Prospective economic evaluation alongside the non-invasive ventilation trial.

OBJECTIVE: To determine the cost-effectiveness of nasal continuous positive pressure (nCPAP) compared with nasal intermittent positive pressure ventilation (NIPPV) in the context of the reported randomized clinical trial. STUDY DESIGN: Using patient-level data from the clinical trial, we undertook a prospectively planned economic evaluation. We measured costs, from a third-party payer perspective in all patients, and from a societal perspective in a subgroup with a time horizon through the earlier of discharge, death or 44 weeks post-menstrual age. RESULTS: From the third-party payer perspective, the mean cost of hospitalization per infant was statistically similar, $143 745 in the NIPPV group compared to $140 403 in the nCPAP group. Cost-effectiveness evaluation revealed a 61% probability that NIPPV is more expensive and less effective than nCPAP. Similar results were found in subgroup analysis from a societal perspective. CONCLUSION: In addition to being clinically equivalent, economic evaluation confirms that NIPPV, as employed in this trial, is also not economically favorable.

Only high levels of dabigatran attenuate catheter thrombosis in vitro and in rabbits.

In patients with mechanical heart valves, thromboembolic events were more frequent with dabigatran, an oral thrombin inhibitor, than with warfarin. This observation raises the possibility that dabigatran may be less effective than conventional anticoagulants in patients with other blood-contacting devices, such as catheters. To address this, we compared the capacity of dabigatran and/or heparin to inhibit catheter-induced thrombin generation in vitro and to attenuate catheter occlusion in rabbits. Using a catheter-induced thrombin generation assay, concentrations of dabigatran over 100 ng/ml prolonged the lag time and time to peak thrombin, and reduced the peak thrombin concentration and endogenous thrombin potential in a concentration-dependent fashion. Compared with saline in a rabbit model of catheter thrombosis, dabigatran prolonged the mean time to catheter occlusion by 2.9- and 1.9-fold when plasma levels were 173 and 140 ng/ml, respectively; values comparable to median peak levels in humans given dabigatran 150 mg twice daily. In contrast, low-dose dabigatran, which produced a level of 60 ng/ml; a value comparable to the trough level of dabigatran in humans, did not prolong the time to occlusion. Whereas a 70 U/kg bolus of heparin prolonged the mean time to occlusion by 3.4-fold, a 15 U/kg bolus had no effect. When low-dose dabigatran was given in combination with 15 U/kg heparin, the mean time to occlusion was prolonged by 2.7-fold. These findings suggest that only peak levels of dabigatran are sufficient to prevent catheter-induced clotting unless supplemented heparin is given.

Cerebral hemorrhage after intra-arterial thrombolysis for ischemic stroke: the PROACT II trial.

OBJECTIVE: To analyze the frequency, clinical characteristics, and predictors of symptomatic intracerebral hemorrhage (ICH) after intraarterial (IA) thrombolysis with recombinant pro-urokinase (r-proUK) in acute ischemic stroke. METHOD: The authors conducted an exploratory analysis of symptomatic ICH from a randomized, controlled clinical trial of IA thrombolysis with r-proUK for patients with angiographically documented occlusion of the middle cerebral artery within 6 hours from stroke onset. Patients (n = 180) were randomized in a ratio of 2:1 to either 9 mg IA r-proUK over 120 minutes plus IV fixed-dose heparin or IV fixed-dose heparin alone. As opposed to intention to treat, this analysis was based on "treatment received" and includes 110 patients given r-proUK and 64 who did not receive any thrombolytic agent. The remaining six patients received out-of-protocol urokinase and were excluded from analysis. The authors analyzed centrally adjudicated ICH with associated neurologic deterioration (increase in NIH Stroke Scale [NIHSS] score of > or =4 points) within 36 hours of treatment initiation. RESULTS: Symptomatic ICH occurred in 12 of 110 patients (10.9%) treated with r-proUK and in two of 64 (3.1%) receiving heparin alone. ICH symptoms in r-proUK-treated patients occurred at a mean of 10.2 +/- 7.4 hours after the start of treatment. Mortality after symptomatic ICH was 83% (10/12 patients). Only blood glucose was significantly associated with symptomatic ICH in r-proUK-treated patients based on univariate analyses of 24 variables: patients with baseline glucose >200 mg/dL experienced a 36% risk of symptomatic ICH compared with 9% for those with < or =200 mg/dL (p = 0.022; relative risk, 4.2; 95% CI, 1.04 to 11.7). CONCLUSIONS: Symptomatic ICH after IA thrombolysis with r-proUK for acute ischemic stroke occurs early after treatment and has high mortality. The risk of symptomatic ICH may be increased in patients with a blood glucose >200 mg/dL at stroke onset.

Effect of clinical risk stratification on cost-effectiveness of the implantable cardioverter-defibrillator: the Canadian implantable defibrillator study.

BACKGROUND: Three randomized clinical trials showed that implantable cardioverter-defibrillators (ICDs) reduce the risk of death in survivors of ventricular tachyarrhythmias, but the cost per year of life gained is high. A substudy of the Canadian Implantable Defibrillator Study (CIDS) showed that 3 clinical factors, age >/=70 years, left ventricular ejection fraction /=2 of 3 risk factors. Incremental cost-effectiveness of ICD therapy was computed as the ratio of the difference in mean cost to the difference in life expectancy between the 2 groups. Over 6.3 years, the mean cost per patient in the ICD group was Canadian (C) $87 715 versus $38 600 in the amiodarone group (C$1 approximately US$0.67). Life expectancy for the ICD group was 4.58 years versus 4.35 years for amiodarone, for an incremental cost-effectiveness of ICD therapy of C$213 543 per life-year gained. The cost per life-year gained in patients with >/=2 factors was C$65 195, compared with C$916 659 with <2 risk factors. CONCLUSIONS: The cost-effectiveness of ICD therapy varies by patient risk factor status. The use of ICD therapy in patients who have >/=2 risk factors of age >/=70 years, left ventricular ejection fraction

Progression to chronic atrial fibrillation after pacing: the Canadian Trial of Physiologic Pacing. CTOPP Investigators.

OBJECTIVES: This study examined the effect of physiologic pacing on the development of chronic atrial fibrillation (CAF) in the Canadian Trial Of Physiologic Pacing (CTOPP). BACKGROUND: The role of physiologic pacing to prevent CAF remains unclear. Small randomized studies have suggested a benefit for patients with sick sinus syndrome. No data from a large randomized trial are available. METHODS: The CTOPP randomized patients undergoing first pacemaker implant to ventricular-based or physiologic pacing (AAI or DDD). Patients who were prospectively found to have persistent atrial fibrillation (AF) lasting greater than or equal to one week were defined as having CAF. Kaplan-Meier plots for the development of CAF were compared by log-rank test. The effect of baseline variables on the benefit of physiologic pacing was evaluated by Cox proportional hazards modeling. RESULTS: Physiologic pacing reduced the development of CAF by 27.1%, from 3.84% per year to 2.8% per year (p = 0.016). Three clinical factors predicted the development of CAF: age > or =74 years (p = 0.057), sinoatrial (SA) node disease (p < 0.001) and prior AF (p < 0.001). Subgroup analysis demonstrated a trend for patients with no history of myocardial infarction or coronary disease (p = 0.09) as well as apparently normal left ventricular function (p = 0.11) to derive greatest benefit. CONCLUSIONS: Physiologic pacing reduces the annual rate of development of chronic AF in patients undergoing first pacemaker implant. Age > or =74 years, SA node disease and prior AF predicted the development of CAF. Patients with structurally normal hearts appear to derive greatest benefits.

Long-term effects of indomethacin prophylaxis in extremely-low-birth-weight infants.

BACKGROUND: The prophylactic administration of indomethacin reduces the frequency of patent ductus arteriosus and severe intraventricular hemorrhage in very-low-birth-weight infants (those with birth weights below 1500 g). Whether prophylaxis with indomethacin confers any long-term benefits that outweigh the risks of drug-induced reductions in renal, intestinal, and cerebral blood flow is not known. METHODS: Soon after they were born, we randomly assigned 1202 infants with birth weights of 500 to 999 g (extremely low birth weight) to receive either indomethacin (0.1 mg per kilogram of body weight) or placebo intravenously once daily for three days. The primary outcome was a composite of death, cerebral palsy, cognitive delay, deafness, and blindness at a corrected age of 18 months. Secondary long-term outcomes were hydrocephalus necessitating the placement of a shunt, seizure disorder, and microcephaly within the same time frame. Secondary short-term outcomes were patent ductus arteriosus, pulmonary hemorrhage, chronic lung disease, ultrasonographic evidence of intracranial abnormalities, necrotizing enterocolitis, and retinopathy. RESULTS: Of the 574 infants with data on the primary outcome who were assigned to prophylaxis with indomethacin, 271 (47 percent) died or survived with impairments, as compared with 261 of the 569 infants (46 percent) assigned to placebo (odds ratio, 1.1; 95 percent confidence interval, 0.8 to 1.4; P=0.61). Indomethacin reduced the incidence of patent ductus arteriosus (24 percent vs. 50 percent in the placebo group; odds ratio, 0.3; P<0.001) and of severe periventricular and intraventricular hemorrhage (9 percent vs. 13 percent in the placebo group; odds ratio, 0.6; P=0.02). No other outcomes were altered by the prophylactic administration of indomethacin. CONCLUSIONS: In extremely-low-birth-weight infants, prophylaxis with indomethacin does not improve the rate of survival without neurosensory impairment at 18 months, despite the fact that it reduces the frequency of patent ductus arteriosus and severe periventricular and intraventricular hemorrhage.

Oxazole synthesis with minimal purification: synthesis and application of a ROMPgel Tosmic reagent.

[figure: see text] The synthesis of ring opening metathesis, polymer-supported Tosmic reagent 1 is described. This reagent was utilized in the conversion of aldehydes to oxazoles in good yields and purities.

Relationship between pacemaker dependency and the effect of pacing mode on cardiovascular outcomes.

BACKGROUND: A recently completed trial, the Canadian Trial of Physiological Pacing (CTOPP), showed that physiological pacing did not significantly reduce mortality, stroke, or heart failure hospitalization, but it did show that atrial fibrillation occurred less frequently in patients with physiological pacing. Many pacemaker patients experience only transient bradyarrhythmias with an adequate unpaced heart rate (UHR) and are not pacemaker-dependent. The purpose of the present analysis was to determine if pacemaker-dependent patients have an increased benefit from physiological pacing compared with non-pacemaker-dependent patients. METHODS AND RESULTS: Of 2568 patients included in the CTOPP trial, 2244 patients had a pacemaker dependency test performed at the first follow-up visit. The yearly event rate of cardiovascular death or stroke steadily increased with decreasing UHR in the ventricular pacing group, but it remained constant in the physiological pacing group. When the patients were subdivided to UHR 60 bpm, there was an interaction between pacing mode treatment and UHR subgroup. The Kaplan-Meier plot confirmed a physiological pacing advantage only in the UHR

Cost-effectiveness of the implantable cardioverter-defibrillator: results from the Canadian Implantable Defibrillator Study (CIDS).

BACKGROUND: In the Canadian Implantable Defibrillator Study (CIDS), we assessed the cost-effectiveness of the implantable cardioverter-defibrillator (ICD) in reducing the risk of death in survivors of previous ventricular tachycardia (VT) or fibrillation (VF). METHODS AND RESULTS: Healthcare resource use was collected prospectively on the first 430 patients enrolled in CIDS (n=212 ICD, n=218 amiodarone). Mean cost per patient, adjusted for censoring, was computed for each group based on initial therapy assignment. Incremental cost-effectiveness of ICD therapy was computed as the ratio of the difference in cost (ICD minus amiodarone) to the difference in life expectancy (both discounted at 3% per year). All costs are in 1999 Canadian dollars (C$1 approximately US$0.65). Over 6.3 years, mean cost per patient in the ICD group was C$87 715 versus C$38 600 in the amiodarone group (difference C$49 115; 95% CI C$25 502 to C$69 508). Life expectancy for the ICD group was 4.58 years versus 4.35 years for amiodarone (difference 0.23, 95% CI -0.09 to 0.55), for incremental cost-effectiveness of ICD therapy of C$213 543 per life-year gained. ICD benefit was greater in patients with low left ventricular ejection fraction (<35%), and cost-effectiveness in this group was more attractive (C$108 484). Alternative extrapolations of survival benefit and costs to 12 years indicated cost-effectiveness in the range of C$100 000 to C$150 000 per life-year gained. CONCLUSIONS: At C$213 543, the value for the money offered by ICD therapy is not attractive by currently accepted standards. Further research is warranted to identify the indications and patient subgroups for whom ICDs are a cost-effective use of resources.

Meta-analysis of the implantable cardioverter defibrillator secondary prevention trials. AVID, CASH and CIDS studies. Antiarrhythmics vs Implantable Defibrillator study. Cardiac Arrest Study Hamburg . Canadian Implantable Defibrillator Study.

AIMS: Three randomized trials of implantable cardioverter defibrillator (ICD) therapy vs medical treatment for the prevention of death in survivors of ventricular fibrillation or sustained ventricular tachycardia have been reported with what might appear to be different results. The present analysis was performed to obtain the most precise estimate of the efficacy of the ICD, compared to amiodarone, for prolonging survival in patients with malignant ventricular arrhythmia. METHODS AND RESULTS: Individual patient data from the Antiarrhythmics vs Implantable Defibrillator (AVID) study, the Cardiac Arrest Study Hamburg (CASH) and the Canadian Implantable Defibrillator Study (CIDS) were merged into a master database according to a pre-specified protocol. Proportional hazard modelling of individual patient data was used to estimate hazard ratios and to investigate subgroup interactions. Fixed effect meta-analysis techniques were also used to evaluate treatment effects and to assess heterogeneity across studies. The classic fixed effects meta-analysis showed that the estimates of ICD benefit from the three studies were consistent with each other (P heterogeneity=0.306). It also showed a significant reduction in death from any cause with the ICD; with a summary hazard ratio (ICD:amiodarone) of 0.72 (95% confidence interval 0.60, 0.87;P=0.0006). For the outcome of arrhythmic death, the hazard ratio was 0.50 (95% confidence interval 0.37, 0.67;P<0.0001). Survival was extended by a mean of 4.4 months by the ICD over a follow-up period of 6 years. Patients with left ventricular ejection fraction < or = 35% derived significantly more benefit from ICD therapy than those with better preserved left ventricular function. Patients treated before the availability of non-thoracotomy ICD implants derived significantly less benefit from ICD therapy than those treated in the non-thoracotomy era. CONCLUSION: Results from the three trials of the ICD vs amiodarone are consistent with each other. There is a 28% reduction in the relative risk of death with the ICD that is due almost entirely to a 50% reduction in arrhythmic death.

Impact of fluconazole prophylaxis on fungal colonization and infection rates in neutropenic patients. The Canadian Fluconazole Study.

Fungal colonization profiles from four different anatomical sites were evaluated in 266 neutropenic cancer patients receiving intensive cytotoxic therapy for acute leukaemia or for autologous marrow transplantation. At the beginning of chemotherapy patients were allocated randomly to receive oral fluconazole 400 mg daily or an identical placebo until prophylaxis failure or marrow recovery. Candida albicans colonization was reduced from 30 to 10% in the fluconazole recipients while it increased from 32 to 57% in the placebo patients (P<0.001). By the end of prophylaxis, colonization with non-albicans Candida species increased from 7 to 21% and 8 to 18% in the fluconazole and placebo patients, respectively (P = 0.396). Although Candida glabrata was isolated more frequently at the end of the prophylactic period in the fluconazole patients than in the placebo patients (16 versus 7%), only one definite invasive C. glabrata infection was noted. Overall, definite invasive fungal infections were documented in 26 patients [four fluconazole versus 22 placebo patients (P< or =0.001)]. In 23 (92%) patients the infections were caused by persistently colonizing or newly acquired organisms. While probable invasive fungal infections were noted in five fluconazole patients, 10 placebo patients were also affected (P = 0.19). An end-of-prophylaxis colonization index >0.25 was 76% sensitive but only 69% specific for invasive fungal infection. However, a colonization index < or =0.25 at baseline had a negative predictive value of 88% for development of invasive fungal infection. Fluconazole prophylaxis decreased colonization by fungi and subsequent invasive fungal infections in neutropenic cancer patients.

The defibrillator in acute myocardial infarction trial (DINAMIT): study protocol.

BACKGROUND: The implantable cardioverter/defibrillator (ICD) has been shown to be superior to antiarrhythmic drug therapy for the secondary prevention of sudden cardiac death. Its role in the primary prevention of sudden death after myocardial infarction is unknown. Methods and Results The Defibrillator in Acute Myocardial Infarction Trial (DINAMIT) is a randomized, open-label, parallel-group comparison of ICD therapy versus no ICD therapy in selected survivors of acute myocardial infarction. It will test the hypothesis that reduction of sudden arrhythmogenic death by means of the ICD will result in reduction of overall mortality rates in patients at high risk after acute myocardial infarction. Accordingly, this international multicenter study aims to enroll patients shortly after their infarction (day 6 to day 40) who have reduced left ventricular function (left ventricular ejection fraction

Impurity annihilation: chromatography-free parallel Mitsunobu reactions.

Mitsunobu reaction of an alcohol ROH with a carboxylic acid, phthalimide, or N-hydroxyphthalimide (NuH) using DNAD (4) and (diphenylphosphino)polystyrene (11) gave the products RNu. Ring-opening metathetic polymerization of the side product DNADH(2) (3) using Cl(2)(Cy(3)P)(2)Ru=CHPh (13) and filtration, to remove poly(DNADH(2)), (diphenylphosphino)polystyrene 11, its oxide, and its adduct with excess DNAD, gave RNu (43-100%, 86-96% purity) without recourse to chromatography.

The impact of time to thrombolytic treatment on outcome in patients with acute myocardial infarction. For the CORE investigators (Collaborative Organisation for RheothRx Evaluation).

OBJECTIVES: To examine the impact of time to thrombolytic treatment on multiple acute outcome variables in a single trial of thrombolysis in acute myocardial infarction. DESIGN AND PATIENTS: Mortality and reinfarction rate were measured in 2770 patients with acute myocardial infarction who received thrombolysis within 12 hours in CORE, an international, dose ranging trial of poloxamer 188. Tc-99m sestamibi infarct size and radionuclide angiographic ejection fraction substudies included 1099 and 1074 patients, respectively. RESULTS: Time to thrombolysis, subgrouped by intervals (< 2, 2-4, > or = 4-6, and > or = 6 hours), was significantly associated with infarct size (median 15.0%, 18.5%, 22.0%, 18.5% of left ventricle; p = 0.033), mean (SD) ejection fraction (51.5 (12.0)%, 48. 3 (13.9)%, 48.2 (13.3)%, 48.2 (15.0)%; p = 0.006), 35 day mortality (5.7%, 7.1%, 7.9%, 12.5%; p = 0.0004), six month mortality (7.3%, 8. 6%, 10.4%, 15.5%; p < 0.0001), and 35 day reinfarction rate (6.1%, 3. 2%, 4.0%, 0.9%; p = 0.0001). CONCLUSIONS: In this single large trial, the beneficial effect of time to thrombolysis on infarct size and ejection fraction was restricted to treatment given within two hours of symptom onset, while the effect on mortality was evident over all time intervals. Reinfarction rate was higher in patients treated with earlier thrombolysis.

Chromatography-free synthesis of 1,2,4-oxadiazoles using ROMPGEL-supported acylating reagents.

1,2,4-Oxadiazoles were synthesized in solution from aromatic amidoximes and acylating agents supported on a ring opening metathesis polymer (ROMPGEL) backbone. High yields and purities of the 1,2,4-oxadiazoles were obtained with minimal purification.

Canadian implantable defibrillator study (CIDS) : a randomized trial of the implantable cardioverter defibrillator against amiodarone.

BACKGROUND: Patients surviving ventricular fibrillation (VF) or sustained ventricular tachycardia (VT) are at a high risk of death due to a recurrence of arrhythmia. The implantable cardioverter defibrillator (ICD) terminates VT or VF, but it is not known whether this device prolongs life in these patients compared with medical therapy with amiodarone. METHODS AND RESULTS: A total of 659 patients with resuscitated VF or VT or with unmonitored syncope were randomly assigned to treatment with the ICD or with amiodarone. The primary outcome measure was all-cause mortality, and the secondary outcome was arrhythmic death. A total of 328 patients were randomized to receive an ICD. A thoracotomy was done in 33, no ICD was implanted in 18, and the rest had a nonthoracotomy ICD. All 331 patients randomized to amiodarone received it initially. At 5 years, 85.4% of patients assigned to amiodarone were still receiving it at a mean dose of 255 mg/day, 28.1% of ICD patients were also receiving amiodarone, and 21.4% of amiodarone patients had received an ICD. A nonsignificant reduction in the risk of death was observed with the ICD, from 10.2% per year to 8.3% per year (19.7% relative risk reduction; 95% confidence interval, -7.7% to 40%; P=0.142). A nonsignificant reduction in the risk of arrhythmic death was observed, from 4.5% per year to 3.0% per year (32.8% relative risk reduction; 95% confidence interval, -7.2% to 57.8%; P=0.094). CONCLUSIONS: A 20% relative risk reduction occurred in all-cause mortality and a 33% reduction occurred in arrhythmic mortality with ICD therapy compared with amiodarone; this reduction did not reach statistical significance.

The stroke prognosis instrument II (SPI-II) : A clinical prediction instrument for patients with transient ischemia and nondisabling ischemic stroke.

BACKGROUND AND PURPOSE: In 1991 we developed the Stroke Prognosis Instrument (SPI-I) to stratify patients with transient ischemic attack or ischemic stroke by prognosis for stroke or death in 2 years. In this article we validate and improve SPI-I (creating SPI-II). METHODS: To validate SPI-I, we applied it to 4 test cohorts and calculated pooled outcome rates. To create SPI-II, we incorporated new predictive variables identified in 1 of the test cohorts and validated it in the other 3 cohorts. RESULTS: For SPI-I, pooled rates (all 4 test cohorts) of stroke or death within 2 years in risk groups I, II, and III were 9%, 17%, and 24%, respectively (P<0.01, log-rank test). SPI-II was created by adding congestive heart failure and prior stroke to SPI-I. Each patient's risk group was determined by the total score for 7 factors: congestive heart failure (3 points); diabetes (3 points); prior stroke (3 points); age >70 years (2 points); stroke for the index event (not transient ischemic attack) (2 points); hypertension (1 point); and coronary artery disease (1 point). Risk groups I, II, and III comprised patients with 0 to 3, 4 to 7, and 8 to 15 points, respectively. For SPI-I, pooled rates (3 cohorts excluding the SPI-II development cohort) of stroke or death within 2 years in risk groups I, II, and III were 9%, 17%, and 23%, respectively. For SPI-II, pooled rates were 10%, 19%, and 31%, respectively. In receiver operator characteristic analysis, the area under the curve was 0.59 (95% CI, 0.57 to 0.60) for SPI-I and 0.63 (95% CI, 0.62 to 0.65) for SPI-II, confirming the better performance of the latter. CONCLUSIONS: Compared with SPI-I, SPI-II achieves greater discrimination in outcome rates among risk groups. SPI-II is ready for use in research design and may have a role in patient counseling.

Effects of physiologic pacing versus ventricular pacing on the risk of stroke and death due to cardiovascular causes. Canadian Trial of Physiologic Pacing Investigators.

BACKGROUND: Evidence suggests that physiologic pacing (dual-chamber or atrial) may be superior to single-chamber (ventricular) pacing because it is associated with lower risks of atrial fibrillation, stroke, and death. These benefits have not been evaluated in a large, randomized, controlled trial. METHODS: At 32 Canadian centers, patients without chronic atrial fibrillation who were scheduled for a first implantation of a pacemaker to treat symptomatic bradycardia were eligible for enrollment. We randomly assigned patients to receive either a ventricular pacemaker or a physiologic pacemaker and followed them for an average of three years. The primary outcome was stroke or death due to cardiovascular causes. Secondary outcomes were death from any cause, atrial fibrillation, and hospitalization for heart failure. RESULTS: A total of 1474 patients were randomly assigned to receive a ventricular pacemaker and 1094 to receive a physiologic pacemaker. The annual rate of stroke or death due to cardiovascular causes was 5.5 percent with ventricular pacing, as compared with 4.9 percent with physiologic pacing (reduction in relative risk, 9.4 percent; 95 percent confidence interval, -10.5 to 25.7 percent [the negative value indicates an increase in risk]; P=0.33). The annual rate of atrial fibrillation was significantly lower among the patients in the physiologic-pacing group (5.3 percent) than among those in the ventricular-pacing group (6.6 percent), for a reduction in relative risk of 18.0 percent (95 percent confidence interval, 0.3 to 32.6 percent; P=0.05). The effect on the rate of atrial fibrillation was not apparent until two years after implantation. The observed annual rates of death from all causes and of hospitalization for heart failure were lower among the patients with a physiologic pacemaker than among those with a ventricular pacemaker, but not significantly so (annual rates of death, 6.6 percent with ventricular pacing and 6.3 percent with physiologic pacing; annual rates of hospitalization for heart failure, 3.5 percent and 3.1 percent, respectively). There were significantly more perioperative complications with physiologic pacing than with ventricular pacing (9.0 percent vs. 3.8 percent, P<0.001). CONCLUSIONS: Physiologic pacing provides little benefit over ventricular pacing for the prevention of stroke or death due to cardiovascular causes.

Monthly intra-individual variation in lipids over a 1-year period in 22 normal subjects.

OBJECTIVES: Previous reports on biological variation in lipids differ widely in the time interval between sampling, the number of samples analyzed per patient and the total study period. The present investigation was carried out to determine monthly intra-individual variation in lipids over 1 year and to establish whether there was a consistent change in lipid values over the summer months. The importance of taking this variation into consideration during the assessment of risk of coronary heart disease (CHD) was also examined. DESIGN AND METHODS: Cholesterol, triglycerides, HDL, apo A1, and apo B were measured at monthly intervals for 12 months in 22 healthy, free-living volunteers (11 females, 11 males) by standardized methods. RESULTS: When compared to analytical variation, biological variation was the dominant component of the intra-individual changes observed during the 1-year study period. As expected, triglycerides showed the greatest biological variation; the ratio of biological/analytical variation was 33.1. Much smaller ratios were observed for the other lipids measured in this study with values ranging from 4.2 to 6.8. Different subjects attained their maximum and minimum values in virtually every month of the year. There were significant reductions in cholesterol, HDL, LDL, and apo A1 in the summer months while triglycerides showed a non-significant increase and apo B a non-significant decrease during this period. CONCLUSIONS: All the analytes showed considerable intra-individual variation. It is, therefore, important to measure lipids sequentially over several weeks to arrive at an average value for risk stratification for CHD.