Prospective Randomized Study of Mode Switching in a Clinical Trial of Pacemaker Therapy for Sinus Node Dysfunction

INTRODUCTION

Atrial fibrillation (AF) is common in pacemaker patients with sinus node dysfunction (SND) and may result in rapid ventricular pacing (RVP) in the DDDR mode. Mode switching (MS) reduces RVP, but its clinical benefit in patients with SND is unknown.

METHODS AND RESULTS

Two hundred two patients in the Mode Selection Trial (MOST; 2,010-patient, 6-year trial of DDDR vs VVIR pacing in SND) randomized to DDDR pacemakers with atrial high-rate episode (AHRE) storage capabilities were subrandomized to MS ON (N = 96) or MS OFF (N = 106). Cardiovascular symptoms, quality of life (QOL), reprogramming due to RVP, death, stroke, and heart failure hospitalization (HFH) were compared between groups. The treatment groups were similar with regard to AF history (59% MS ON vs 57% MS OFF). AHREs occurred in 49% patients during median follow-up of 2.2 years. Median AHRE duration (in min; MS ON 116 vs MS OFF 58, P = 0.29), frequency AHREs/week (MS ON 3.5 vs MS OFF 6.4, P = 0.23), and time spent in AHRE (min/week) (MS ON 450, MS OFF 268) were similar. Reprogramming due to any RVP during AHREs occurred more in MS OFF vs MS ON (13.2% vs 3.1%, P = 0.011) and marginally more for symptomatic RVP (8.5% vs 2.1%, P = 0.062). Cardiovascular symptoms occurred in 93.6% MS ON vs 90.2% MS OFF (P = 0.38). Median number of symptoms reported per visit was similar (MS ON 1.3 vs MS OFF 1.5, P = 0.62). Median symptom frequency/severity, summed and averaged over visits, was similar (MS ON 4.3 vs MS OFF 4.5, P = 0.74). QOL was not different between groups. Death, stroke, and HFH were not different between groups.

CONCLUSION

MS reduces pacemaker reprogramming due to RVP during AHREs in a small number of patients but does not improve QOL or cardiovascular symptoms overall among patients with SND.

An update on clinical trials in pacing: is dual chamber pacing better?

PURPOSE OF REVIEW

As pacemaker technology has increased in complexity and now offers a variety of additional capabilities, there is uncertainty as to which pacing mode offers more benefit-dual-chamber or single-chamber.

RECENT FINDINGS

Two large-scale randomized trials, the Canadian Trial of Physiologic Pacing and the Mode Selection Trial, demonstrated that dual-chamber pacing does not reduce the incidence of stroke or improve survival when compared with ventricular pacing. However, dual-chamber pacing does reduce the incidence of atrial fibrillation and in patients with sinus node dysfunction, reduces heart failure symptoms when compared with ventricular pacing. The modest results of these trials were unexpected when viewed in the context of the very favorable retrospective studies.

SUMMARY

A rethinking of the physiology of cardiac pacing has led to the concept that although atrioventricular synchrony supports an improvement in cardiac output and ventricular pressures, these favorable hemodynamics may be attenuated by ventricular dyssynchrony from right ventricular apical pacing. In patients with a reduced ejection fraction, this dyssynchrony may be especially detrimental. Two trials (DANPACE and SAVE-PACE) are currently underway that will clarify the clinical significance of reducing forced ventricular desynchronization. The results of these trials may direct pacemaker physicians away from the right ventricular apical lead toward a new imperative of atrioventricular and right ventricular-left ventricular synchrony.

Predictors and Clinical Impact of Atrial Fibrillation After Pacemaker Implantation in Elderly Patients Treated with Dual Chamber Versus Ventricular Pacing

The Pacemaker Selection in the Elderly (PASE) trial was a prospective, multicenter, single blind, randomized comparison of single chamber, rate adaptive, ventricular pacing (VVIR) with dual chamber, rate adaptive pacing (DDDR) in 407 patients aged > or =65 years(mean 76 +/- 7 years, 60% male)with standard bradycardia indications for dual chamber pacemaker implantation. The incidence, predictors, and clinical consequences of atrial fibrillation (AF) developing after pacemaker implantation in the PASE trial were studied prospectively. During a median follow-up of 18 months, AF developed in 73 (18%) patients. Kaplan-Meier estimated cumulative incidences of AF in patients with sinus node dysfunction (n=176) at 18 months were 28% in the VVIR and 16% in the DDDR groups (P=0.08). After adjustment for other clinical variables using a Cox multivariate regression model, randomization to VVIR compared with DDDR pacing mode among patients with sinus node dysfunction was independently associated with a 2.6-fold increased relative risk (RR) of developing AF after pacemaker implantation (P=0.01). Other independent clinical risk factors for development of postimplant AF included a preimplant history of hypertension (P=0.02) or supraventricular tachyarrhythmias(P<0.04). Patients who developed AF had similar health related quality of life scores and cardiovascular functional status after 18 months of pacing as patients who remained free of AF. The RR of death, stroke, or heart failure hospitalization was not increased in patients who developed AF. Thus, in the elderly patients with sinus node dysfunction requiring permanent pacing, DDDR pacing mode protected against the development of AF. However, development of AF after pacemaker implantation in this population was not associated with a significant impact on quality-of-life, functional status, or other clinical endpoints during 18 months of follow-up.

Complications arising after implantation of DDD pacemakers: the MOST experience

The purpose of this study was to characterize the incidence, time course, frequency, and spectrum of acute and chronic complications arising from dual-chamber pacemaker implantation. This information may serve as a benchmark when comparing complication rates for dual-chamber pacemaker implantation with those for biventricular pacemaker implantation.

Have the results of randomized clinical trials of pacing altered the practice of cardiac pacing?

Randomized clinical trials are the gold standard for the evaluation of new therapies. However, in the early years of pacing, the observational benefits were so great and the lifesaving benefits to patients so readily obvious that randomized trials were not necessary to prove benefit. As the technology has matured, advances have become more evolutionary than revolutionary, and observational analyses are unable to provide convincing evidence of small-to-moderate benefits. Thus, randomized trials of sufficient sample size are necessary to reliably assess the small-to-moderate effects of advances such as dual-chamber pacing, rate modulation, and mode switching. It is only during the last decade, however, that the evidence base for pacing with regard to randomized trials has begun to emerge. It is unclear whether the emerging results of these clinical trials have affected the clinical practice of pacing.

Adverse effect of ventricular pacing on heart failure and atrial fibrillation among patients with normal baseline QRS duration in a clinical trial of pacemaker therapy for sinus node dysfunction

BACKGROUND

Dual-chamber (DDDR) pacing preserves AV synchrony and may reduce heart failure (HF) and atrial fibrillation (AF) compared with ventricular (VVIR) pacing in sinus node dysfunction (SND). However, DDDR pacing often results in prolonged QRS durations (QRSd) as the result of right ventricular stimulation, and ventricular desynchronization may result. The effect of pacing-induced ventricular desynchronization in patients with normal baseline QRSd is unknown.

METHODS AND RESULTS

Baseline QRSd was obtained from 12-lead ECGs before pacemaker implantation in MOST, a 2010-patient, 6-year, randomized trial of DDDR versus VVIR pacing in SND. Cumulative percent ventricular paced (Cum%VP) was determined from stored pacemaker data. Baseline QRSd <120 ms was observed in 1339 patients (707 DDDR, 632 VVIR). Cum%VP was greater in DDDR versus VVIR (90% versus 58%, P=0.001). Cox models demonstrated that the time-dependent covariate Cum%VP was a strong predictor of HF hospitalization in DDDR (hazard ratio [HR], 2.99 [95% CI, 1.15 to 7.75] for Cum%VP >40%) and VVIR (HR 2.56 [95% CI, 1.48 to 4.43] for Cum%VP >80%). The risk of AF increased linearly with Cum%VP from 0% to 85% in both groups (DDDR, HR 1.36 [95% CI, 1.09, 1.69]; VVIR, HR 1.21 [95% CI 1.02, 1.43], for each 25% increase in Cum%VP). Model results were unaffected by adjustment for known baseline predictors of HF hospitalization and AF.

CONCLUSIONS

Ventricular desynchronization imposed by ventricular pacing even when AV synchrony is preserved increases the risk of HF hospitalization and AF in SND with normal baseline QRSd.

Pacemaker mode selection: the evidence from randomized trials

The evidence base for pacing, specifically with regards to outcome-based randomized trials, is only beginning to emerge. At present, the guidelines for pacing in sinus node dysfunction (SND), atrioventricular block (AVB), and vasovagal syncope are largely based on observational, not randomized studies. The findings from observational studies that physiological pacing was associated with reduced mortality, fewer strokes, less heart failure, and less AF when compared with ventricular pacing, were not uniformly supported by the early randomized trials of a relatively small sample size. Thus, it has become increasingly clear that large scale randomized trials are necessary to measure reliably the benefit, if any, of progressively more expensive and complex pacemakers. To provide reliable answers to these important questions, three large multicenter randomized trials in Canada, the United Kingdom, and the United States have been designed and conducted. The present review analyzed the results of completed randomized trials on pacemaker mode selection. To date, > 6,000 patients requiring permanent pacing to prevent bradycardia have been randomized; among these, dual chamber pacing did not prevent stroke or improve survival when compared with ventricular pacing. However, dual chamber pacing led to a moderate reduction of incident and chronic AF, reduced symptoms of heart failure in patients with SND, prevented pacemaker syndrome, and modestly improved quality-of-life. Further, a 5-10% reduction in mortality by atrial-based pacing cannot be excluded based on the results of the analyzed trials. The availability of data from ongoing randomized trials and their meta analysis should complete the totality of evidence during the next several years.

Atrial high rate episodes detected by pacemaker diagnostics predict death and stroke: report of the Atrial Diagnostics Ancillary Study of the MOde Selection Trial (MOST)

BACKGROUND

Some current pacing systems can automatically detect and record atrial tachyarrhythmias that may be asymptomatic. We prospectively studied a 312-patient (pt) subgroup of MOST (MOde Selection Trial), a 2010-patient, 6-year randomized trial of DDDR versus VVIR pacing in sinus node dysfunction (SND). The purpose of the study was to correlate atrial high rate events (AHREs) detected by pacemaker diagnostics with clinical outcomes.

METHODS AND RESULTS

Pacemakers were programmed to log an AHRE when the atrial rate was >220 bpm for 10 consecutive beats. Analysis was confined to patients with at least 1 AHRE duration exceeding 5 minutes. The 312 patients were median age 74 years, 55% female, and 60% had a history of SVT. 160 of 312 (51.3%) patients enrolled had at least 1 AHRE >5 minutes duration over median follow-up of 27 months. Cox proportional hazards analysis assessed the relationship of AHREs with clinical events, adjusting for prognostic variables and baseline covariates. The presence of any AHRE was an independent predictor of the following: total mortality (hazard ratio AHRE versus no AHRE and 95% confidence intervals=2.48 [1.25, 4.91], P=0.0092); death or nonfatal stroke (2.79 [1.51, 5.15], P=0.0011); and atrial fibrillation (5.93 [2.88, 12.2], P=0.0001). There was no significant effect of pacing mode on the presence or absence of AHREs.

CONCLUSIONS

AHRE detected by pacemakers in patients with SND identify patients that are more than twice as likely to die or have a stroke, and 6 times as likely to develop atrial fibrillation as similar patients without AHRE.

Brain natriuretic peptide and HIV-related cardiomyopathy

The brain natriuretic peptide (BNP) assay is a new, relatively inexpensive, and simple test that has the potential to be an early, cost-effective, and reliable marker for HIV-related cardiomyopathy. We report 1 case of HIV-related cardiomyopathy and 10 cases of of HIV infection with unknown heart disease in which we measured BNP levels and performed echocardiography. We found a significant inverse relationship between BNP and left ventricular function in these patients. Further basic and epidemiologic research on BNP measurement for the detection of HIV-related cardiomyopathy is needed to support these findings, which if confirmed, could have important clinical and public health implications.

Thiazolidinediones could improve endothelial dysfunction and risk of premature coronary heart disease in HIV-infected patients

The use of Human Immunodeficiency Virus (HIV) protease inhibitors as part of the Highly Active Antiretroviral Therapy (HAART) is associated with atherogenic dyslipoproteinemia, insulin resistance, hypertension and endothelial dysfunction, all of which contribute to premature coronary heart disease. These abnormalities appear to be associated with an increase in cardiovascular events in HIV-infected patients. Beneficial metabolic effects of anti-diabetic agents used in HIV-infected patients have been reported. The thiazolidinediones (TZDs), a new group of antidiabetic drugs, may modulate the proliferative and inflammatory cascades involved in atherosclerosis. Thus, an increasing totality of evidence suggests that TZDs may represent a unique and powerful research tool to find a common denominator underlying the pathophysiology and treatment of the metabolic cardiovascular risk factors associated with HIV infection.

Health values before and after pacemaker implantation

BACKGROUND

Health value or utility is the abstracted magnitude of a person's preference for quality and quantity of life. It reflects how much lifetime with the patient's current health condition a patient is willing to exchange for a life in excellent health. Health values are used in cost-effectiveness analysis as a means of calculating quality-adjusted years of life.

OBJECTIVE

This study assessed the health values of elderly patients before and after pacemaker implantation.

METHODS

We prospectively examined 398 patients from the Pacemaker Selection in the Elderly study, in which patients were randomized to either VVIR or DDDR mode. Health values were estimated with the time tradeoff method before implantation and at 3, 9, and 18 months after implantation.

RESULTS

The mean age of patients was 76 +/- 6 years; 234 patients (59%) were male. At baseline, patients were, on average, willing to exchange 5 years of current health for approximately 4 years in perfect health (value 0.76 +/- 0.06). There was no difference in baseline health values with implant diagnosis (sinus node dysfunction n = 172, 0.72, atrioventricular block n = 227, 0.75, other diagnoses n = 39, 0.78, P = not significant). The overall improvement in health values at 3 months after pacemaker implantation was 0.165 +/- 0.4 (P =.0001). The improvement in health values was independent of pacing mode (P =.6). The time tradeoff score was modestly correlated with other measurements of health-related quality of life. The change in time tradeoff score with time was not influenced by demographic characteristics such as age and sex, diagnoses, pacing mode, employment status, or history of angina. Patients with a lower functional class at enrollment (III or IV on the Specific Activity Scale) demonstrated an absolute improvement of 23% in their health values, whereas patients in class I or II improved only by 12%, (P =.03).

CONCLUSIONS

Permanent pacemaker implantation for standard indications improves health values and descriptive health status measures. The values reported here may be used as a means of calculating the cost-effectiveness of different pacing modalities.

Ventricular remodeling does not accompany the development of heart failure in diabetic patients after myocardial infarction

BACKGROUND

Diabetic patients are at increased risk for heart failure (HF) and other adverse events after myocardial infarction (MI). Left ventricular (LV) enlargement after MI is also associated with the same increased risk. We used data from the Survival and Ventricular Enlargement (SAVE) echocardiographic substudy to test the hypothesis that diabetes was associated with increased LV enlargement after MI.

METHODS AND RESULTS

Four hundred twelve nondiabetic and 100 diabetic patients underwent echocardiographic assessment at baseline and 3 months, 1 year, and 2 years after MI. HF developed in 30% of diabetic and 17% of nondiabetic patients during follow-up (P<0.001). Baseline LV diastolic size, ejection fraction, and infarct segment length were similar between diabetic and nondiabetic patients. Diabetic patients demonstrated less LV enlargement between baseline and 2 years than nondiabetic patients (0.9+/-11.1 cm2 versus 3.8+/-10.9 cm2, P=0.047). In patients who developed HF, LV diastolic dilatation (10.0+/-12.4 cm2 versus 3.7+/-13.1 cm2, P=0.06) and systolic dilatation (4.6+/-11.8 versus 0.91+/-12.1, P=0.017) were greater in nondiabetic than in diabetic patients. LV dilatation between baseline and 2 years was a predictor of HF in nondiabetic patients, but not in diabetic patients, even after excluding patients with recurrent MI and adjusting for history of hypertension, prior MI, age, treatment group, and smoking. Diabetes modified the relationship between ventricular enlargement and the risk of HF (P=0.011).

CONCLUSIONS

The increased incidence of HF after MI in diabetic patients is not explained by a greater propensity for LV remodeling.

Plasma levels of brain natriuretic peptide: a potential marker for HIV-related cardiomyopathy

One of the most common and life-threatening cardiovascular complications of HIV-infection is severe global left ventricular dysfunction due to primary heart muscle disease. At present, there is no single, cost-effective and reliable method of identifying the highly prevalent HIV-related cardiac dysfunction. Nonetheless, growing evidence supports the hypothesis that brain natriuretic peptide measurement has the potential to detect patients who develop HIV-related cardiomyopathy. If true, this hypothesis would have important clinical and public health implications.

Ventricular pacing or dual-chamber pacing for sinus-node dysfunction

BACKGROUND

Dual-chamber (atrioventricular) and single-chamber (ventricular) pacing are alternative treatment approaches for sinus-node dysfunction that causes clinically significant bradycardia. However, it is unknown which type of pacing results in the better outcome.

METHODS

We randomly assigned a total of 2010 patients with sinus-node dysfunction to dual-chamber pacing (1014 patients) or ventricular pacing (996 patients) and followed them for a median of 33.1 months. The primary end point was death from any cause or nonfatal stroke. Secondary end points included the composite of death, stroke, or hospitalization for heart failure; atrial fibrillation; heart-failure score; the pacemaker syndrome; and the quality of life.

RESULTS

The incidence of the primary end point did not differ significantly between the dual-chamber group (21.5 percent) and the ventricular-paced group (23.0 percent, P=0.48). In patients assigned to dual-chamber pacing, the risk of atrial fibrillation was lower (hazard ratio, 0.79; 95 percent confidence interval, 0.66 to 0.94; P=0.008), and heart-failure scores were better (P<0.001). The differences in the rates of hospitalization for heart failure and of death, stroke, or hospitalization for heart failure were not significant in unadjusted analyses but became marginally significant in adjusted analyses. Dual-chamber pacing resulted in a small but measurable increase in the quality of life, as compared with ventricular pacing.

CONCLUSIONS

In sinus-node dysfunction, dual-chamber pacing does not improve stroke-free survival, as compared with ventricular pacing. However, dual-chamber pacing reduces the risk of atrial fibrillation, reduces signs and symptoms of heart failure, and slightly improves the quality of life. Overall, dual-chamber pacing offers significant improvement as compared with ventricular pacing.

Right ventricular dysfunction and risk of heart failure and mortality after myocardial infarction

OBJECTIVES

The aim of this study was to determine the prognostic value of right ventricular (RV) function in patients after a myocardial infarction (MI).

BACKGROUND

Right ventricular function has been shown to predict exercise capacity, autonomic imbalance and survival in patients with advanced heart failure (HF).

METHODS

Two-dimensional echocardiograms were obtained in 416 patients with left ventricular (LV) dysfunction (ejection fraction [LVEF] < or = 40%) from the Survival And Ventricular Enlargement (SAVE) echocardiographic substudy (mean 11.1 +/- 3.2 days post infarction). Right ventricular function from the apical four-chamber view, assessed as the percent change in the cavity area from end diastole to end systole (fractional area change [FAC]), was related to clinical outcome.

RESULTS

Right ventricular function correlated only weakly with the LVEF (r = 0.12, p = 0.013). On univariate analyses, the RV FAC was a predictor of mortality, cardiovascular mortality and HF (p < 0.0001 for all) but not recurrent MI. After adjusting for age, gender, diabetes mellitus, hypertension, previous MI, LVEF, infarct size, cigarette smoking and treatment assignment, RV function remained an independent predictor of total mortality, cardiovascular mortality and HF. Each 5% decrease in the RV FAC was associated with a 16% increased odds of cardiovascular mortality (95% confidence interval 4.3% to 29.2%; p = 0.006).

CONCLUSIONS

Right ventricular function is an independent predictor of death and the development of HF in patients with LV dysfunction after MI.

Outcome and cost-effectiveness of cardiopulmonary resuscitation after in-hospital cardiac arrest in octogenarians

CONTEXT

Octogenarians are the fastest growing segment of the population and little is known about the results of cardiopulmonary resuscitation (CPR) after in-hospital cardiac arrest in this population.

OBJECTIVE

We sought to investigate the clinical benefit and cost-effectiveness of CPR after in-hospital cardiac arrest in octogenarians.

MAIN OUTCOME MEASURE

Years of life saved.

DESIGN

Effectiveness data were obtained from a review of 91,372 hospital discharges from January 1st, 1993 until June 30th, 1996. Cardiac arrest was reported in 956 patients. The study group consisted of 474 patients > or = 80 years old. CPR costs included equipment and training, physician and nursing time and medications. Post-CPR expenses included in-hospital true cost, repeat hospitalizations, physician office visits, nursing home, rehabilitation, and chronic care hospital costs. Life expectancy of the patients who were still alive at the end of the study was estimated from census data. A utility of 0.8 was used to calculate quality-adjusted-life years saved (QALYS). We used a societal perspective for analysis.

RESULTS

The study population was 86 +/- 4.8 years old (range 80-103), and 42% were male. Fifty-four patients (11%) were discharged alive, 35 to a chronic care facility and 19 to their home. Assuming that a cardiac arrest without CPR has 100% mortality, 12 octogenarians required treatment with CPR in order to save one life to hospital discharge. Similarly, 29 octogenarian patients with cardiac arrest have to be treated with CPR to net one long-term survivor (mean survival 21 months, with a range from 9 to 48 months). The cost-effectiveness ratio, after estimating the life expectancy of octogenarian survivors, was USD 50,412 per year of life saved, and USD 63,015 per QALYS. However, a utility of 0.5 yielded a cost of USD 100,825 per QALYS.

CONCLUSION

In comparison with other life-saving strategies, CPR in octogenarians is effective. The favorable cost-effectiveness ratio is highly dependent on the patients' preference for quality rather than quantity of life, as expressed by the utility assumptions.

Effect of cigar smoking on endothelium-dependent brachial artery dilation in healthy young adults

BACKGROUND

Cigar smoking has become a quickly growing trend among teenagers, women, and young adults. The objective was to explore whether cigar smoking affects flow-mediated vasodilation in healthy, non-smoking young adults.

METHODS

This was a prospective randomized trial with open design. It was performed in a cardiology teaching program in a private community hospital that serves as a major referral center within the greater Miami area. Apparently healthy, non-smoking young adult cardiology trainees and staff between the ages of 20 and 45 years were randomly assigned to a cigar smoking group (n = 15) or a control group (n = 14). The main outcome measures were the difference in percent diameter increase in the brachial artery after reactive hyperemia and sublingual nitroglycerin between members of the cigar smoking and control groups at baseline, measured after cigar smoking, and at 5 hours.

RESULTS

Twenty-nine participants were randomized. Percent diameter increase in the brachial artery was measured with the use of high-resolution ultrasonography. Baseline percent diameter increase after reactive hyperemia and sublingual nitroglycerin was similar in both groups (6.2% vs 6.7%, P = .4 and 22% vs 23%, P = .5, respectively). We observed a 2.5% increase in brachial artery diameter with hyperemia after cigar smoking compared with a 9.4% increase in the control group, P = .045. Values after nitroglycerin were similar between groups, P = .2. Between-group analysis showed no significant difference in percent dilation after reactive hyperemia at 5 hours, P = .4, but a significant difference was seen after sublingual nitroglycerin, P = .02.

CONCLUSIONS

These data are compatible with the possibility that cigar smoking may have an acute effect on endothelium-dependent, flow-mediated brachial artery dilation and do not support the possibility of an immediate effect on endothelium-independent vasodilation. Taken together, these results suggest that cigars are not an innocuous alternative to cigarette smoking.

The mode selection trial (MOST) in sinus node dysfunction: design, rationale, and baseline characteristics of the first 1000 patients

BACKGROUND

More than 200,000 permanent pacemakers will be implanted in the United States in 2000 at a cost of more than $2 billion. Sick sinus syndrome (SSS) will likely account for approximately half of all cases necessitating implantation. Pacemaker technology permits the selection of ventricular (single-chamber) or dual-chamber devices. However, clinical and outcomes data are inadequate to support a clear recommendation that one or the other type of device be used.

METHODS

The Mode Selection Trial (MOST) is a single-blind study supported by the National Heart, Lung, and Blood Institute designed to enroll 2000 patients with SSS. All patients will receive a DDDR pacemaker programmed to VVIR or DDDR before implantation. The average time of follow-up will be 3 years. MOST has a >90% power to detect a 25% reduction in the primary end point-nonfatal stroke or total (all cause) mortality-in the DDDR-treated group. Secondary end points will include health-related quality of life and cost effectiveness, atrial fibrillation, and development of pacemaker syndrome. Prespecified subgroups for analysis will include women and the elderly. Enrollment was completed in October 1999, with a total of 2010 patients.

RESULTS

The median age of the first 1000 enrolled patients is 74 years, with 25% of patients 80 years or older. Women comprise 49%, and 17% are nonwhite, predominantly black (13%). Before pacemaker implantation, 22% of patients reported a history of congestive heart failure, 11% coronary angioplasty, and 25% coronary bypass surgery. Supraventricular tachycardia including atrial fibrillation was present in 53% of patients. A prior stroke was reported by 12%. Antiarrhythmic therapy was in use in 18% of patients.

CONCLUSIONS

MOST will fill the clinical need for carefully designed prospective studies to define the benefits of dual-chamber versus single-chamber ventricular pacing in patients with SSS. The MOST population is typical of the overall pacemaker population in the United States. Thus the final results of MOST should be clinically generalizable.

Clinical characteristics of patients intolerant to VVIR pacing

The incidence and clinical predictors of the development of intolerance to VVIR pacing have not been extensively studied in prospective long-term randomized trials comparing different pacing modes. The frequency and clinical factors predicting intolerance to ventricular pacing are controversial. The Pacemaker Selection in the Elderly (PASE) Trial enrolled 407 patients aged >/=65 years in a 30-month, single-blind, randomized, controlled comparison of quality of life and clinical outcomes with ventricular pacing and dual-chamber pacing in patients undergoing dual-chamber pacemaker implantation for standard clinically accepted indications. We reviewed the clinical, hemodynamic, and electrophysiologic variables at the time of pacemaker implantation in 204 patients enrolled in the PASE trial and randomized to the VVIR mode, some of whom subsequently required crossover (reprogramming) to DDDR pacing. During a median follow-up of 555 days, 53 patients (26%) crossed over from VVIR to DDDR pacing. A decrease in systolic blood pressure during ventricular pacing at the time of pacemaker implantation (p = 0.001), use of beta blockers at the time of randomization (p = 0.01), and nonischemic cardiomyopathy (p = 0.04) were the only variables that predicted crossover in the Cox multivariate regression model. After reprogramming to the dual-chamber mode, patients showed improvement in all aspects of quality of life, with significant improvements in physical and emotional role. The high incidence of crossover from VVIR to DDDR pacing along with significant improvements in quality of life after crossover to DDDR pacing strongly favors dual-chamber pacing compared with single-chamber ventricular pacing in elderly patients requiring permanent pacing.

Update in internal medicine

More than 500,000 new medical articles are published every year and available time to keep updated is scarcer every day. Nowadays, the task of selecting useful, consistent, and relevant information for clinicians is a priority in many major medical journals. This review has the aim of gathering the results of the most important findings in clinical medicine in the last few years. It is focused on results from randomized clinical trials and well-designed observational research. Findings were included preferentially if they showed solid results, and we avoided as much as possible including only preliminary data, or results that included only non-clinical outcomes. Some of the most relevant findings reported here include the significant benefit of statins in patients with coronary artery disease even with mean cholesterol level. It also provides a substantial review of the most significant trials assessing the effectiveness of IIb/IIIa receptor blockers. In gastroenterology many advances have been made in the H. pylori eradication, and the finding that the cure of H. pylori infection may be followed by gastroesophageal reflux disease. Some new antivirals have shown encouraging results in patients with chronic hepatitis. In the infectious disease arena, the late breaking trials in anti-retroviral disease are discussed, as well as the new trends regarding antibiotic resistance. This review approaches also the role of leukotriene modifiers in the treatment of asthma and discusses the benefit of using methylprednisolone in patients with adult respiratory distress syndrome, among many other advances in internal medicine.

Beneficial effects of an open artery on left ventricular remodeling after myocardial infarction

During the last 2 decades researchers have developed a clearer understanding of the pathophysiology of acute myocardial infarction (AMI). The use of thrombolysis and coronary angioplasty early in the course of AMI salvages myocardium and preserves left ventricular function, which results in improved survival rates. Late reperfusion after AMI, however, may provide beneficial effects on long-term prognosis, especially owing to attenuation of left ventricular remodeling. This article reviews the evidence of the benefits of an open infarct-related artery on left ventricular remodeling after AMI.

Age-related differences in management of heart disease: a study of cardiac medication use in an older cohort. Pacemaker Selection in the Elderly (PASE) Investigators

BACKGROUND

Previous studies have suggested suboptimal use of cardiac medications for secondary prevention after myocardial infarction (MI) and atrial fibrillation (AF), especially among older people.

OBJECTIVE

To determine whether patients older than 75 years are less likely than those aged 65 to 74 to be prescribed medications with evidence-based indications, including angiotensin-converting enzyme (ACE) inhibitors for left ventricular dysfunction (LVD) and/or diabetes mellitus (DM), aspirin and/or beta-blockers for those with a history of MI, and warfarin for chronic AF.

DESIGN

A retrospective cohort study.

SETTING

Twenty-nine hospitals, predominantly tertiary-care institutions.

PARTICIPANTS

A total of 407 patients randomized to ventricular or dual-chamber pacing from February 26, 1993, to September 30, 1994, in the Pacemaker Selection in the Elderly (PASE) trial.

MEASUREMENTS

A review of the patient's medical history and a physical exam at study enrollment, three follow-up timepoints, and a study closeout.

RESULTS

Patients older than 75 years with LVD and/or DM were less likely to be prescribed ACE inhibitors (OR = .56 (0.31-1.00)); patients older than 75 with a history of MI were less likely to be taking aspirin (OR = .43 (0.19-.95)), and patients older than 75 with AF were less likely to be prescribed warfarin (OR = .18 (0.05-.61)). Patients older than 75 years of age with any or all of the conditions studied were less likely to be prescribed indicated medications than those ages 65 to 74 (OR = .35 (0.18-.70)), after controlling for between-group differences in comorbidity, gender, and number of noncardiac medications.

CONCLUSION

Older age is a significant independent negative correlate of evidence-based cardiac medication use in this cohort. Causes for this finding need to be explored.

[Ventricular geometry and heart failure]

In the last years there has been an appreciation of the importance of left ventricular geometry. After a period, in the sixties and seventies, that the interest was focused on cardiac physiology and the left ventricular geometry role about this subject, new studies are available on clinical significance of normal or distorted left ventricular shape. New assessment methods of ventricular geometry have been described. The use of simple measurements to assess ventricular geometry has allowed to know the clinical value of the shape distortion in patients with heart failure. The suspicion that left ventricular shape change to sphericity has prognosis value, has raised the interest about this subject. Whether distortion of left ventricular shape is an even better parameter than cardiac function indices normally used is under consideration. Moreover, new surgical therapies have been developed in an attempt to improve the ventricular geometry and to get better clinical prognosis in patients with heart failure.

Ejection fraction by radionuclide ventriculography and contrast left ventriculogram. A tale of two techniques. SAVE Investigators. Survival and Ventricular Enlargement

OBJECTIVES

We assessed the abilities of two methods to measure ejection fraction (EF)-radionuclide ventriculography (RVG) and contrast left ventriculography (Cath-EFa) to predict cardiovascular events.

BACKGROUND

Both RVG and Cath-EFa are commonly used methods to measure left ventricular performance and assess prognosis. Their comparative abilities to predict clinical events have not been reported.

METHODS

Both RVG EF and Cath-EFa were measured within 16 days of myocardial infarction (MI) in 688 patients. The results were divided into terciles. Prognosis by terciles was assessed for each technique. A multivariate analysis was performed to determine which EF measurement was a better predictor of prognosis.

RESULTS

Average RVG-EF was 32%+/-7, while Cath-EFa was 42%+/-10. Both RVG and Cath-EFa were poorly correlated (R=0.42). Event rate declined across terciles with increasing EF for both techniques (events in lowest to highest tercile of Cath-EFa 40.7%, 25.9%, 11.6%, p < 0.001; and RVG-EF 39.9%, 26.1%, 15.6%, p < 0.001). There was concordance of terciles in 303 of 688 patients (44%). When patients in the highest RVG terciles were in the highest Cath-EFa tercile, the event rate was 7%. However, when patients in the highest RVG terciles were in the lowest Cath-EFa tercile, the event rate was 19%. Both Cath-EFa (p < 0.001) and RVG-EF (p < 0.001) were independent predictors of cardiovascular events.

CONCLUSIONS

Ejection fraction measured by RVG or during catheterization is a valuable tool in the risk stratification of postinfarct patients. When disagreement is present between clinical impression and measurement by either method, the use of an alternative measurement is warranted and complementary.

Increased prevalence of significant tricuspid regurgitation in patients with transvenous pacemakers leads

Transvenous pacemaker leads are associated with an increased prevalence of tricuspid regurgitation. This hemodynamic derangement should be considered as part of the clinical cost and complications of permanent pacemaker implantation.

[Interpretation of negative clinical trials]

Randomized clinical trials without statistically significant differences between treatment groups may provide useful information for clinicians. However, negative trials must be interpreted cautiously, since the absence of evidence of treatment effect is not the same as evidence of absence of treatment effect. Before the reader of a negative article can conclude that one intervention was not better than the other, the potential causes of a negative study should be explored. The objective of this manuscript is to critically describe some of the most common methodological problems that can explain the lack of difference between studied groups in randomized clinical trials.

Complications of dual chamber pacemaker implantation in the elderly. Pacemaker Selection in the Elderly (PASE) Investigators

Pacemakers are frequently implanted, yet accurate prospective data on implant complications are limited. Elderly patients may be at increased risk of implant complications and are increasingly being referred for pacemaker implantation. The purpose of the present analysis was to define the incidence and possible predictors of serious complications of dual chamber permanent pacemaker implantation in the elderly. Therefore, we sought to prospectively identify the incidence and predictors of pacemaker implant complications in a large multicenter trial involving patients receiving a dual chamber pacemaker. The Pacemaker Selection in the Elderly (PASE) study was a prospective trial designed to evaluate quality of life in dual chamber pacemaker recipients age 65 years or older randomized to DDDR versus VVIR programming. In addition to being age 65 years or older, patients enrolled in this study were in normal sinus rhythm, and had standard indications for permanent pacemaker implantation. All patients received dual chamber pacemakers and were randomized to DDDR versus VVIR pacing. Pacemaker implant complications were collected on standardized forms which were completed at pacemaker implantation and during follow-up appointments. In this study of 407 patients, there were 26 complications occurring in 25 patients (6.1%). The most frequent complication was lead dislodgment which occurred in 9 patients. This was followed by pneumothorax (8 patients) and cardiac perforations (4 patients). In 18 patients (4.4%) repeat surgical procedures (including chest tubes) were required. Complications were noted prior to discharge in only 18 patients. There were no significant predictors of overall complications. Pneumothorax was more frequent in patients > or = 75 years old, and was observed only in patients with subclavian venous access. In conclusion, complications from pacemaker implantation in the elderly are seen in 6.1% of patients and 4.4% of patients require a repeat surgical procedure. Other than advanced age and lower weight predicting for pneumothorax, there are no significant clinical predictors of complications.

Quality of life and clinical outcomes in elderly patients treated with ventricular pacing as compared with dual-chamber pacing. Pacemaker Selection in the Elderly Investigators

BACKGROUND

Standard clinical practice permits the use of either single-chamber ventricular pacemakers or dual-chamber pacemakers for most patients who require cardiac pacing. Ventricular pacemakers are less expensive, but dual-chamber pacemakers are believed to be more physiologic. However, it is not known whether either type of pacemaker results in superior clinical outcomes.

METHODS

The Pacemaker Selection in the Elderly study was a 30-month, single-blind, randomized, controlled comparison of ventricular pacing and dual-chamber pacing in 407 patients 65 years of age or older in 29 centers. Patients received a dual-chamber pacemaker that had been randomly programmed to either ventricular pacing or dual-chamber pacing. The primary end point was health-related quality of life as measured by the 36-item Medical Outcomes Study Short-Form General Health Survey.

RESULT

The average age of the patients was 76 years (range, 65 to 96), and 60 percent were men. Quality of life improved significantly after pacemaker implantation (P<0.001), but there were no differences between the two pacing modes in either the quality of life or prespecified clinical outcomes (including cardiovascular events or death). However, 53 patients assigned to ventricular pacing (26 percent) were crossed over to dual-chamber pacing because of symptoms related to the pacemaker syndrome. Patients with sinus-node dysfunction, but not those with atrioventricular block, had moderately better quality of life and cardiovascular functional status with dual-chamber pacing than with ventricular pacing. Trends of borderline statistical significance in clinical end points favoring dual-chamber pacing were observed in patients with sinus-node dysfunction, but not in those with atrioventricular block.

CONCLUSION

The implantation of a permanent pacemaker improves health-related quality of life. However, the quality-of-life benefits associated with dual-chamber pacing as compared with ventricular pacing are observed principally in the subgroup of patients with sinus-node dysfunction.

Absence of a deleterious effect of calcium channel blockers in patients with left ventricular dysfunction after myocardial infarction: The SAVE Study Experience. SAVE Investigators. Survival and Ventricular Enlargement

BACKGROUND

As a result of randomized controlled trials with calcium channel blockers after myocardial infarction, concern has developed that these agents are associated with an increased risk of cardiovascular events, particularly in the presence of left ventricular dysfunction.

METHODS

To test the hypothesis that calcium channel blockers increase cardiovascular events in such patients, the incidence of all-cause mortality, cardiovascular death, severe heart failure, and recurrent infarction was examined in 940 patients taking calcium channel blockers and 1180 not taking them 24 hours before randomization to placebo or captopril in the Survival and Ventricular Enlargement (SAVE) Trial. All patients had an ejection fraction < or =40%. Relative risks for calcium channel blocker users versus nonusers and the 95% confidence intervals were computed with univariate and multivariate Cox regressions. Adjustments were made for differences in baseline covariates.

RESULTS

For all causes of mortality, the relative risk for calcium channel blocker users versus nonusers was 0.96, with the 95% confidence interval of 0.78 to 1.17. In the SAVE placebo and captopril groups, the relative risks for the development of severe heart failure among the calcium channel block users versus nonusers were 0.95 and 1.23, with the 95% confidence interval of 0.72 to 1.25 and 0.88 to 1.71, respectively. A similar neutral result held for patients with and without a history of hypertension. Furthermore, calcium channel blockers did not alter the benefit of the angiotensin converting enzyme inhibitor, captopril.

CONCLUSIONS

This analysis of the nonrandomized clinical use of calcium channel blockers in the postmyocardial infarction population with left ventricular dysfunction did not identify either a clinical deterioration or improvement with respect to subsequent cardiovascular events.

Clinical significance of mitral regurgitation after acute myocardial infarction. Survival and Ventricular Enlargement Investigators

BACKGROUND

Mitral regurgitation (MR) may complicate acute myocardial infarction (MI). However, it is not known whether mild MR is an independent predictor of post-MI outcome.

METHODS AND RESULTS

The study cohort consisted of 727 Survival and Ventricular Enlargement Study patients who underwent cardiac catheterization, including left ventriculography, up to 16 days after MI. Left ventriculograms were analyzed for diastolic and systolic volumes, global left ventricular sphericity, extent of wall motion abnormality, and endocardial curvature. The presence of MR was related to the risk of developing a cardiovascular event during 3.5 years of follow-up. MR was present in 141 patients (19.4%). Severe (3+) MR was present in only 2 patients. Patients with MR were more likely to have a persistently occluded infarct artery (MR versus no MR, 27.3% versus 15.2%; P=.001). Although the ejection fractions were similar, MR patients had larger end-systolic and end-diastolic volumes and more spherical ventricles than patients without MR. Sphericity change from diastole to systole was also significantly reduced in MR patients. Patients with MR were more likely to experience cardiovascular mortality (29% versus 12%; P<.001), severe heart failure (24% versus 16%; P=.0153), and the combined end point of cardiovascular mortality, severe heart failure, or recurrent myocardial infarction (47% versus 29%; P<.001). The presence of MR was an independent predictor of cardiovascular mortality (relative risk, 2.00; 95% CI, 1.28 to 3.04).

CONCLUSIONS

Mild MR is an independent predictor of post-MI mortality. As such, it adds important information for risk stratification of post-MI patients.

Ventricular dysfunction and the risk of stroke after myocardial infarction

BACKGROUND

In patients who have had a myocardial infarction, the long-term risk of stroke and its relation to the extent of left ventricular dysfunction have not been determined. We studied whether a reduced left ventricular ejection fraction is associated with an increased risk of stroke after myocardial infarction and whether other factors such as older age and therapy with anticoagulants, thrombolytic agents, or captopril affect long-term rates of stroke.

METHODS

We performed an observational analysis of prospectively collected data on 2231 patients who had left ventricular dysfunction after acute myocardial infarction who were enrolled in the Survival and Ventricular Enlargement trial. The mean follow-up was 42 months. Risk factors for stroke were assessed by both univariate and multivariate Cox proportional-hazards analysis.

RESULTS

Among these patients, 103 (4.6 percent) had fatal or nonfatal strokes during the study (rate of stroke per year of follow-up, 1.5 percent). The estimated five-year rate of stroke in all the patients was 8.1 percent. As compared with patients without stroke, patients with stroke were older (mean [+/-SD] age, 63+/-9 years vs. 59+/-11 years; P<0.001) and had lower ejection fractions (29+/-7 percent vs. 31+/-7 percent, P=0.01). Independent risk factors for stroke included a lower ejection fraction (for every decrease of 5 percentage points in the ejection fraction there was an 18 percent increase in the risk of stroke), older age, and the absence of aspirin or anticoagulant therapy. Patients with ejection fractions of < or = 28 percent after myocardial infarction had a relative risk of stroke of 1.86, as compared with patients with ejection fractions of more than 35 percent (P=0.01). The use of thrombolytic agents and captopril had no significant effect on the risk of stroke.

CONCLUSIONS

During the five years after myocardial infarction, patients have a substantial risk of stroke. A decreased ejection fraction and older age are both independent predictors of an increased risk of stroke. Anticoagulant therapy appears to have a protective effect against stroke after myocardial infarction.

Cost-effectiveness of captopril therapy after myocardial infarction

OBJECTIVES

This study sought to assess the cost-effectiveness of captopril therapy for survivors of myocardial infarction.

BACKGROUND

The recent randomized, controlled Survival and Ventricular Enlargement (SAVE) trial showed that captopril therapy improves survival in survivors of myocardial infarction with an ejection fraction < or = 40%. The present ancillary study was designed to determine how the costs required to achieve this increase in survival compared with those of other medical interventions.

METHODS

We developed a decision-analytic model to assess the cost-effectiveness of captopril therapy in 50- to 80-year old survivors of myocardial infarction with an ejection fraction < or = 40%. Data on costs, utilities (health-related quality of life weights) and 4-year survival were obtained directly from the SAVE trial, and long-term survival was estimated using a Markov model. In one set of analyses, we assumed that the survival benefit associated with captopril therapy would persist beyond 4 years (persistent-benefit analyses), whereas in another set we assumed that captopril therapy incurred costs but no survival benefit beyond 4 years (limited-benefit analyses).

RESULTS

In the limited-benefit analyses, the incremental cost-effectiveness of captopril therapy ranged from $3,600/quality-adjusted life-year for 80-year old patients to $60,800/quality-adjusted life-year for 50-year old patients. In the persistent-benefit analyses, incremental cost-effectiveness ratios ranged from $3,700 to $10,400/quality-adjusted life-year, depending on age. The outcome was generally not sensitive to changes in estimates of variables when they were varied individually over wide ranges. In a "worst-case" analysis, incremental cost-effectiveness ratios for captopril therapy remained favorable ($8,700 to $29,200/quality-adjusted life-year) for 60- to 80-year old patients but were higher ($217,600/quality-adjusted life-year) for 50-year old patients.

CONCLUSIONS

We conclude that the cost-effectiveness of captopril therapy for 50- to 80-year old survivors of myocardial infarction with a low ejection fraction compares favorably with other interventions for survivors of myocardial infarction.

Effect of infarct artery patency on prognosis after acute myocardial infarction. The Survival and Ventricular Enlargement Investigators

BACKGROUND

In patients with acute myocardial infarction (MI), early restoration of patency of the infarct-related artery (IRA) leads to preservation of left ventricular function and improved clinical outcome. However, there is evidence that the benefits associated with a patent IRA are out of proportion to the observed improvement in ventricular function and may result not only from salvage of ischemic myocardium but also from the opening of the IRA beyond a narrow postinfarct time window. The objectives of this study were (1) to assess the effect of IRA patency on outcome of patients after acute MI with left ventricular dysfunction while controlling for differences in left ventricular ejection fraction and the extent of coronary disease and (2) to determine the effect of angiotensin-converting enzyme (ACE) inhibitor therapy on patients with patent as well as occluded infarct arteries.

METHODS AND RESULTS

The Survival and Ventricular Enlargement (SAVE) study consisted of 2231 patients with a documented MI and a left ventricular ejection fraction < or = 40%. They were randomized to the ACE inhibitor captopril (50 mg TID) or placebo 3 to 16 days after MI and were followed for an average of 3.5 years. Left ventricular ejection fraction, measured with radionuclide left ventriculography, was repeated at the end of the follow-up period. The 946 patients in whom the patency of the IRA was established before randomization form the basis of this study. At cardiac catheterization averaging 4.2 days after infarction, 30.7% of patients had an initially occluded IRA. After revascularization, 162 of the 946 patients (17.1%) were left with an occluded IRA at the time of randomization. The 162 patients with persistently occluded IRAs and 784 with patent IRAs had similar clinical baseline characteristics, but those with occluded arteries had a slightly lower ejection fraction than the 784 patients with patent infarct arteries (30% versus 32%, P = .01). Cox proportional-hazards analyses showed that the independent predictors of all-cause mortality were hypertension (relative risk [RR] 1.94, P < .001), number of diseased coronary arteries (RR 1.68, P < .001), occluded IRA (RR 1.49, P = .039), ejection fraction (RR 1.36, P < .001), age (RR 1.10, P = .030), and use of beta-adrenergic receptor blocking agents (RR 0.60, P = .007). Independent predictors of a composite end point consisting of cardiovascular mortality, morbidity, or reduction of ejection fraction of > or = 9 units were occluded IRA (odds ratio [OR] 1.73, P = .002), hypertension (OR 1.71, P < .001), number of diseased vessels (OR 1.38, P < .001), ejection fraction (OR 1.18, P = .003), use of beta-adrenergic receptor blocking agents (OR 0.67, P = .007), and randomization to captopril (OR 0.70, P = .009).

CONCLUSIONS

IRA patency within 16 days after MI predicts a favorable clinical outcome, independent of the number of obstructed coronary arteries or of left ventricular function. The beneficial effect of ACE inhibition is independent of patency status of the IRA. These findings support the need for additional, prospective clinical trials of late reperfusion in MI patients.

Risk factors for the development of recurrent atrial fibrillation: role of pacing and clinical variables

Atrial fibrillation recurs in many patients treated with antiarrhythmic therapy to maintain sinus rhythm. From March 1985 to August 1991, 214 patients with recurrent symptomatic chronic or paroxysmal atrial fibrillation for which conventional antiarrhythmic agents had failed were treated with propafenone or sotalol. Baseline demographic data including the presence of pacing therapy were collected. Life-table estimates of the duration of freedom from atrial fibrillation were constructed on the basis of pacemaker status. Of 214 patients, 26 (12.1%) had pacing therapy. Patients with dual-chamber pacing were more likely to remain in sinus rhythm at 6 months (80%) than were patients with ventricular pacing (40%) or patients without pacing therapy (55%) (p = 0.002). A Cox univariate regression analysis demonstrated that dual-chamber pacing in contrast to ventricular pacing or no pacing was associated with a lower risk of recurrent atrial fibrillation. Clinical parameters such as age, gender, left atrial size, fibrillation pattern, drug assignment, ejection fraction, and underlying cardiac disease did not alter the risk of recurrent atrial fibrillation. Dual-chamber pacing was associated with a decreased likelihood of recurrent atrial fibrillation even after adjustment for other clinical covariates in a multivariate model (p = 0.04). In patients with recurrent atrial fibrillation treated with propafenone or sotalol, dual-chamber pacing improved maintenance of sinus rhythm.

Permanent pacemaker selection and subsequent survival in elderly Medicare pacemaker recipients

BACKGROUND

Dual-chamber pacemakers have been in use for more than 15 years. Although they may confer a physiological advantage over single-chamber ventricular pacemakers, they are more expensive and have a generally shorter service life than single-chamber devices. We carried out the present study to identify patient subgroups who were preferentially receiving greater or lesser proportions of dual-chamber devices and to determine whether the selection of different types of pacemakers was associated with differences in mortality.

METHODS AND RESULTS

We analyzed a 20% random national sample of all Medicare beneficiaries aged 65 years or older who underwent initial placement of a permanent pacemaker and were discharged in 1988, 1989, or 1990 (n = 36,312). The minimum follow-up for vital status was 1 year. The relation of pacemaker type to patient and provider characteristics was determined using logistic regression analysis. The relation between pacemaker type and mortality was determined using the Cox proportional hazards method. The proportion of dual-chamber systems that were received increased from 27.2% in 1988 to 37.0% in 1990 (P < .001). Dual-chamber pacemaker recipients were younger (P < .001) than ventricular pacemaker recipients. Other independent correlates of dual-chamber pacemaker selection included male sex (odds ratio and 95% confidence intervals, 1.18 and 1.12 to 1.24, respectively), atrioventricular block (1.59 and 1.51 to 1.67), congestive heart failure (1.14 and 1.08 to 1.20), atrial fibrillation (0.36 and 0.34 to 0.39), and the presence of a major noncardiac diagnosis (0.86 and 0.83 to 0.89). Nonmedical predictors of dual-chamber pacemaker selection included Medicaid eligibility (0.78 and 0.71 to 0.86), implantation in the western United States (1.19 and 1.10 to 1.29), implantation by a rural provider (0.70 and 0.65 to 0.76), hospitalization in a 500-bed-or-larger hospital (1.20 and 1.13 to 1.28), hospitalization in a private hospital (1.19 and 1.10 to 1.28), or hospitalization in a hospital with a catheterization laboratory (1.47 and 1.38 to 1.56). Dual-chamber pacemaker selection was an independent predictor of survival at 1 year (0.82 and 0.77 to 0.87) and at 2 years (0.82 and 0.77 to 0.87) after controlling for potentially confounding patient-level and hospital-level characteristics.

CONCLUSIONS

The present study describes important variations in the clinical practice of cardiac pacing, many of which are not based on clinical characteristics. Furthermore, the selection of a dual-chamber pacemaker is associated with increased survival. These results underscore the need for prospective, outcome-based clinical trials of pacemaker mode selection.

Postmyocardial infarction patients: experience from the SAVE trial

Improving patient survival is the ultimate goal after acute myocardial infarction. Although thrombolytics, aspirin, and beta-blockers have greatly decreased mortality, structural changes such as ventricular dilatation evolving within the myocardium during and after acute myocardial infarction indicate a poor prognosis. The Survival and Ventricular Enlargement trial demonstrated that when administered 3 to 16 days after acute myocardial infarction in selected patients, captopril, the angiotensin-converting enzyme inhibitor, reduces ventricular dilatation, prevents the development of congestive heart failure, and reduces morbidity and mortality. This paper reviews results of that trial and presents guidelines for effective captopril dosage after acute myocardial infarction.

Postmyocardial infarction patients: experience from the SAVE trial

Improving patient survival is the ultimate goal after acute myocardial infarction. Although thrombolytics, aspirin, and beta-blockers have greatly decreased mortality, structural changes such as ventricular dilatation evolving within the myocardium during and after acute myocardial infarction indicate a poor prognosis. The Survival and Ventricular Enlargement trial demonstrated that when administered 3 to 16 days after acute myocardial infarction in selected patients, captopril, the angiotensin-converting enzyme inhibitor, reduces ventricular dilatation, prevents the development of congestive heart failure, and reduces morbidity and mortality. This paper reviews results of that trial and presents guidelines for effective captopril dosage after acute myocardial infarction.

Effects of captopril on ischemic events after myocardial infarction. Results of the Survival and Ventricular Enlargement trial. SAVE Investigators

BACKGROUND

In the Survival and Ventricular Enlargement (SAVE) trial, recurrent myocardial infarction (MI) was the most important predictor of a poor outcome and conferred a sevenfold increase in risk of death. The purpose of this study was to determine the predictors of recurrent MI in study participants and to examine the influence of the angiotensin-converting enzyme inhibitor captopril on this and other myocardial ischemic events.

METHODS AND RESULTS

The 2231 patients had survived the acute phase of MI (3 to 16 days) and had a radionuclide ventricular ejection fraction < or = 40%. Patients were randomly assigned to receive double-blind treatment with either placebo or captopril and were followed for an average of 42 months. The influence of captopril on recurrent MI, cardiac revascularization procedures, and hospitalization with unstable angina was examined. The likelihood of recurrent MI was greater in patients with an MI or functional disability before the index infarction and higher systolic pressure (all P < .001) but was not influenced by baseline left ventricular ejection fraction. Therapy with captopril reduced the risk of development of recurrent MI by 25% (95% confidence intervals, 5% to 40%; P = .015) and the risk of death after recurrent MI by 32% (95% confidence intervals, 4% to 51%; P = .029). Captopril-assigned patients were also less likely to require cardiac revascularization procedures (P = .010), but hospitalization for unstable angina was unaltered. When all three of these major coronary ischemic events were considered together, captopril therapy reduced the risk (14% risk reduction; 95% confidence intervals, 0% to 26%; P = .047).

CONCLUSIONS

In post-MI patients with asymptomatic left ventricular dysfunction, long-term administration of captopril reduced recurrence of MI and the need for cardiac revascularization but had no influence on the rate of hospitalization with a discharge diagnosis of unstable angina. The finding that the recurrence of MI was independent of left ventricular ejection fraction suggests that captopril could be useful in preventing recurrent MI in patients with more preserved left ventricular function. The need for cardiac revascularization was reduced in patients receiving long-term captopril therapy, suggesting either an anti-ischemic effect or the ability of the angiotensin-converting enzyme inhibitor to modify the atherosclerotic process in survivors of MI.