381 patients with an occluded native IRA 3 to 28 days after MI (median 10 days) were randomized to PCI with stenting (PCI) or optimal medical therapy alone. Repeat coronary and LV angiography was performed 1 year after randomization (n=332, 87%). Coprimary end points were IRA patency and change in LV ejection fraction. Secondary end points included change in LV end-systolic and end-diastolic volume indices and wall motion. PCI was successful in 92%. At 1 year, 83% of PCI versus 25% of medical therapy-only patients had a patent IRA (P<0.001). LV ejection fraction increased significantly (P<0.001) in both groups, with no between-group difference: PCI 4.2+/-8.9 (n=150) versus medical therapy 3.5+/-8.2 (n=136; P=0.47). Median change (interquartile range) in LV end-systolic volume index was -0.5 (-9.3 to 5.0) versus 1.0 (-5.7 to 7.3) mL/m2 (P=0.10), whereas median change (interquartile range) in LV end-diastolic volume index was 3.2 (-8.2 to 13.3) versus 5.3 (-4.6 to 23.2) mL/m2 (P=0.07) in the PCI (n=86) and medical therapy-only (n=76) groups, respectively.

CONCLUSIONS

PCI with stenting of a persistently occluded IRA in the subacute phase after MI effectively maintains long-term patency but has no effect on LV ejection fraction. On the basis of these findings and the lack of clinical benefit in the main Occluded Artery Trial, routine PCI is not recommended for stable patients with a persistently occluded IRA after MI.

Comparative lipid-lowering effects of policosanol and atorvastatin: a randomized, parallel, double-blind, placebo-controlled trial

BACKGROUND

Policosanol, commonly derived from purified sugar cane wax, has been reported to exert lipid-lowering effects. Policosanol is available in the United States as a nutritional supplement despite no US research clinical experience. This trial was designed to rigorously establish the lipid-lowering efficacy of policosanol as monotherapy and its potential additive and possibly synergistic effects when added to statin therapy.

METHODS

A randomized, parallel, double-blind, double-dummy, placebo-controlled design was used. Patients with low-density lipoprotein cholesterol (LDL-C) levels from 140 to 189 mg/dL were assigned into 1 of 4 groups to receive policosanol 20 mg, atorvastatin 10 mg, combination therapy, or placebo for 12 weeks.

RESULTS

A total of 99 patients were examined. Baseline characteristics were similar among all treatment groups. Policosanol (20 mg/d for 12 weeks) did not significantly change plasma total cholesterol, LDL-C, high-density lipoprotein cholesterol, or triglyceride levels when compared with baseline values or with values of placebo-treated patients. Atorvastatin (10 mg/d for 12 weeks) reduced total cholesterol by 27% and LDL-C by 35%. Addition of policosanol to atorvastatin failed to produce any further reduction in lipid levels above that of atorvastatin alone. Policosanol was safe and did not affect liver enzyme or creatinine phosphokinase levels.

CONCLUSIONS

Policosanol did not reduce LDL-C or total cholesterol levels either alone or in combination with atorvastatin. This observation supports the need for systematic evaluation of available products containing policosanol to determine their clinical lipid-lowering efficacy under rigorous experimental conditions. We propose that policosanol should be added to the list of nutritional supplements lacking scientific validity to support their use.

Cardiovascular outcomes with atrial-based pacing compared with ventricular pacing: meta-analysis of randomized trials, using individual patient data

BACKGROUND

Several randomized trials have compared atrial-based (dual-chamber or atrial) pacing with ventricular pacing in patients with bradycardia. No trial has shown a mortality reduction, and only 1 small trial suggested a reduction in stroke. The goal of this review was to determine whether atrial-based pacing prevents major cardiovascular events.

METHODS AND RESULTS

A systematic review was performed of publications since 1980. For inclusion, trials had to compare an atrial-based with a ventricular-based pacing mode; use a randomized, controlled, parallel design; and have data on mortality, stroke, heart failure, or atrial fibrillation. Individual patient data were obtained from 5 of the 8 identified studies, representing 95% of patients in the 8 trials, and a total of 35 000 patient-years of follow-up. There was no significant heterogeneity among the results of the individual trials. There was no significant reduction in mortality (hazard ratio [HR], 0.95; 95% confidence interval [CI], 0.87 to 1.03; P=0.19) or heart failure (HR, 0.89; 95% CI, 0.77 to 1.03; P=0.15) with atrial-based pacing. There was a significant reduction in atrial fibrillation (HR, 0.80; 95% CI, 0.72 to 0.89; P=0.00003) and a reduction in stroke that was of borderline significance (HR, 0.81; 95% CI, 0.67 to 0.99; P=0.035). There was no convincing evidence that any patient subgroup received special benefit from atrial-based pacing.

CONCLUSIONS

Compared with ventricular pacing, the use of atrial-based pacing does not improve survival or reduce heart failure or cardiovascular death. However, atrial-based pacing reduces the incidence of atrial fibrillation and may modestly reduce stroke.

Pacemaker implantation and quality of life in the Mode Selection Trial (MOST)

BACKGROUND

Dual-chamber pacemakers restore AV synchrony compared with ventricular pacemakers, but the effects on health-related quality of life (QOL) are uncertain.

OBJECTIVES

The purpose of this study was to assess the effect of pacemaker implantation, clinical factors, and pacing mode on QOL.

METHODS

The Mode Selection Trial (MOST) randomized 2,010 patients with sinus node dysfunction to rate-modulated right ventricular (VVIR) or dual-chamber (DDDR) pacing. A longitudinal analysis of serial QOL measures (Short Form-36 [SF-36], Specific Activity Scale, and time trade-off utility) was performed. In patients who crossed over from VVIR to DDDR because of severe pacemaker syndrome, the last known QOL prior to crossover was carried forward.

RESULTS

Pacemaker implantation resulted in substantial improvement in almost all QOL measures. Subjects 75 years or older experienced significantly less improvement in functional status and physical component summary scores than did younger subjects. In longitudinal analyses of the effect of pacing mode on QOL, significant improvement in three SF-36 subscales was observed with DDDR pacing compared with VVIR pacing: role physical [62.8 points (95% confidence interval [CI] 60.2, 65.5) vs 56.4 (95% CI 53.7, 59.1)], role emotional [85.0 (95% CI 82.9, 87.0) vs 81.9 (95% CI 79.9, 84.0)], and vitality [51.8 (95% CI 50.3, 53.3) vs 49.3 (95% CI 47.8, 50.7)], but not in other SF-36 subscales, the Specific Activity Scale, or utilities. The gains in QOL were larger than the declines associated with 1 year of aging but smaller than those associated with heart failure.

CONCLUSION

Pacemaker implantation improved health-related QOL. The mode selected was associated with much smaller, but significant, improvements in several domains, particularly role physical function.

Treatment Crossovers Did Not Affect Randomized Treatment Comparisons in the Mode Selection Trial (MOST)

OBJECTIVES

We evaluated the impact of treatment crossovers on study results in the Mode Selection Trial (MOST).

BACKGROUND

The MOST study, a 2,010-patient, 6-year trial comparing dual-chamber pacing (DDDR) and ventricular pacing (VVIR) in sinus node dysfunction, demonstrated no difference in death or stroke and modest reductions in heart failure hospitalization (HFH) and atrial fibrillation (AF) with DDDR pacing. However, a moderate proportion of VVIR-randomized patients were temporarily or permanently crossed over to DDDR pacing.

METHODS

Intent-to-treat (ITT) analyses compared treatment arms by randomized pacing mode. On-treatment analyses used time-dependent covariates to account for all crossovers. All analyses used Cox proportional hazards models and included covariates prespecified in the study design: age, gender, Charlson index, and prior stroke, heart failure, myocardial infarction, supraventricular tachyarrhythmia, and ventricular tachycardia or fibrillation.

RESULTS

Of 996 VVIR-randomized patients, 375 (38%) were DDDR paced at some time, accounting for 27% of follow-up days among all VVIR-randomized patients. Of 1,014 DDDR-randomized patients, 53 (5%) were VVIR paced at some time, accounting for 1.5% of follow-up days among all DDDR-randomized patients. On-treatment analyses showed slightly lower hazard ratios favoring DDDR versus VVIR compared with ITT: death or stroke 0.88 (on-treatment) versus 0.91 (ITT); death 0.94 versus 0.95; stroke 0.74 versus 0.81; HFH 0.72 versus 0.73; and AF 0.72 versus 0.77. Interpretation of treatment effects was unchanged.

CONCLUSIONS

Although treatment crossovers accounted for >25% of follow-up time in the VVIR-randomized group, this did not affect study results. End point comparisons between randomized modes are accurate reflections of DDDR versus VVIR pacing in this study population.

Comparing classifications of death in the Mode Selection Trial: agreement and disagreement among site investigators and a clinical events committee

Clinical events committees (CECs) are the current standard for endpoint adjudication in clinical trials. However, little data exist with which to compare CEC and site investigator determinations or to evaluate internal agreement among CEC members. Using data from the Mode Selection Trial in Sinus Node Dysfunction (MOST), we analyzed classifications of death in order to compare internal agreement among CEC physician reviewers and agreement between the CEC and site investigators. Death was classified at 2 levels: by major cause (cardiac, noncardiac, or unknown) and by minor subclassification of the major classifications. Reviewer agreement was tabulated at the major and minor levels, and standard and weighted kappa statistics were calculated. Disagreement at both levels was also determined. Individual decision-making was tabulated in terms of frequency in classifying death as unknown. All 404 deaths were classified by the CEC. Site investigators determined major classifications in 382 cases and minor classification in 379 cases. The CEC and the site investigators disagreed in classifying 41 cases (10.7%) at the major level and 117 (30.9%) at the minor level. CEC reviewers disagreed internally at the major level in 64 cases (15.8%), at the minor level in 63 cases (15.6%), and at any level in 127 cases (31.4%) (kappa = 0.60, 95% confidence interval (CI) [0.55, 0.66]; weighted kappa = 0.66, 95% CI [0.62, 0.75]). In resolving internal disagreements, the full CEC agreed with 1 of 2 CEC reviewers in 85.9% of cases. Disagreements occurred between site investigators and CEC reviewers in classifying deaths. Endpoint determination and decision-making varied among individual CEC reviewers, but second-tier reviews by the full CEC resolved all disagreements. These findings support continued use of CECs for endpoint adjudication in clinical trials.

The association of the heart failure score with mortality and heart failure hospitalizations in elderly patients: insights from the Mode Selection Trial (MOST)

BACKGROUND

Patient and physician preferences as well as cost favor an increasingly higher threshold for hospital admission for heart failure (HF) treatment. This trend risks masking the severity and prevalence of HF as hospitalization for HF may decrease.

METHODS

Heart Failure Score (HFS) has 4 ordinal subscales assessing (1) HF symptoms, physical signs of left (2) and (3) right HF, and (4) therapy changes for HF. Heart Failure Score was calculated for 1257 of 2010 (63%) patients enrolled in the MOST trial in sinus node dysfunction, who survived and had complete first-year HFS data at 4 postpacemaker implant visits (1, 3, 6, and 12 months). Heart Failure Score was summed and ranged from 0 to 14, with lower scores representing less HF.

RESULTS

There were 1257 patients (median age 74 years [interquartile range 68-79], 47% were women, 61% had hypertension, 20%, diabetes mellitus, and 23%, prior myocardial infarction). The median HFS accumulated during 1 year was 4 (interquartile range 1-8). Of patients with a benign first year, those with a higher HFS were more likely to die during subsequent follow-up compared with patients with lower HFS (hazard ratio 1.07, 95% CI 1.04-1.10 for each 1-point increase, P < .001).

CONCLUSIONS

Increasing HFS is associated with an increased risk of mortality in mostly elderly patients without pre-existing HF. Heart Failure Score may be a useful surrogate HF end point for clinical trials.

Prognostic use of echocardiography 1 year after a myocardial infarction

BACKGROUND

Left ventricular (LV) and right ventricular (RV) function are known predictors of morbidity and mortality after an acute myocardial infarction (MI). However, the prognostic use of a late evaluation of cardiac function after an MI remains unclear.

METHODS

We analyzed echocardiograms obtained 1 year after MI in patients with LV dysfunction at baseline (ejection fraction [EF] < or = 40%) from 291 patients enrolled in the SAVE echocardiographic substudy who did not develop heart failure (HF) or a recurrent MI during this first year. Left ventricular EF and RV fractional area change were assessed.

RESULTS

After a median follow-up of 22 months after the 1-year echocardiogram, a low LVEF (< 30%) at 1 year was associated with an increased risk of death and/or HF (hazards ratio [HR] 2.7, 95% CI 1.3-5.3). Presence of RV dysfunction was also associated with an increased risk of death (HR 8.9, 95% CI 3.5-22.1), development of HF (HR 7.1, 95% CI 3.4-15.0), and the composite end point of death or HF (HR 7.6, 95% CI 4.1-14.2). In multivariate analyses, both low LVEF and RV dysfunction remained independently predictive of the composite end point of death or HF. Patients with biventricular dysfunction were at the greatest risk of death and/or HF (HR 19.4, 95% CI 8.2-46.0) in follow-up.

CONCLUSIONS

In a stable population of survivors of MI, impaired LV and RV function at 1 year after MI are independently and additively predictive of increased risk of HF or death.

Design and methodology of the Occluded Artery Trial (OAT)

Experimental and clinical studies have suggested that late opening of an infarct-related artery (IRA) after myocardial infarction (MI) could improve clinical outcome. However, the suggestive observational data are limited by selection biases. Indeed, most small randomized studies have not demonstrated benefit. Thus, there is no recommendation for routine late opening of the IRA in current national guidelines for management of stable post-MI patients. The OAT is designed to test the hypothesis that opening a totally occluded IRA 3 to 28 days after MI in high-risk asymptomatic patients will improve clinical outcome and be cost-effective. The primary end point is the first occurrence of recurrent MI, hospitalization/treatment of New York Heart Association class IV congestive heart failure, or death. Trial background, design, and preliminary baseline characteristics of 2027 randomized patients are presented. Eligible patients are randomly assigned in equal proportions to optimal evidence-based medical care or optimal care plus late opening of the IRA using percutaneous coronary intervention of the occluded IRA. Treatment groups will be compared using intent-to-treat analysis. The results of OAT should have broad clinical impact by defining an evidence-based approach to the asymptomatic, high-risk, post-MI patient with an occluded IRA. If the efficacy and cost-effectiveness of percutaneous coronary intervention are established, then a policy of routinely seeking and opening persistently occluded IRAs could be advocated. If not, this strategy should be avoided in this large subgroup of post-MI patients.

Treatment and prevention of atrial fibrillation with nonantiarrhythmic pharmacologic therapy

Atrial fibrillation is one of the most frequent heart rhythm disturbances found in clinical practice. Anticoagulation, rate control, cardioversion, and ablative procedures have been the mainstay of treatment. The frequent recurrence of atrial fibrillation and the side effects when antiarrhythmic drugs are used have led to dissatisfaction with available treatment of this arrhythmia. Pharmacologic therapy with angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, statins, and perhaps aldosterone and calcium channel blockers may have a role in the prevention of atrial fibrillation onset and recurrence. We summarize the possible biologic mechanisms and the clinical observations supporting the use of non-antiarrhythmic medications in the prevention of atrial fibrillation.

Clinical and Quality of Life Comparison of Accelerometer, Piezoelectric Crystal, and Blended Sensors in DDDR-Paced Patients with Sinus Node Dysfunction in the Mode Selection Trial (MOST)

INTRODUCTION

Permanent pacemakers are capable of increasing heart rate in response to physical activity by a variety of sensors including accelerometers, piezoelectric crystals, or blended sensors. The impact of these different physiologic sensors on cardiovascular events and quality of life is not known.

METHODS

Of 2,010 patients randomized in the Mode Selection Trial, 1,245 patients were selected with the most commonly used pacemakers with these three sensors. Clinical characteristics and quality of life were compared between groups at baseline, 3 months, and then yearly.

RESULTS

There were 449 patients with an accelerometer sensor device, 682 with a piezoelectric sensor, and 114 with a blended sensor. The groups were similar in terms of age (mean 74 years), gender, and cardiac risk factors but differences existed in weight, heart rate, mitral regurgitation, revascularization history, and drug therapy. The median ventricular pacing frequency was 80% (25th, 75th percentiles 42, 97). After a median follow-up of 33.1 months, the risk of death, heart failure hospitalization, atrial fibrillation, and the combined endpoint of mortality and stroke was not significantly different between the sensor types, after adjustment for baseline differences. Quality of life analyses demonstrated that patients with blended sensors had significantly worse (P < 0.01) physical function than did patients with the other two sensor systems. Moreover, patients receiving blended sensors had the poorest absolute scores, without reaching statistical significance, on 9 of 13 quality of life measures after adjusting for differences in the groups.

CONCLUSION

We found no significant differences among the three most utilized sensors in clinical endpoints. Those patients who received blended sensors had worse physical function quality of life scores. However, clinical selection of the most sophisticated sensor for the most ill patients cannot be excluded as an explanation of these results.

Echocardiographic comparison of cardiopulmonary resuscitation (CPR) using periodic acceleration (pGz) versus chest compression

OBJECTIVE

This investigation compared the effects of conventional cardiopulmonary resuscitation (CPR) using an automated Thumper chest compression device to periodic acceleration CPR (pGz-CPR) on early post-resuscitation ventricular function assessed by echocardiography, in an adult pig model of CPR.

BACKGROUND

Whole body periodic acceleration along the spinal axis (pGz) is a new method of cardiopulmonary resuscitation (CPR). Biomechanical forces and biochemical release produced by pGz impart ventilation and increase blood flow. Our laboratory has reported normal neurological and cardiovascular function 48 h after return of spontaneous circulation in animals that have undergone 22 min of pGz-CPR.

METHODS

Ventricular fibrillation (VF) was induced in 16 animals (25-35 kg). After 3 min of non-interventional period, the animals were randomized to receive either pGz-CPR or Thumper-CPR for 15 min. After 18 min of VF, a single dose of vasopressin and bicarbonate were administered and defibrillation attempted. An echocardiogram was performed at baseline and serially for 6h. Ejection fraction (EF), fractional shortening (FS) and wall motion were assessed by 2D and M-mode echocardiography.

RESULTS

Return of spontaneous circulation to 360 min occurred in 5/8 (62%) of the animals receiving Thumper-CPR and in 7/8 (88%) receiving pGz-CPR. FS and EF were impaired after CPR, but pGz-CPR animals had less impairment than Thumper-CPR animals. Further, wall motion score index (WMSI) was more impaired after Thumper-CPR and remained as such even 6h post-CPR.

CONCLUSION

pGz holds promise as a new method for CPR with better left ventricular (LV) function post-CPR than the more traditional chest compression method.

Association of Prolonged QRS Duration With Death in a Clinical Trial of Pacemaker Therapy for Sinus Node Dysfunction

Background— Prolonged QRS duration (QRSd) is an important prognostic indicator for death and heart failure hospitalization in patients with systolic heart failure. The relationship of baseline QRSd to death and heart failure hospitalization in patients with sinus node dysfunction who require pacemaker therapy is unknown.

Methods and Results— Baseline QRSd from 12-lead ECGs before pacemaker implantation were analyzed in the Mode Selection Trial (MOST), a 6-year, 2010-patient randomized trial of dual-chamber versus ventricular pacing in sinus node dysfunction. Baseline QRSd was ≥120 ms in 23.4% of patients and was associated with older age, lower ejection fraction, cardiomyopathy, and prior heart failure. Adjusted Cox models demonstrated baseline QRSd ≥120 ms was a strong independent predictor of death (hazard ratio [95% CI] 1.35 [1.07, 1.70], P =0.010) but not heart failure hospitalization. The risk of death increased with increased QRSd from 60 to 120 ms ( P =0.002 and hazard ratio [95% CI] 1.14 [1.05, 1.23] for 10-ms increase in this range) after adjustment for other death predictors.

Conclusions— Baseline QRSd ≥120 ms was associated with increased risk of death during pacemaker therapy for sinus node dysfunction.

The national cholesterol education program diet vs a diet lower in carbohydrates and higher in protein and monounsaturated fat: a randomized trial

BACKGROUND

In the United States, obesity is a major clinical and public health problem causing diabetes, dyslipidemia, and hypertension, as well as increasing cardiovascular and total mortality. Dietary restrictions of calories and saturated fat are beneficial. However, it remains unclear whether replacement of saturated fat with carbohydrates (as in the US National Cholesterol Education Program [NCEP] diet) or protein and monounsaturated fat (as in our isocaloric modified low-carbohydrate [MLC] diet, which is lower in total carbohydrates but higher in protein, monounsaturated fat, and complex carbohydrates) is optimal.

METHODS

We randomized 60 participants (29 women and 31 men) to the NCEP or the MLC diet and evaluated them every 2 weeks for 12 weeks. They were aged 28 to 71 years (mean age, 44 years in the NCEP and 46 years in the MLC group). A total of 36% of participants from the NCEP group and 35% from the MLC group had a body mass index (calculated as weight in kilograms divided by the square of height in meters) greater than 27. The primary end point was weight loss, and secondary end points were blood lipid levels and waist-to-hip ratio.

RESULTS

Weight loss was significantly greater in the MLC (13.6 lb) than in the NCEP group (7.5 lb), a difference of 6.1 lb (P = .02). There were no significant differences between the groups for total, low density, and high-density lipoprotein cholesterol, triglycerides, or the proportion of small, dense low-density lipoprotein particles. There were significantly favorable changes in all lipid levels within the MLC but not within the NCEP group. Waist-to-hip ratio was not significantly reduced between the groups (P = .27), but it significantly decreased within the MLC group (P = .009).

CONCLUSIONS

Compared with the NCEP diet, the MLC diet, which is lower in total carbohydrates but higher in complex carbohydrates, protein, and monounsaturated fat, caused significantly greater weight loss over 12 weeks. There were no significant differences between the groups in blood lipid levels, but favorable changes were observed within the MLC diet group.

Heart failure hospitalization is more common in pacemaker patients with sinus node dysfunction and a prolonged paced QRS duration

OBJECTIVES

The purpose of this study was to determine whether a prolonged paced QRS duration increases the risk of cardiac dysfunction.

BACKGROUND

Right ventricular apical pacing mimics left bundle branch block, results in a prolonged QRS duration of variable duration, and causes ventricular desynchronization.

METHODS

In the Mode Selection Trial (MOST), QRS duration was measured in patients who had at least one paced ventricular complex recorded on 12-lead ECG within 3 months of enrollment (early) and after 9 months (late). Clinical endpoints including heart failure hospitalization, mortality, and atrial fibrillation were analyzed. A total of 1,026 patients were included in the analysis. Median age was 75 years (25th, 75th percentiles = 69, 80) and median ejection fraction prior to implant was 55% (45, 60). The cumulative percent ventricular pacing (DDDR and VVIR) was 81% over a median follow-up of 33 months. During period, 123 patients had heart failure hospitalization, 197 died, and 261 patients had atrial fibrillation.

RESULTS

Cox proportional hazards models demonstrated that paced QRS duration was a strong predictor of heart failure hospitalization (hazard ratio 1.15; 95% confidence interval 1.07,1.23) for each 10-ms increase in paced QRS duration (P = .001). The increased risk was unaffected by adjustment for other known predictors of heart failure hospitalization in the study. Paced QRS duration was not significant for mortality (P = .41) or atrial fibrillation (P = .20) when baseline QRS duration and other predictors were included.

CONCLUSIONS

Paced QRS duration is a significant, independent predictor of heart failure hospitalization in patients with sinus node dysfunction. A very long paced QRS duration is associated with increased heart failure hospitalization.

Cost-effectiveness of dual-chamber pacing compared with ventricular pacing for sinus node dysfunction

BACKGROUND

Compared with single-chamber ventricular pacing, dual-chamber pacing can reduce adverse events and, as a result, improve quality of life in patients paced for sick sinus syndrome. It is not clear, however, how these benefits compare with the increased cost of dual-chamber pacemakers.

METHODS AND RESULTS

We used 4-year data from a 2010-patient, randomized trial to estimate the incremental cost-effectiveness of dual-chamber pacing compared with ventricular pacing and then projected these findings over the patients' lifetimes by using a Markov model that was calibrated to the first 5 years of in-trial data. To assess the stability of the findings, we performed 1000 bootstrap analyses and multiple sensitivity analyses. During the first 4 years of the trial, dual-chamber pacemakers increased quality-adjusted life expectancy by 0.013 year per subject at an incremental cost-effectiveness ratio of 53,000 dollars per quality-adjusted year of life gained. Over a lifetime, dual-chamber pacing was projected to increase quality-adjusted life expectancy by 0.14 year with an incremental cost-effectiveness ratio of approximately 6800 dollars per quality-adjusted year of life gained. In bootstrap analyses, dual-chamber pacing was cost-effective in 91.9% of simulations at a threshold of 50,000 dollars per quality-adjusted year of life and in 93.2% of simulations at a threshold of 100,000 dollars. Its cost-effectiveness ratio was also below this threshold in numerous sensitivity analyses that varied key estimates.

CONCLUSIONS

For patients with sick sinus syndrome requiring pacing, dual-chamber pacing increases quality-adjusted life expectancy at a cost that is generally considered acceptable.

Impact of diabetes on mortality in patients with myocardial infarction and left ventricular dysfunction

BACKGROUND

Diabetes is a major risk factor for developing coronary heart disease. In patients with diabetes who survived myocardial infarction (MI), less is known about subsequent morbidity and mortality. We evaluated the effects of diabetes in post-MI patients with left ventricular dysfunction on cardiovascular events and death.

METHODS

The Survival and Ventricular Enlargement, a randomized, double-blind, placebo-controlled multicenter trial, evaluated the efficacy of captopril vs placebo in 2231 patients following acute MI with left ventricular dysfunction defined as an ejection fraction less than or equal to 40%. Patients were randomly assigned to captopril or placebo 3 to 16 days following MI and were followed up for 2 to 5 years (mean, 3.5 years).

RESULTS

Among the 2231, 496 (22.2%) were patients with a history of diabetes, of which 168 (33.9%) were treated with insulin. Patients with diabetes were significantly older; more likely to be women; have a history of prior MI or hypertension; be obese or manifest Killip class II or greater; and have higher systolic blood pressure, pulse pressure, and heart rate, as well as lower ejection fraction. During follow-up, 31.3% of patients with diabetes and 20.1% of nondiabetic patients died (P<.001). Furthermore, 50% of the patients with diabetes had at least 1 major cardiovascular event compared with 32.3% among the nondiabetic patients (P<.001). In multivariate analysis that adjusted for all significant differences in baseline characteristics, patients with diabetes had a 39% higher total mortality (P = .001) and 49% more cardiovascular events (P = .001). Among the patients with diabetes, baseline insulin treatment was associated with a greater risk of death (41.1% vs 26.2%; P = .001) and cardiovascular events (58.3% vs 45.7%; P = .008).

CONCLUSIONS

In patients who survived MI with left ventricular dysfunction, diabetes increased risk of death from all causes even after controlling for differences in other risk factors. Patients with diabetes treated with insulin have a particularly higher mortality risk. Patients with diabetes who survived MI with left ventricular dysfunction, in particular those receiving insulin, are at high risk of subsequent mortality and cardiovascular events and thus require intensive risk factor modification, as well as evaluation for novel therapies.

Cardiac pacing for bradycardia support: Evidence-based approach to pacemaker selection and programming

The vast majority of pacemakers implanted in the United States for the treatment of symptomatic bradycardia are dual-chamber systems with a complex array of functions, such as rate responsiveness, dynamic atrioventricular delay, and automatic mode switching. Basic hemodynamic studies have convincingly demonstrated the superiority of maintaining atrioventricular synchrony. However, clinical trials have failed to demonstrate the impressive results expected based on physiologic data. The most recent randomized clinical trials have demonstrated that dual-chamber devices, when compared with single-chamber ventricular pacing, do not prevent mortality or stroke, and lead to an unexpectedly small reduction in heart failure hospitalizations. Although improvements in quality of life have not been consistently found when comparing ventricular-based versus atrial-based pacing, a reduction in the incidence of newly diagnosed atrial fibrillation in dual chamber-paced patients has been reported by most trials. Dual-chamber pacing has been reported to reduce pacemaker syndrome in US trials. The addition of rate modulation, in spite of attempting to replicate the normal response to exercise, has not shown a consistently positive impact on quality of life or treadmill time. The use of pacemakers for the treatment of vasovagal syncope is controversial. Adding dual-chamber sensing ability to current implanted defibrillators considerably reduces the number of inappropriate shocks but may increase mortality if not programmed to minimize ventricular stimulation.

Body image changes associated with dual-chamber pacemaker insertion in women

PURPOSE

The study's purpose was to examine body image changes in subjects participating in a long-term multicenter pacemaker trial.

METHODS

At study closeout, 383 adults, all of whom had received a dual-chamber pacemaker, completed questionnaires evaluating what effect their pacemaker or pacemaker site and scar had on them or their spouses or significant others.

RESULTS

Most reported that their pacemaker did not change the way they or their spouses or significant others felt about their body (73.2% and 93.5%, respectively). Most (87.1%) denied feeling differently because of the pacemaker site and scar. Most were not concerned how their clothes fit or about wearing a swimsuit (92.0% and 90.7%, respectively). Women were more concerned about how the pacemaker site and scar made them feel about their body (P =.001), clothes fitting (P =.002), and wearing a swimsuit (P =.004). Men were more concerned with how their spouses or significant others perceived them postimplantation (P =.021).

CONCLUSIONS

Most subjects did not express undue concern about changes in body image.

Randomized trials of vitamin E in the treatment and prevention of cardiovascular disease

BACKGROUND

Observational epidemiological studies consistently show that individuals who choose to take high amounts of vitamin E through diet or supplements experience cardiovascular benefits, for which basic research provides plausible mechanisms. However, because the size of the postulated benefit is small to moderate, the confounding inherent in observational studies is as great as the effect size. Before the availability of randomized evidence, about 1 in 4 adults was taking vitamin E supplements in the United States.

METHODS

We conducted a computerized search of the English-language literature from 1990 to the present and found 7 large-scale randomized trials of the effectiveness vitamin E in the treatment and prevention of cardiovascular disease. Data were available on myocardial infarction, stroke, or cardiovascular death.

RESULTS

Six of the 7 trials showed no significant effect of vitamin E on cardiovascular disease. In an overview, vitamin E had neither a statistically significant nor a clinically important effect on any important cardiovascular event (odds ratio [OR], 0.98; 95% confidence interval [CI], 0.94-1.03) or its components: nonfatal myocardial infarction (OR, 1.00; 95% CI, 0.92-1.09), nonfatal stroke (OR, 1.03; 95% CI, 0.93-1.14), or cardiovascular death (OR, 1.00; 95% CI, 0.94-1.05).

CONCLUSIONS

The ORs and CIs provide strong support for a lack of statistically significant or clinically important effects of vitamin E on cardiovascular disease. The use of agents of proven lack of benefit, especially those easily available over the counter, may contribute to underuse of agents of proven benefit and failure to adopt healthy lifestyles.

Antecedent hypertension and the effect of captopril on the risk of adverse cardiovascular outcomes after acute myocardial infarction with left ventricular systolic dysfunction: Insights from the Survival and Ventricular Enlargement Trial

BACKGROUND

Hypertension is a well-established risk factor for myocardial infarction (MI), but its prognostic importance in survivors of an acute MI is less clear.

METHODS

We used Cox proportional hazards models to examine the risk of any major cardiovascular event (cardiovascular death, heart failure, recurrent MI, or stroke)-combined or individual components-and all-cause death and evaluate the efficacy of captopril in 906 patients with hypertension and 1325 patients without hypertension in the Survival and Ventricular Enlargement (SAVE) clinical trial. All patients had survived an acute MI with resultant left ventricular (LV) systolic dysfunction, but without overt heart failure, and were randomized within 3 to 16 days after the index MI to receive either captopril or placebo. The mean (+/- SD) follow-up period was 42 +/- 10 months.

RESULTS

After adjustment for known risk factors, medication use at enrollment, and baseline systolic blood pressure, patients with hypertension had a significant increase in the risk of experiencing a combined cardiovascular event (47.7% vs 31.3%; hazard ratio [HR], 1.49; 95% CI, 1.28-1.74), cardiovascular death (23.4% vs 15.9%; HR, 1.40; 95% CI, 1.12-1.74), heart failure (27.7% vs 15.5%; HR, 1.64; 95% CI, 1.34-2.02), and all-cause death (27.4 vs 19.3%; HR, 1.25; 95% CI, 1.02-1.53), and a similar but statistically non-significant increase in the risk of non-fatal or fatal recurrent MI (17.4% vs 10.9%; HR, 1.27; 95% CI, 0.98-1.65), and non-fatal or fatal stroke (5.0% vs 3.6%; HR, 1.31; 95% CI, 0.81-2.09). Captopril resulted in similar benefits for both patients with and patients without hypertension. The number of combined cardiovascular events prevented for every 100 patients treated with captopril was 7.0 (95% CI, 0.5-13.5) in patients with hypertension and 7.5 (95% CI, 2.6-12.5) in patients without hypertension.

CONCLUSIONS

In survivors of an acute MI with LV systolic dysfunction, antecedent hypertension was associated with a greater risk of subsequent adverse cardiovascular events, not directly explained by elevated blood pressure levels. Captopril use was beneficial in both patients with and patients without hypertension.

Effect of antecedent systemic hypertension on subsequent left ventricular dilation after acute myocardial infarction (from the Survival and Ventricular Enlargement trial)

Whether antecedent systemic hypertension influences the risk of subsequent left ventricular (LV) dilation in patients after an acute myocardial infarction with LV systolic dysfunction is unclear. We assessed echocardiographic evidence of ventricular remodeling from baseline (mean +/- SD 11 +/- 3 days) to 2 years after an acute myocardial infarction in 122 hypertensive (defined as a history of treated hypertension, baseline systolic blood pressure > or =140 or baseline diastolic blood pressure > or =90 mm Hg) and 334 nonhypertensive patients in the Survival and Ventricular Enlargement echocardiographic substudy. Compared with nonhypertensives, baseline heart size, defined as the sum of the average short- and long-axis LV cavity areas, was similar (70.1 +/- 11.9 vs 68.8 +/- 11.2 cm(2), p = 0.33 at end-diastole; 50.1 +/- 11.3 vs 48.8 +/- 10.8 cm(2), p = 0.31 at end-systole), but short-axis LV myocardial area (24.7 +/- 4.3 vs 25.7 +/- 5.0 cm(2), p = 0.043) and wall thickness (1.15 +/- 0.16 vs 1.21 +/- 0.17 cm, p = 0.004) at end-diastole were greater among hypertensives. The myocardial infarct segment lengths were similar in the 2 groups (p = 0.22). Although LV cavity areas increased significantly in the 2 groups from baseline to 2 years (p < or =0.001), the increase was significantly greater in hypertensives than in nonhypertensives (+5.6 +/- 11.5 vs +2.2 +/- 10.7 cm(2), p = 0.005 at end-diastole; +6.23 +/- 12.75 vs +2.94 +/- 11.4 cm(2), p = 0.012 at end-systole). There was no concomitant difference in the change in LV myocardial area or LV wall thickness between the 2 groups (p >0.30). After adjusting for known confounders, antecedent hypertension was associated with a doubling of the risk of LV dilation (50.8% vs 37.7%, odds ratio 2.09, 95% confidence interval 1.27 to 3.45, p = 0.004). This association was not modified by diabetes mellitus, myocardial infarct segment length, or captopril use (all p values for interaction >0.10). We conclude that antecedent hypertension is associated with subsequent LV dilation in patients after acute myocardial infarction with LV systolic dysfunction.

Homocysteine and cardiovascular disease: biological mechanisms, observational epidemiology, and the need for randomized trials

Basic research indicates that homocysteine causes endothelial dysfunction and damage, accelerates thrombin formation, inhibits native thrombolysis, promotes lipid peroxidation through free radical formation, and induces vascular smooth muscle proliferation and monocyte chemotaxis. Most, but not all, observational epidemiological studies indicate that individuals with higher homocysteine levels have increased risks of cardiovascular disease. The magnitude ranges from approximately 20% in prospective studies to approximately 80% in retrospective case-control studies. In all observational epidemiological studies, however, the amount of uncontrolled and uncontrollable confounding is as large as the postulated small to moderate effect size. Thus, the totality of evidence should include randomized trials of sufficient sample size and duration with clinical end points. Folic acid reduces levels of homocysteine, but at present, despite several plausible biological mechanisms and a large body of observational epidemiological data, it is unclear whether supplementation will reduce risks of cardiovascular disease. It is also unclear whether any benefit of folic acid is attributable to lowering homocysteine levels. The current evidence is necessary, but not sufficient to judge causality. Such judgments await the availability of data from large-scale randomized trials. The availability of such data would permit rational clinical decision-making for individual patients and policy decisions for the health of the general public.

Predictors of stroke in patients paced for sick sinus syndrome

OBJECTIVES

This study was an analysis of factors associated with stroke in a population of patients paced for sinus node dysfunction in a large prospective clinical trial (Mode Selection Trial [MOST]).

BACKGROUND

The effects of dual-chamber versus single-chamber ventricular pacing on subsequent stroke in patients with sinus node dysfunction are not known.

METHODS

A total of 2,010 patients with sinus node dysfunction were randomized to ventricular or dual-chamber pacing and followed for a median of 33.1 months.

RESULTS

The median participant age was 74 years. During 5,664 patient-years of follow-up, 90 strokes (11 hemorrhagic) occurred. By life-table analysis, the rate of stroke was 2.2% (95% confidence interval [CI] 1.6 to 2.9) at one year and 5.8% (95% CI 4.5 to 7.1) at four years. The incidence of stroke was not significantly different in dual-chamber (4%) as compared with ventricular-paced patients (4.9%) (hazard ratio [HR] 0.82, 95% CI 0.54 to 1.25, p = 0.36). Multivariable analysis demonstrated that significant predictors of stroke included prior stroke or transient ischemic attack, Caucasian race, hypertension, prior systemic embolism, and New York Heart Association functional class III or IV (p < 0.05); pacing mode remained non-significant after adjustment for these factors (p = 0.37). Clinically reported atrial fibrillation after implantation was a risk factor for stroke in this cohort after adjustment for other predictors of stroke (p = 0.042, HR 1.68 [95% CI 1.02 to 2.76]).

CONCLUSIONS

Clinical characteristics, but not mode of pacing, were associated with subsequent stroke in patients paced for sinus node dysfunction.

Prolonged QTc interval and risks of total and cardiovascular mortality and sudden death in the general population: a review and qualitative overview of the prospective cohort studies

BACKGROUND

In certain subgroups of patients, prolongation of the QTc interval may increase total and cardiovascular mortality due to life-threatening ventricular arrhythmias and sudden death. Nonetheless, whether modest prolongation of the QTc interval in the general population has clinical importance remains unclear.

METHODS

We conducted a literature search from 1990 forward to identify all published prospective cohort studies evaluating the association between prolonged QTc interval and risks of total and cardiovascular mortality as well as sudden death. We reviewed each of the studies individually and then conducted a qualitative overview.

RESULTS

The 7 prospective cohort studies identified included 36 031 individuals. There were 2677 (8.7%) individuals with prolonged QTc interval, defined as 440 milliseconds or greater. Whereas 1 study reported no association between prolonged QTc interval and mortality (relative risk, 1.02; 95% confidence interval, 0.70-1.49), the other 6 reported inconsistent associations overall as well as across subgroups defined by various characteristics including age, sex, and comorbidities. The reported associations for both cardiovascular mortality and sudden death were also inconsistent. In the overview, the only consistent findings were for the subgroup of patients with prior cardiovascular disease, in which relative risks ranged from 1.1 to 3.8 for total mortality, from 1.2 to 8.0 for cardiovascular mortality, and from 1.0 to 2.1 for sudden death. Further, in individuals without prior cardiovascular disease, associations were either absent or greatly attenuated; specifically, relative risks ranged from 0.9 to 1.6 for total mortality, from 1.2 to 1.7 for cardiovascular mortality, and from 1.3 to 2.4 for sudden death.

CONCLUSIONS

There was no consistent evidence for increased risks of total or cardiovascular mortality or of sudden death, except perhaps for patients with prior cardiovascular disease. In the general population, if QTc interval prolongation is associated with any increase in mortality, that risk is likely to be small and difficult to detect reliably.

High incidence of pacemaker syndrome in patients with sinus node dysfunction treated with ventricular-based pacing in the Mode Selection Trial (MOST)

OBJECTIVES

We evaluated the incidence, predictors, and treatment of pacemaker syndrome in patients with sinus node dysfunction treated with ventricular-based (VVIR) pacing in the Mode Selection Trial (MOST).

BACKGROUND

Pacemaker syndrome, or intolerance to VVIR pacing, consists of cardiovascular signs and symptoms induced by VVIR pacing.

METHODS

The definition of pacemaker syndrome required that a patient with single-chamber VVIR pacing develop either congestive signs and symptoms associated with retrograde conduction during VVIR pacing or a >or=20 mm Hg reduction of systolic blood pressure during VVIR pacing, associated with reproducible symptoms of weakness, lightheadedness, or syncope.

RESULTS

Of 996 patients randomized to VVIR pacing, 182 (18.3%) met criteria for pacemaker syndrome in follow-up. Pacemaker syndrome occurred early in most patients (13.8% at 6 months, 16.0% at 1 year, increasing to 19.7% at 4 years). Baseline univariate predictors of pacemaker syndrome included a lower sinus rate and higher programmed pacemaker rate. Previous heart failure, ejection fraction, and drop in systolic blood pressure with VVIR pacing at implantation did not predict the development of pacemaker syndrome. Post-implantation predictors of pacemaker syndrome were a higher percentage of paced beats, higher programmed low rate, and slower underlying spontaneous sinus rate. Quality of life decreased at the time of diagnosis of pacemaker syndrome and improved with reprogramming to atrial-based pacing.

CONCLUSIONS

Severe pacemaker syndrome developed in nearly 20% of VVIR-paced patients and improved with reprogramming to the dual-chamber pacing mode. Because prediction of pacemaker syndrome is difficult, the only way to prevent pacemaker syndrome is to implant atrial-based pacemakers in all patients.

Alcohol consumption and prognosis in patients with left ventricular systolic dysfunction after a myocardial infarction

OBJECTIVES

We assessed the influence of alcohol intake on the development of symptomatic heart failure (HF) in patients with left ventricular (LV) dysfunction after a myocardial infarction (MI).

BACKGROUND

In contrast to protection from coronary heart disease, alcohol consumption has been linked to cardiodepressant effects and has been considered contraindicated in patients with HF.

METHODS

The Survival And Ventricular Enlargement (SAVE) trial randomized 2231 patients with a LV ejection fraction (EF) <40% following MI to an angiotensin-converting enzyme inhibitor or placebo. Patients were classified as nondrinkers, light-to-moderate drinkers (1 to 10 drinks/week), or heavy drinkers (>10 drinks/week) based on alcohol consumption reported at baseline. The primary outcome was hospitalization for HF or need for an open-label angiotensin-converting enzyme inhibitor. Analyses were repeated using alcohol consumption reported three months after MI.

RESULTS

Nondrinkers were older and had more comorbidities than light-to-moderate and heavy drinkers. In univariate analyses, baseline light-to-moderate alcohol intake was associated with a lower incidence of HF compared with nondrinkers (hazard ratio [HR] 0.71; 95% confidence interval [CI] 0.57 to 0.87), whereas heavy drinking was not (HR 0.91; 95% CI 0.67 to 1.23). After adjustment for baseline differences, light-to-moderate baseline alcohol consumption no longer significantly influenced the development of HF (light-to-moderate drinkers HR 0.93; 95% CI 0.75 to 1.17; heavy drinkers HR 1.25; 95% CI 0.91 to 1.72). Alcohol consumption reported three months after the MI similarly did not modify the risk of adverse outcome.

CONCLUSIONS

In patients with LV dysfunction after an MI, light-to-moderate alcohol intake either at baseline or following MI did not alter the risk for the development of HF requiring hospitalization or an open-label angiotensin-converting enzyme inhibitor.