Search PubMed⌕ Search

Biomedical subjects

G C Flaker

Publications and source records attributed to G C Flaker.

At least 19 recordsLinked to original sources
PubMed2002

Atrial fibrillation after coronary bypass: etiology and pharmacologic prevention.

Coronary bypass surgery is performed on over 400,000 patients each year in the United States. Atrial Fibrillation (AF) is the most common complication after bypass surgery. The significance of its occurrence lies not only in the potentially dangerous and physiologic derangement to patients, but also in the impact it has on the utilization of health care resources. Several clinical observations suggest that the occurrence of atrial fibrillation after bypass surgery has some unique features related to the perioperative circumstances. Numerous therapies, both pharmacologic and non-pharmacologic have been tested to prevent this tenacious problem. Its persistence continues to intrigue cardio-thoracic surgeons, cardiologists, anesthesiologists and the insurers alike. In this review we discuss the published literature on postbypass AF, with a special emphasis on pharmacologic prevention.

Adrenergic beta-Antagonists↗
PubMed2001

Minute ventilation-sensor driven pacemaker related difficulty in weaning from mechanical ventilation: a case report.

BACKGROUND: Minute ventilation responsive rate adaptive pacemaker improves exercise performance in the patients with chronotropic insufficiency. The usual complications of these pacemakers are related to pacemaker implantation, rather than to the rate adaptive function. CASE REPORT: We report a patient with mitral stenosis and atrial fibrillation with a VVIR pacemaker, who was mechanically ventilated for respiratory failure. The patient could not be weaned because of the minute ventilation driven increased heart rates. Subsequently the rate adaptive function was switched off and the patient was successfully weaned from ventilator. CONCLUSIONS: Difficulty in weaning from mechanical ventilation can be a serious complication in patients with organic heart disease, who depend on diastolic filling time for adequate cardiac output.

Aged↗
PubMed2000

Early percutaneous coronary intervention, platelet inhibition with eptifibatide, and clinical outcomes in patients with acute coronary syndromes. PURSUIT Investigators.

BACKGROUND: Platelet glycoprotein (GP) IIb/IIIa antagonists prevent the composite end point of death or myocardial infarction (MI) in patients with acute coronary syndromes. There is uncertainty about whether this effect is confined to patients who have percutaneous coronary interventions (PCIs) and whether PCIs further prevent death or MI in patients already treated with GP IIb/IIIa antagonists. METHODS AND RESULTS: PURSUIT patients were treated with the GP IIb/IIIa antagonist eptifibatide or placebo; PCIs were performed according to physician practices. In 2253 of 9641 patients (23.4%), PCI was performed by 30 days. Early (<72 hours) PCI was performed in 1228 (12.7%). In 34 placebo patients (5.5%) and 10 treated with eptifibatide (1.7%) (P=0.001), MI preceded early PCI. In patients censored for PCI across the 30-day period, there was a significant reduction in the primary composite end point in eptifibatide patients (P=0.035). Eptifibatide reduced 30-day events in patients who had early PCI (11.6% versus 16.7%, P=0.01) and in patients who did not (14.6% versus 15.6%, P=0.23). After adjustment for PCI propensity, there was no evidence that eptifibatide treatment effect differed between patients with or without early PCI (P for interaction=0.634). PCI was not associated with a reduction of the primary composite end point but was associated with a reduced (nonspecified) composite of death or Q-wave MI. This association disappeared after adjustment for propensity for early PCI. CONCLUSIONS: Eptifibatide reduced the composite rates of death or MI in PCI patients and those managed conservatively.

Acute Disease↗
PubMed2000

Should interventional cardiac catheterization procedures take place at the time of diagnostic procedures?

BACKGROUND: In many cardiac catheterization laboratories interventional procedures are performed at a date later than the diagnostic study, causing increased hospital days and costs. Few data exist which compare procedural success, complications, and costs between procedures performed at the time of diagnostic study and those performed later. HYPOTHESIS: The purpose of this study was to evaluate the safety and success of same-day interventional procedures and to quantitate hospital cost savings with this strategy. METHOD: In all, 357 consecutive patients who underwent an elective interventional procedure of a native coronary artery either at the time of diagnostic study (same day, n = 244) or later (delayed, n = 113) were reviewed. Procedural success [< 30% residual lesion post-percutaneous transluminal coronary angioplasty (PTCA) or 0% residual lesion post-stent], major complications [death, emergent coronary artery bypass grafting (CABG), myocardial infarction, and ventricular fibrillation], hospital days, and costs were analyzed. Procedural expense, including the diagnostic and interventional procedure in the cardiac catheterization laboratory, and hospital expense were analyzed. RESULTS: Both groups were similar in terms of age, gender, coronary risk factors, indications (myocardial infarction, unstable angina, abnormal stress test), the culprit coronary artery, type of intervention (PTCA, stent), and lesion complexity (type A, B, C). The average hospital stay for the two groups was 4.37 +/- 2 and 6.55 +/- 2.4 days, respectively (p < 0.0001). The procedural charges were $8,207.99 and 10,581.87, respectively (p < 0.0001). CONCLUSION: Catheter intervention performed at the same time as the diagnostic cardiac catheterization procedure is as successful and as safe as that performed at a later date. Hospital stay and costs, as well as procedural expenses are significantly reduced by this practice.

Adult↗
PubMed2000

Adverse outcomes and predictors of underuse of antithrombotic therapy in medicare beneficiaries with chronic atrial fibrillation.

BACKGROUND AND PURPOSE: Antithrombotic therapy can prevent strokes and transient ischemic attacks (TIAs) in carefully selected patients who have chronic nonvalvular atrial fibrillation (NVAF). Our objectives were 3-fold: to document the use of warfarin and aspirin therapy in Missouri Medicare beneficiaries with chronic NVAF; to identify factors associated with warfarin and aspirin underuse; and to determine the association between prescription of warfarin and aspirin at hospital discharge and adverse outcomes in this elderly, frail population. METHODS: We linked chart reviews from all Missouri hospitals to Medicare claims data from 1993 to 1996. From chart reviews, we documented Medicare beneficiaries' demographic factors, comorbid conditions, and antithrombotic therapy prescribed at the time of hospital discharge. From Medicare claims, we determined the date of outcomes-death from any cause or hospitalization for an ischemic event (a stroke, a TIA, or a myocardial infarction). RESULTS: Only 328 (55%) of the 597 Medicare beneficiaries were prescribed antithrombotic therapy at hospital discharge: 34% received warfarin and 21% received aspirin. Advanced age, female gender, and rural residency predicted underuse of antithrombotic therapy. After controlling for these factors, as well as stroke risk factors and contraindications to anticoagulation, the prescription of warfarin was associated with a 24% relative risk reduction (RRR) in adverse outcomes (P=0.003). Prescription of aspirin was associated with a nonsignificant 5% RRR in these events (P=0.56). CONCLUSIONS: The underuse of antithrombotic therapy in Medicare beneficiaries who have NVAF is associated with measurable adverse outcomes. The benefit of warfarin therapy may extend to frail, elderly patients, a group that was excluded from randomized controlled trials. The role of antiplatelet therapy in this population deserves further study because many of these patients have relative contraindications to warfarin.

Aged↗
PubMed1999

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.

Adult↗
PubMed1999

Pravastatin prevents clinical events in revascularized patients with average cholesterol concentrations. Cholesterol and Recurrent Events CARE Investigators.

OBJECTIVES: This analysis was carried out to determine if revascularized patients derive benefit from the 3-hydroxy-3 methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor pravastatin. BACKGROUND: The HMG-CoA reductase inhibitors result in substantial reductions in serum cholesterol and stabilization of atherosclerotic plaques in patients with coronary artery disease. METHODS: Pravastatin was found to reduce clinical cardiovascular events in the Cholesterol and Recurrent Events (CARE) trial consisting of 4,159 patients with a documented myocardial infarction and an average cholesterol level (mean 209 mg/dl and all <240 mg/dl). A total of 2,245 patients underwent coronary revascularization before randomization including 1,154 patients with percutaneous transluminal coronary angioplasty (PTCA) alone, 876 patients with coronary artery bypass graft (CABG) alone, and 215 patients with both procedures. Clinical events in revascularized patients were compared between patients on placebo and on pravastatin. RESULTS: In the 2,245 patients who had undergone revascularization, the primary endpoint of coronary heart disease death or nonfatal myocardial infarction (MI) was reduced by 4.1% with pravastatin (relative risk [RR] reduction 36%, 95% confidence interval [CI] 17 to 51, p = 0.001). Fatal or nonfatal MI was reduced by 3.3% (RR reduction 39%, 95% CI 16 to 55, p = 0.002), postrandomization repeat revascularization was reduced by 2.6% (RR reduction 18%, 95% CI 1 to 33, p = 0.068) and stroke was reduced by 1.5% (RR reduction 39%, 95% CI 3 to 62, p = 0.037) with pravastatin. Pravastatin was beneficial in both the 1,154 PTCA patients and in the 1,091 CABG patients who had undergone revascularization before randomization. CONCLUSIONS: Pravastatin reduced clinical events in revascularized postinfarction patients with average cholesterol levels. This therapy was well tolerated and its use should be considered in most patients following coronary revascularization.

Angioplasty, Balloon, Coronary↗
PubMed1999

Underutilization of antithrombotic therapy in elderly rural patients with atrial fibrillation.

BACKGROUND: Antithrombotic agents are underutilized in elderly patients with atrial fibrillation. In a peer-review audit of antithrombotic use in Missouri, rural patients were given antithrombotic therapy less often than rural patients for unclear reasons. METHODS AND RESULTS: The charts of 597 hospitalized Medicare patients discharged between October 1, 1993, and December 31, 1994, from urban and rural hospitals in Missouri were reviewed. In addition to antithrombotic therapy prescribed at the time of discharge, patient and physician information, relative contraindications to antithrombotic therapy, and risk factors for stroke were identified. Rural and urban patients were similar in terms of age, sex, and risk factors for stroke. At least one stroke risk factor was noted in 87% of rural patients and in 84% of urban patients. Urban patients were more likely to have a relative contraindication to antithrombotic therapy compared with rural patients (66% vs 54%, P =.04) but received antithrombotic therapy more often (58% vs 47%, P =.02). Cardiologists prescribed antithrombotic therapy significantly more often than noncardiologists (69% vs 52%, P =.003). CONCLUSIONS: Elderly rural patients with atrial fibrillation receive antithrombotic therapy less frequently than urban patients despite having a similar high-risk profile and fewer relative contraindications. Primary care physicians prescribe antithrombotic therapy less often than cardiologists, which is one of the reasons for this underutilization.

Aged↗
PubMed1999

Practical management of atrial fibrillation.

Atrial fibrillation (AF) is a common cardiac arrhythmia that becomes more common as patients get older. We review the common factors associated with AF and hemodynamic abnormalities. In addition, we discuss practical management issues concerning treatment of patients with rapid, hemodynamically significant AF, as well as patients with hemodynamically stable AF. The strategies of rhythm control and rate control and the different modalities available for use with each strategy are presented. Issues related to stroke prevention in AF are reviewed.

Atrial Fibrillation↗
PubMed1998

Inflammation, pravastatin, and the risk of coronary events after myocardial infarction in patients with average cholesterol levels. Cholesterol and Recurrent Events (CARE) Investigators.

BACKGROUND: We studied whether inflammation after myocardial infarction (MI) is a risk factor for recurrent coronary events and whether randomized treatment with pravastatin reduces that risk. METHODS AND RESULTS: A nested case-control design was used to compare C-reactive protein (CRP) and serum amyloid A (SAA) levels in prerandomization blood samples from 391 participants in the Cholesterol and Recurrent Events (CARE) trial who subsequently developed recurrent nonfatal MI or a fatal coronary event (cases) and from an equal number of age- and sex-matched participants who remained free of these events during follow-up (control subjects). Overall, CRP and SAA were higher among cases than control subjects (for CRP P=0.05; for SAA P=0.006) such that those with levels in the highest quintile had a relative risk (RR) of recurrent events 75% higher than those with levels in the lowest quintile (for CRP RR= 1.77, P=0.02; for SAA RR= 1.74, P=0.02). The study group with the highest risk was that with consistent evidence of inflammation (elevation of both CRP and SAA) who were randomly assigned to placebo (RR=2.81, P=0.007); this risk estimate was greater than the product of the individual risks associated with inflammation or placebo assignment alone. In stratified analyses, the association between inflammation and risk was significant among those randomized to placebo (RR=2.11, P=0.048) but was attenuated and nonsignificant among those randomized to pravastatin (RR=1.29, P=0.5). CONCLUSIONS: Evidence of inflammation after MI is associated with increased risk of recurrent coronary events. Therapy with pravastatin may decrease this risk, an observation consistent with a nonlipid effect of this agent.

Aged↗
PubMed1998

Comparison of right- and left-sided pectoral implantation parameters with the Jewel active can cardiodefibrillator. The World Wide Jewel Investigators.

A total of 1,207 patients received a Medtronic Jewel active can ICD (models 7218C, 7219C), with a Transvene lead in 97 centers in Europe and North America. Nineteen implants were from the right pectoral region. Patients with right-sided ICDs did not differ in terms of mean age, % male, left ventricular ejection fraction, New York Heart Association Functional Class, antiarrhythmic drug therapy, indication for the implantable cardioverter defibrillator, and R wave values at implantation, but tended to have slightly higher pacing thresholds (1.2 +/- 0.5 V vs 1.0 +/- 0.6 V, P = 0.012) and higher defibrillation thresholds (14.7 +/- 6.4 J vs 11.5 +/- 6 J, P = 0.11) compared with patients with left sided implants. Patients with right-sided implants had a longer implantation time compared with patients with left-sided implants (118 +/- 70 minutes vs 91 +/- 46 minutes, P = 0.074). In follow-up, 5 patients with right-sided implantation received successful therapy for either ventricular fibrillation, (8 episodes) or ventricular tachycardia (5 episodes). No ineffective therapy from the device was delivered in any patients with right-sided implantation. Right-sided pectoral implants are feasible with the Medtronic Jewel active can ICD.

Adult↗
PubMed1997

Sphygmomanometrically determined pulse pressure is a powerful independent predictor of recurrent events after myocardial infarction in patients with impaired left ventricular function. SAVE investigators. Survival and Ventricular Enlargement.

BACKGROUND: There is increasing evidence of a link between conduit vessel stiffness and cardiovascular events, although the association has never been tested in a large post-myocardial infarction patient population. METHODS AND RESULTS: We evaluated the relationship between baseline pulse pressure, measured by sphygmomanometry 3 to 16 days after myocardial infarction, and subsequent adverse clinical events in the 2231 patients enrolled in the SAVE Trial. Increased pulse pressure was associated with increased age, left ventricular ejection fraction, female sex, history of prior infarction, diabetes, and hypertension and use of digoxin and calcium channel blockers. Over a 42-month period, there were 503 deaths, 422 cardiovascular deaths, and 303 myocardial infarctions. Pulse pressure was significantly related to each of these end points as a univariate predictor. In a multivariate analysis, pulse pressure remained a significant predictor of total mortality (relative risk, 1.08 per 10 mm Hg increment in pulse pressure; 95% CI, 1.00 to 1.17; P<.05) and recurrent myocardial infarction (relative risk, 1.12; 95% CI, 1.01 to 1.23; P<.05) after control for age; left ventricular ejection fraction; mean arterial pressure; sex; treatment arm (captopril or placebo); smoking history; history of prior myocardial infarction, diabetes, or hypertension; and treatment with beta-blockers, calcium channel blockers, digoxin, aspirin, or thrombolytic therapy. CONCLUSIONS: These data provide strong evidence for a link between pulse pressure, which is related to conduit vessel stiffness, and subsequent cardiovascular events after myocardial infarction in patients with left ventricular dysfunction.

Adult↗
PubMed1997

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.

Aged↗
PubMed1997

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.

Adult↗
PubMed1996

Electrophysiologic differences in young patients with atrial fibrillation. Influence of preexcitation.

Paroxysmal atrial fibrillation is a common arrhythmia, which may occur in young patients without known structural heart disease, with or without preexcitation. Elimination of an accessory pathway in these patients may prevent not only orthodromic and antidromic tachycardia but also atrial fibrillation. However, abnormalities of atrial conduction and refractoriness have been reported, suggesting that atrial fibrillation may still recur in these patients. In a review of all electrophysiologic studies performed at the authors' institution since January 1990 in patients under age 60 years of age without identifiable heart disease, 24 patients with atrial fibrillation were identified whose electrophysiologic measurements of a right atrial conduction and effective refractory period of the right atrium and accessory pathway were in sinus rhythm. Of these patients, 12 had preexcitation and the other 12 did not. These patients were compared with age- and sex-matched control subjects, 12 with preexcitation without atrial fibrillation and 13 without preexcitation or atrial fibrillation, respectively. Electrophysiologic abnormalities were noted in patients with atrial fibrillation depending on the presence or absence of preexcitation. In patients with preexcitation, these abnormalities were a shorter refractory period of the right atrium (212 +/- 33 ms) and of the accessory pathway (251 +/- 27 ms), compared with control subjects (241 +/- 27 ms, P < .05 and 306 +/- 61 ms, P < .02, respectively). In patients without preexcitation, conduction abnormality in the form of prolonged atrial conduction time when compared with control subjects (48 +/- 26 ms vs 31 +/- 10 ms, P < .05) was noted. These findings may influence the type of antiarrhythmic drug used in these patients, and if confirmed in a larger study, they may lead to a better understanding of factors influencing the development of atrial fibrillation in young patients.

Adult↗