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Biomedical subjects

K B Davis

Publications and source records attributed to K B Davis.

At least 55 records · Page 3Linked to original sources
PubMed1990

Ten-year follow-up of survival and myocardial infarction in the randomized Coronary Artery Surgery Study.

The Coronary Artery Surgery Study (CASS) randomized 780 patients to an initial strategy of coronary surgery or medical therapy. Of medically randomized patients, 6% had surgery within 6 months and a total of 40% had surgery by 10 years. At 10 years, there was no difference in cumulative survival (medical, 79% vs. surgical, 82%; NS) and no difference in percentage free of death and nonfatal myocardial infarction (medical, 69% vs. surgical, 66%; NS). Patients with an ejection fraction of less than 0.50 exhibited a better survival with initial surgery treatment (medical, 61% vs. surgical, 79%; p = 0.01). Conversely, patients with an ejection fraction greater than or equal to 0.50 exhibited a higher proportion free of death and myocardial infarction with initial medical therapy (medical, 75% vs. surgical, 68%; p = 0.04) although long-term survival remained unaffected (medical, 84% vs. surgical, 83%; p = 0.75). There were no significant differences either in survival and freedom from nonfatal myocardial infarction, whether stratified on presence of heart failure, age, hypertension, or number of vessels diseased. Thus, 10-year follow-up results confirm earlier reports from CASS that patients with left ventricular dysfunction exhibit long-term benefit from an initial strategy of surgical treatment. Patients with mild stable angina and normal left ventricular function randomized to initial medical treatment (with an option for later surgery if symptoms progress) have survival equivalent to those patients randomized to initial surgery.

Coronary Artery Bypass↗
PubMed1989

Early versus late hospital arrival for acute myocardial infarction in the western Washington thrombolytic therapy trials.

In the 3 Western Washington thrombolytic therapy trials, 54.9% of patients with acute myocardial infarction arrived at the hospital within 2 hours of symptom onset. These early arrivers were younger and more likely to be hypotensive and in cardiogenic shock than were patients arriving later. There were decreases in the time from symptom onset to hospital arrival (p = 0.0002) and in the time from hospital arrival to institution of thrombolytic therapy (p less than 0.0001) in the 8 hospitals that participated in both the Western Washington intravenous streptokinase and tissue plasminogen activator trials from 1983 to 1988. For those patients receiving thrombolysis, early arrival was associated with increased survival (p = 0.031) after adjustment by Cox regression analysis for important clinical predictors of long-term survival. These covariates included pulmonary edema, anterior wall acute myocardial infarction, hypotension and absence of chest pain at hospital arrival. Reductions in barriers to timely administration of thrombolytic therapy can be achieved and can result in improved survival.

Aged↗
PubMed1989

Survival patterns in clinical and angiographic subsets of medically treated patients with combined proximal left anterior descending and proximal left circumflex coronary artery disease (CASS).

Baseline, clinical, and angiographic features of 1014 Coronary Artery Surgery Study (CASS) registry patients with combined proximal left anterior descending and proximal left circumflex coronary disease were examined to define determinants of prognosis in this clinical high-risk patient subset. A stepwise Cox regression analysis identified congestive heart failure score, left ventricular contraction score, mitral regurgitation, age, and digitalis usage as independent variables predictive of 8-year survival. When patients were stratified by left ventricular contraction score, the 8-year survival rate was 62%, 49%, and 19%, respectively, for patients with a left ventricular score of 5 to 9, 10 to 14, and greater than or equal to 15 (p less than 0.0001). The presence of a stenosis greater than or equal to 70% in the right coronary artery was associated with worse survival (47% versus 54% at 8 years; p = 0.051). In conclusion, the diagnosis of combined proximal left anterior descending and left circumflex coronary artery disease represents a large prognostic spectrum that needs to be considered when counselling individual patients.

Coronary Angiography↗
PubMed1989

Asymptomatic left main coronary artery disease in the Coronary Artery Surgery Study (CASS) registry.

Left main coronary artery disease (i.e., greater than or equal to 50% stenosis) was found in 1,477 of 20,137 patients in the Coronary Artery Surgery Study (CAS) registry. Of these patients, 53 (3.6%) were asymptomatic. Asymptomatic and symptomatic patients were similar in regard to 1) severity of left main coronary artery stenosis (67% vs. 70%), 2) extent of proximal coronary artery disease (no differences in number of or severity of proximal stenoses), 3) left ventricular end-diastolic pressure (13 mm Hg vs. 14 mm Hg), 4) left ventricular wall motion score 9.1 vs. 8.7), and 5) number of coronary artery segments with greater than 70% stenosis (4.4 vs. 4.8). Among the asymptomatic patients, 47% received medical and 49% received surgical treatment. In the symptomatic group, 20% received medical and 78% received surgical therapy. The survival rate 5 years after surgery for treatment of left main coronary artery stenosis was 84% for the symptomatic patients and 88% for the asymptomatic patients (p = NS). Medical management of left main coronary artery disease produced a 5-year survival rate of 57% for asymptomatic patients and 58% for symptomatic patients. Within the asymptomatic subgroup, 88% of those surgically treated survived 5 years, whereas only 57% of those medically treated survived 5 years (p = 0.02). Thus, for CASS patients with left main coronary artery disease, the percentage of those that were asymptomatic is low (3.6%); asymptomatic and symptomatic patients with left main coronary artery disease had no significant difference in severity of left main coronary artery stenosis, extent of overall coronary artery disease, or left ventricular function.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Angiography↗
PubMed1989

Neurobehavioral outcomes in cardiac operations. A prospective controlled study.

To assess the severity and duration of new organic brain dysfunction after cardiac operations, we used an extensive battery of neuropsychologic tests to evaluate 65 patients undergoing coronary artery bypass grafting and 25 patients undergoing intracardiac operations with cardiopulmonary bypass. Patients were tested the day before the operation, before discharge from the hospital, and approximately 7 months later. Compared to 47 nonsurgical control subjects tested at comparable time intervals, surgical subjects showed generalized impairment of neuropsychologic abilities near the time of discharge from the hospital. At follow-up testing, there was no evidence of residual impairment among the surgically treated patients as a whole. In fact, they showed greater improvement compared to initial test scores than did control subjects. However, performance of 10 patients (11%) declined on half of the neuropsychologic variables between preoperative and follow-up testing. Neurobehavioral outcome was not related to the type of operation (coronary bypass versus intracardiac), to factors of cardiopulmonary bypass (duration, aortic occlusion time, hypotension, arterial carbon dioxide tension, minimum hematocrit value, minimum temperature). The only predictor of negative outcome was advanced age. We conclude that, although neurobehavioral impairment is common during hospitalization after cardiac operations, the prognosis for eventual full recovery is favorable, although less so among the elderly.

Anxiety↗
PubMed1988

Clinical assessment of a flow-through fluorometric blood gas monitor.

We performed an observational study to evaluate a flow-through fluorometric instrument (Gas-STAT) that continuously measures the carbon dioxide tension (PCO2), oxygen tension (PO2), and pH of blood in the cardiopulmonary bypass circuit. Setup and calibration of the instrument typically required 20 minutes. During bypass, 129 blood samples were drawn from 16 patients for comparison with conventional measurements obtained with a blood gas machine. Data for each variable, within each sensor, were analyzed by linear regression. The ranges of the standard errors of the estimate were 0.7 to 4.2 mm Hg for PCO2, 18.3 to 78.7 mm Hg for the high PO2 range, 1.4 to 7.1 mm Hg for the low PO2 range, and 0.008 to 0.049 for pH. The regression lines differed from the identity line (P less than 0.05) in at least one variable in most patients, and large deviations from the line of identity in both slope and intercept were common. Among 58 sensors evaluated, failures occurred in 5 (2.9%) of the 174 optodes, and minor leakage occurred in 2 (3.4%) of the flow-through cells. We conclude that although this flow-through fluorometric instrument is an adequate monitor of trends in blood gases during cardiopulmonary bypass, it is not accurate enough to supplant conventional laboratory measurements.

Blood Gas Analysis↗
PubMed1988

Relation of global and regional left ventricular function to tomographic thallium-201 myocardial perfusion in patients with prior myocardial infarction.

To determine the relation between regional myocardial perfusion and regional wall motion in humans, tomographic thallium-201 imaging and two-dimensional echocardiography at rest were performed on the same day in 83 patients 4 to 12 weeks after myocardial infarction. Myocardial perfusion and wall motion were assessed independently in five left ventricular regions (total 415 regions). Regional myocardial perfusion was quantitated as a percent of the region infarcted (range 0 to 100%) using a previously validated method. Wall motion was graded on a four point scale as 1 = normal (n = 266 regions), 2 = hypokinesia (n = 64), 3 = akinesia (n = 70), 4 = dyskinesia (n = 13) or not evaluable (n = 2). Regional wall motion correlated directly with the severity of the perfusion deficit (r = 0.68, p less than 0.0001). Among normally contracting regions, the mean perfusion defect score was only 2 +/- 4. Increasingly severe wall motion abnormalities were associated with larger perfusion defect scores (hypokinesia = 6 +/- 5, akinesia = 11 +/- 7 and dyskinesia = 18 +/- 5, all p less than 0.01 versus normal. Among regions with normal wall motion, only 3% had a perfusion defect score greater than or equal to 10. Conversely, among 68 regions with a large (greater than or equal to 10) perfusion defect, only 13% had normal motion whereas 87% had abnormal wall motion. The relation between perfusion and wall motion noted for the entire cohort was also present in subgroups of patients with anterior or inferior infarction. In patients with prior myocardial infarction, the severity of the tomographic thallium perfusion defect correlates directly with echocardiographically defined wall motion abnormalities, both globally and regionally.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1988

The prevalence of steal-prone coronary anatomy in patients with coronary artery disease: an analysis of the Coronary Artery Surgery Study Registry.

Coronary steal requires a specific anatomic arrangement of coronary occlusion, collateral vessels, and stenosis of the artery supplying the collaterals. The prevalence of this anatomic variant, steal-prone coronary anatomy, was investigated in 16,249 patients with coronary artery disease whose angiograms were carefully recorded as part of the Coronary Artery Surgery Study (CASS). Almost half of the angiograms had one or more total occlusions, and, of these, about 80% had angiographically visible collateral supply to the area distal to the occlusion. Of subjects with an occlusion and collaterals, about 60% had a hemodynamically significant stenosis of the artery supplying the collateral vessels. In summary, 23% of the patients in the CASS Registry demonstrated steal-prone coronary anatomy. Thus, coronary steal could possibly affect almost a quarter of the patients with coronary artery disease having anesthesia. Studies that seek clinical evidence of harm from coronary steal must be done in that subset of patients with coronary artery disease with steal-prone anatomy.

Angiography↗
PubMed1988

The Western Washington Intravenous Streptokinase in Acute Myocardial Infarction Randomized Trial.

Three hundred sixty-eight patients were randomly assigned to receive intravenous streptokinase (IVSK) (n = 191) or standard therapy (n = 177) to determine the efficacy of IVSK in the treatment of acute myocardial infarction. The mean time to treatment was 3.5 hr. At 14 days there were 12 deaths in the treatment group (6.3%) and 17 deaths in the control group (9.6%) (p = .23). Early mortality was related to infarct location. Fourteen day mortality for anterior infarctions was 10.4% for treatment with IVSK and 22.4% for control patients (p = .06) and was similar for IVSK-treated patients with inferior infarctions, 4.0% vs 1.8% (p = .32). For those randomized under 3 hr, 14 day mortality tends to be lower in treated patients, 5.2% vs 11.5% (p = .11). There was significant improvement in long-term survival for patients with anterior infarction; 2 year survival was 81% for IVSK-treated patients and 65% for control patients (p = .05). There was no improvement in survival for patients with inferior myocardial infarction (p = .27). We conclude that patients with anterior myocardial infarction have improved survival when treated within the first 6 hr of symptoms. Patients with inferior infarction do not appear to have improved survival with thrombolytic therapy. Some of this improvement in survival in patients with anterior infarction may be due to a higher frequency of revascularization procedures in the treatment group.

Aged↗
PubMed1988

Clinical implications of internal mammary artery bypass grafts: the Coronary Artery Surgery Study experience.

From the Coronary Artery Surgery Study Registry, all patients undergoing initial bypass surgery procedures with independent vein grafts were identified. The 950 patients receiving an internal mammary artery bypass graft were compared with the 6027 patients receiving vein graft alone. Improved survival rates with internal mammary artery grafts were noted at hospitals in which these grafts were performed infrequently as well as those in which the internal mammary artery graft was used frequently. The improved survival was noted in patients with normal (p = .004) as well as impaired (p = .004) ventricular function, in men (p = .0001) as well as women (p = .005), in patients over age 65 (p = .01) as well as younger patients (p less than .0001), and in those with (p = .05) or without (p less than .0001) critical stenosis of the left main coronary artery. The internal mammary artery bypass graft was an independent predictor of survival (p = .0004) and reduced the risk of dying by a factor of 0.64. It was concluded that the internal mammary artery graft is the bypass vessel of choice and should not be denied any subgroup.

Blood Vessel Prosthesis↗
PubMed1988

Intravenous streptokinase for acute myocardial infarction. Effects on global and regional systolic function.

The Western Washington Intravenous Streptokinase Trial randomized 368 patients with acute myocardial infarction to receive either intravenous streptokinase or standard therapy. The ventriculograms and coronary angiograms obtained in 170 patients 10.4 +/- 7.4 days after infarction were analyzed to evaluate the effects of thrombolytic therapy on global and regional systolic function. Streptokinase treatment resulted in a higher patency rate of the infarct-related artery (68.5%) than did standard therapy (44.8%) (p = 0.003). Ejection fraction was higher in streptokinase-treated patients (54% vs. 51%, p = 0.056), and the difference was most marked in patients with anterior myocardial infarction (53% vs. 44%, p = 0.03). Regional wall motion was measured by the centerline method and expressed in mean +/- SD motion in 52 normal subjects. There was a trend toward better function of the infarct zone in streptokinase-treated patients (SD, -2.48 vs. -2.70, p = 0.24). Additionally, streptokinase-treated patients had significantly better wall motion of noninfarct areas (SD, 0.36 vs. -0.08, p = 0.02). Treatment effects on function of noninfarct regions were most apparent in the subset of patients with multivessel disease. Thus, intravenous streptokinase preserves left ventricular function in patients with acute myocardial infarction. This benefit includes favorable effects on the function of regions remote from the site of infarction.

Cardiac Catheterization↗
PubMed1987

Features of cardiac arrest episodes with and without acute myocardial infarction in the Coronary Artery Surgery Study (CASS).

Angiographic evidence of coronary artery disease was present in 16,002 patients in the Coronary Artery Surgery Study (CASS) registry. Of these patients, 551 had a history of cardiac arrest before enrollment angiography. Cardiac arrest was a complication of acute myocardial infarction (AMI) in 372 patients (68%). Electrocardiographic documentation of the responsible rhythm was available in 283 patients. Ventricular fibrillation (VF) was present in 112 (60%), ventricular tachycardia (VT) in 41 (22%) and both VT and VF in 26 (14%) patients. Stepwise linear discriminant analysis comparing the 551 cardiac arrest patients with the other 15,451 patients selected left ventricular wall motion score (F = 265), use of digitalis (F = 71), impaired blood supply to any segment (F = 16) and particularly to the anterior wall (F = 11) as discriminating variables associated with cardiac arrest. Patients with cardiac arrest occurring as a complication of AMI were younger (F = 12), had greater impairment of coronary blood supply (F = 7) and were more likely to be on a cholesterol-lowering diet (F = 16) than were patients with arrest remote from infarction. Comparison of patients with VT versus those with VF showed a positive association of VT with age (F = 8), a trend toward worse left ventricular function and presence of a left ventricular aneurysm, but no difference in severity and collateralization of coronary artery disease. It is concluded that cardiac arrest is related to the extent of myocardial damage.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1986

Risk of noncardiac operation in patients with defined coronary disease: The Coronary Artery Surgery Study (CASS) registry experience.

It has been suggested that coronary artery bypass grafting (CABG) is efficacious in patients with severe coronary artery disease before they undergo a major noncardiac operation. The Coronary Artery Surgery Study (CASS) registry population was reviewed to identify variables affecting operative mortality and cardiovascular morbidity for noncardiac procedures, and to assess the influence of prior CABG on these surgical risks. Major noncardiac operations were performed on 1,600 registry patients between June 30, 1978, and June 30, 1981. Operative mortality for individuals without significant coronary artery disease (Group 1) was 0.5% (2/399) and for patients with such disease having CABG prior to a noncardiac procedure (Group 2), it was 0.9% (7/743) (Group 1 versus Group 2, p = 0.42). Patients with significant coronary artery disease undergoing noncardiac operation without prior CABG (Group 3) had an increased operative mortality, 2.4% (11/458) (p = 0.009). Group 2 patients had more severe angina symptoms (p less than 0.001) and more extensive coronary artery disease (p less than 0.001) on entering CASS than Group 3 patients. Postoperative chest pain occurred in 8.7% (40/458) of the Group 3 patients versus 4.5% (18/399) in Group 1 and 5.1% (38/743) in Group 2 (p = 0.004). No group differences were noted for the incidence of perioperative myocardial infarction or arrhythmias.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Should airline pilots be eligible to resume active flight status after coronary bypass surgery?: a CASS registry study.

Medical certification to return to work after coronary bypass surgery in occupations that carry a risk to public safety is controversial, particularly for airline pilots. To address this issue, 10,312 patients from the CASS registry who underwent coronary bypass surgery were studied and 2,326 men with clinical and postoperative characteristics similar to those of the average airline pilot who might apply to renew his license after surgery were selected. The 5 year probability of remaining free of an acute cardiac event, defined as acute coronary insufficiency, myocardial infarction or sudden death, was 0.92 +/- 0.01 (mean +/- SE) for the 1,207 men without previous myocardial infarction and 0.98 +/- 0.01 for the 122 men who never smoked and did not have a history of hypertension. Among the 1,119 men with a previous myocardial infarction, the probability of remaining free of acute cardiac events was 0.91 +/- 0.02 and 0.92 +/- 0.02 when left ventricular contraction score was 5 to 9 and 10 or greater, respectively. In this patient subgroup, mortality rate was similar to that of the age-matched U.S. male population when the left ventricular contraction score was 5 to 9 (4.0% versus 4.3%; p = NS) but significantly worse when the left ventricular contraction score was 10 or greater (7% versus 4.2%; p = 0.05). The data from this CASS registry study are pertinent to the question of operationally unlimited first-class medical certification of carefully selected airline pilots after coronary bypass surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

The effect of medical and surgical treatment on subsequent sudden cardiac death in patients with coronary artery disease: a report from the Coronary Artery Surgery Study.

The effect of medical and surgical treatment on subsequent sudden cardiac death was assessed in 13,476 patients in the Coronary Artery Surgery Study registry who had significant coronary artery disease, operable vessels, and no significant valvular disease. (Patients were assigned to medical or surgical therapy on the basis of clinical judgment and not according to a randomization scheme; therefore, biases associated with unknown variables could not be evaluated.) Sudden cardiac death occurred in 452 patients (3.4%) during a mean follow-up of 4.6 years. Five year survival free of sudden death for medically treated patients was 94 +/- 0.3%, and that for surgically treated patients was 98 +/- 0.2% (p less than .0001). Twelve baseline clinical, electrocardiographic, and angiographic variables were significantly different between patients alive at the last follow-up and those suffering sudden death. Data on these variables were available for 11,508 patients. Sudden death occurred in 257 (4.9%) of 5258 medically treated and 101 (1.6%) of 6250 surgically treated patients. In a high-risk patient subset with three-vessel disease and history of congestive heart failure, 91% of surgically treated patients had not suffered sudden death compared with 69% of medically treated patients. After Cox survival analysis was used to correct for baseline variables, surgical treatment had an independent effect on sudden death (p less than .0001). This reduction was most pronounced in high-risk patients.

Coronary Artery Bypass↗
PubMed1986

The influence of surgery on the natural history of angiographically documented left ventricular aneurysm: the Coronary Artery Surgery Study.

Coronary artery bypass surgery with or without aneurysmectomy has been used to treat patients with angiographically defined left ventricular aneurysm. To evaluate whether surgery benefits such patients, we analyzed the data from 1131 patients who were enrolled in the registry of the Coronary Artery Surgery Study. Four hundred sixty-seven patients underwent bypass surgery, of which 238 also had left ventricular resection, and 30 had resection alone. The overall operative mortality was 7.9%; the operative mortality was 7% for bypass alone compared with 9% for bypass surgery plus left ventricular resection (NS). Long-term survival by life-table analysis was similar for both medically and surgically treated patients (69% vs 67%, respectively). Cox survival analysis identified congestive heart failure score, duration of chest pain, extent of coronary disease, left ventricular end-diastolic pressure, age, and surgical therapy as important predictors of outcome. Patient subsets that showed improved survival with surgical therapy after adjustment for inequities in baseline characteristics were patients with three-vessel disease and those patients in moderate- and high-risk subgroups. Surgical therapy significantly reduced symptoms of angina and use of cardiac medications but the incidence of recurrent infarction was similar for both therapies.

Age Factors↗
PubMed1986

The role of coronary bypass surgery for 'left main equivalent' coronary disease: the Coronary Artery Surgery Study registry.

Combined proximal left anterior descending and proximal left circumflex, or "left main equivalent" (LMEQ), disease defines a prognostic angiographic high-risk patient population. We assessed the effect of coronary bypass surgery compared with medical therapy in 903 patients with LMEQ disease by stratified life table and Cox regression analysis. The 5 year survival rates of the 639 and 264 patients who received surgical vs medical therapy was 85% vs 55%, respectively (p less than .001). Analysis of patient subsets stratified by age, angina class, right coronary disease, and ejection fraction revealed a significant survival benefit for surgically treated patients in most strata. Cox regression analysis revealed improved survival for surgically treated patients after adjustment for important baseline variables known to influence prognosis. Surgically treated patients had significantly less angina and need for antianginal drugs compared with the medically treated group. When the Coronary Artery Surgery Study randomized and randomizable LMEQ patients were analyzed, coronary bypass surgery improved 5 year survival when preoperative ejection fraction was under 0.50 but not when ejection fraction was 0.50 or higher. Thus coronary bypass surgery prolongs and improves quality of life (as defined by angina status and need for antianginal drugs) in most patients with LMEQ disease but does not appear to improve 5 year survival in a small subset of LMEQ patients who are asymptomatic after myocardial infarction or who have mild chronic stable angina and are under age 65 with well-preserved left ventricular function.

Aged↗