Biomedical subjects

B Marchant

Publications and source records attributed to B Marchant.

At least 19 recordsLinked to original sources

PubMed2001

Efficacy of dofetilide in the treatment of atrial fibrillation-flutter in patients with reduced left ventricular function: a Danish investigations of arrhythmia and mortality on dofetilide (diamond) substudy.

BACKGROUND: In patients with left ventricular dysfunction, atrial fibrillation and flutter (AF and AFl, respectively) are common arrhythmias associated with increased morbidity and mortality. The present study investigated the potential of dofetilide in AF-AFl patients with left ventricular dysfunction to restore and maintain sinus rhythm, which might reduce mortality and hospitalizations. METHODS AND RESULTS: In the Danish Investigations of Arrhythmia and Mortality ON Dofetilide (DIAMOND) studies, 506 patients were in AF-AFl at baseline. Over the course of study, cardioversion occurred in 148 (59%) dofetilide- and 86 (34%) placebo-treated patients. In these patients, the probability of maintaining sinus rhythm for 1 year was 79% with dofetilide versus 42% with placebo (P<0.001). Dofetilide had no effect on all-cause mortality, but restoration and maintenance of sinus rhythm was associated with significant reduction in mortality (risk ratio [RR], 0.44; 95% CI, 0.30 to 0.64; P<0.0001). In addition, dofetilide therapy was associated with a significantly lower risk ratio versus placebo for either all-cause (RR, 0.70; 95% CI, 0.56 to 0.89; P</=0.005) or congestive heart failure (RR, 0.69; 95% CI, 0.51 to 0.93; P</=0.02) rehospitalization. CONCLUSIONS: Dofetilide is safe and increases the probability of obtaining and maintaining sinus rhythm in patients with structural heart disease. The present study suggests that restoration of sinus rhythm is associated with improved survival.

Administration, Oral↗

PubMed2001

Screening of a HUVEC cDNA library with transplant-associated coronary artery disease sera identifies RPL7 as a candidate autoantigen associated with this disease.

A HUVEC cDNA library was screened with sera from two patients who had developed transplant-associated coronary artery disease (TxCAD) following cardiac transplantation. A total of six positive clones were isolated from a primary screen of 40 000 genes. Subsequent DNA sequence analysis identified these to be lysyl tRNA synthetase, ribosomal protein L7, ribosomal protein L9, beta transducin and TANK. Another gene whose product could not be identified showed homology to a human cDNA clone (DKFZp566M063) derived from fetal kidney. Full-length constructs of selected genes were expressed as his-tag recombinant fusion proteins and used to screen a wider patient base by ELISA to determine prevalence and association with TxCAD. Of these ribosomal protein L7 showed the highest prevalence (55.6%) with TxCAD sera compared to 10% non-CAD.

Adult↗

PubMed2001

Analysis of the physician variable in pain management.

BACKGROUND: The role of physician variability in pain management is unknown. OBJECTIVE: To assess the role of physician variability in the management of pain and provide quantitative data regarding the status of pain management in Michigan. DESIGN: A multi-item mail survey was used to determine the physician's perceived knowledge of pain management modalities, goals, satisfaction, and confidence with pain treatment. Participants. The focus of this report was a group of 368 licensed Michigan physicians who provide clinical care. RESULTS: Overall, 30% of the study group reported no formal education in pain management, although younger physicians reported more education (correlation coefficient = -0.252, P <.001). The physicians reported greater confidence in their knowledge of meperidine than other Schedule II opioids (P <.001 ). In regards to the opinion that prescribing strong opioids would attract a medical review, the physician responses ranged from 1 (strongly disagree) to 5 (strongly agree). The median score for this scale was 4, accounting for 46% of the responses. The study group expressed less satisfaction with their treatment of chronic pain as well as lower goals for relief (mean: 3.8; 95% confidence interval: 3.7-3.9). CONCLUSIONS: Lower expectations for relief and less satisfaction in its management may contribute to the undertreatment of chronic pain. Perceptions of regulatory scrutiny may contribute to suboptimal pain management. These preliminary data highlight physician variability in pain decision making while providing insights into educational needs.

Journal Article↗

PubMed2000

Effect of dofetilide in patients with recent myocardial infarction and left-ventricular dysfunction: a randomised trial.

BACKGROUND: Arrhythmias cause much morbidity and mortality after myocardial infarction, but in previous trials, antiarrhythmic drug therapy has not been convincingly effective. Dofetilide, a new class III agent, was investigated for effects on all-cause mortality and morbidity in patients with left-ventricular dysfunction after myocardial infarction. METHODS: In 37 Danish coronary-care units, 1510 patients with severe left-ventricular dysfunction (wall motion index < or = 1.2, corresponding to ejection fraction < or = 0.35) were enrolled in a randomised, double-blind study comparing dofetilide (n=749) with placebo (n=761). The primary endpoint was all-cause mortality. Secondary endpoints included cardiac and arrhythmic mortality and total arrhythmic deaths. Analyses were by intention to treat. FINDINGS: No significant differences were found between the dofetilide and placebo groups in all-cause mortality (230 [31%] vs 243 [32%]), cardiac mortality (191 [26%] vs 212 [28%]), or total arrhythmic deaths (129 [17%] vs 140 [18%]). Atrial fibrillation or flutter was present in 8% of the patients at study entry. In these patients, dofetilide was significantly better than placebo at restoring sinus rhythm (25 of 59 vs seven of 56; p=0.002). There were seven cases of torsade de pointes ventricular tachycardia, all in the dofetilide group. INTERPRETATION: In patients with severe left-ventricular dysfunction and recent myocardial infarction, treatment with dofetilide did not affect all-cause mortality, cardiac mortality, or total arrhythmic deaths. Dofetilide was effective in treating atrial fibrillation or flutter in this population.

Adult↗

PubMed2000

Role of platelet-derived growth factor as an adjunct to surgery in the management of pressure ulcers.

Management options for pressure ulcers include local wound care, surgical repair, and, more recently, topical application of platelet-derived growth factor (PDGF). PDGF is a glycoprotein that is mitogenic for mesenchymal cells and has been studied extensively for applicability in promoting the healing of chronic human wounds. Using data obtained from a multicenter clinical trial for the treatment of full-thickness pressure ulcers, a subset analysis was performed to investigate the outcome of salvage surgery for pressure ulcers, after incomplete closure occurred with the topical use of either recombinant human PDGF-BB (rhPDGF-BB) or placebo gel. At the University of Michigan Wound Care Center, subset data from a randomized, double-blind, placebo-controlled, parallel group clinical trial were reviewed to compare the effects of three concentrations of rhPDGF-BB on full-thickness pressure ulcers of the trunk with those of the placebo. Twenty-eight patients were enrolled and 27 completed the trial. An intent-to-treat analysis was used to evaluate data. If the ulcer did not heal by the end of the 16-week trial period, the surgeon, still blinded to the treatment group, offered salvage surgical repair of the pressure ulcer. Eleven patients underwent salvage surgical repair using myocutaneous flaps, primary closure, or skin grafts. Of three patients who received placebo followed by surgery, none progressed to full healing within 1 year. Of 12 patients in the treatment group who received rhPDGF-BB and salvage surgery, 11 (92 percent) ultimately healed the ulcers within 1 year after the start of the clinical trial. These findings suggest that treatment with rhPDGF-BB before surgery enhances the ability to achieve a closed wound over surgery alone. It must yet be determined to what degree rhPDGF-BB contributed to the excellent results seen in the rhPDGF-BB/surgery group. It is possible that rhPDGF-BB "primes" the local wound milieu to make it more responsive to complete closure following surgical treatment.

Adult↗

PubMed2000

Autonomic dysfunction is related to impaired pancreatic beta cell function in patients with coronary artery disease.

OBJECTIVE: To assess the role of beta cell failure in the development of autonomic dysfunction in patients with coronary artery disease. DESIGN: Autonomic function was measured by standard clinical methods and by heart rate variability in 24 type II diabetic and 24 non-diabetic subjects with coronary artery disease. Quantitative estimates of pancreatic beta cell function (%beta) and insulin resistance were made from basal plasma glucose and insulin concentrations using a computer solved model. Fasting proinsulin levels provided an independent measure of beta cell function. RESULTS: The circadian rhythm of sympathovagal balance (ratio of low to high frequency spectral components of heart rate variability) was significantly attenuated in patients with below median (%beta </= 63. 3) compared with above median pancreatic beta cell function. Multiple measures of autonomic function showed positive associations with %beta (low frequency: r = 0.41, p = 0.004; high frequency: r = 0.27, p = 0.07; lying/standing fall in systolic pressure: r = -0.30, p = 0.04) and negative associations with proinsulin (low frequency: r = -0.35, p = 0.03; high frequency: r = -0.36, p = 0.02; standard deviation of RR intervals: r = -0.43, p = 0.007). Associations tended to be stronger in non-diabetic than diabetic patients. In contrast, there was no association between insulin resistance and either autonomic function or the circadian rhythm of sympathovagal balance, regardless of diabetes status. CONCLUSIONS: The data are consistent with the hypothesis that beta cell failure plays a pathogenic role in the development of autonomic dysfunction in patients with coronary artery disease.

Adult↗

PubMed1999

Dofetilide in patients with congestive heart failure and left ventricular dysfunction. Danish Investigations of Arrhythmia and Mortality on Dofetilide Study Group.

BACKGROUND: Atrial fibrillation occurs frequently in patients with congestive heart failure and commonly results in clinical deterioration and hospitalization. Sinus rhythm may be maintained with antiarrhythmic drugs, but some of these drugs increase the risk of death. METHODS: We studied 1518 patients with symptomatic congestive heart failure and severe left ventricular dysfunction at 34 Danish hospitals. We randomly assigned 762 patients to receive dofetilide, a novel class III antiarrhythmic agent, and 756 to receive placebo in a double-blind study. Treatment was initiated in the hospital and included three days of cardiac monitoring and dose adjustment. The primary end point was death from any cause. RESULTS: During a median follow-up of 18 months, 311 patients in the dofetilide group (41 percent) and 317 patients in the placebo group (42 percent) died (hazard ratio, 0.95; 95 percent confidence interval, 0.81 to 1.11). Treatment with dofetilide significantly reduced the risk of hospitalization for worsening congestive heart failure (risk ratio, 0.75; 95 percent confidence interval, 0.63 to 0.89). Dofetilide was effective in converting atrial fibrillation to sinus rhythm. After one month, 22 of 190 patients with atrial fibrillation at base line (12 percent) had sinus rhythm restored with dofetilide, as compared with only 3 of 201 patients (1 percent) given placebo. Once sinus rhythm was restored, dofetilide was significantly more effective than placebo in maintaining sinus rhythm (hazard ratio for the recurrence of atrial fibrillation, 0.35; 95 percent confidence interval, 0.22 to 0.57; P<0.001). There were 25 cases of torsade de pointes in the dofetilide group (3.3 percent) as compared with none in the placebo group. CONCLUSIONS: In patients with congestive heart failure and reduced left ventricular function, dofetilide was effective in converting atrial fibrillation, preventing its recurrence, and reducing the risk of hospitalization for worsening heart failure. Dofetilide had no effect on mortality.

Adult↗

PubMed1997

Attenuation or absence of circadian and seasonal rhythms of acute myocardial infarction.

OBJECTIVES: To examine the circadian, seasonal, and weekly rhythms of acute myocardial infarction, and to identify subgroups in whom the rhythms are attenuated or absent to provide further information about the mechanisms of the rhythms and the processes responsible for triggering plaque events. DESIGN AND SETTING: Prospective, observational study in a general hospital. PATIENTS AND METHODS: 1225 consecutive patients admitted to a coronary care unit with acute myocardial infarction were studied. Admission rates were calculated according to the hour of the day (circadian rhythm), day of the week (weekly rhythm), and month of year (seasonal rhythm). The data were analysed for variations within the whole group and within subgroups. RESULTS: A weekly rhythm of acute myocardial infarction could not be demonstrated but there was a trend towards higher admission rates at the beginning of the week. However, the time of onset of symptoms showed significant circadian variation for the group as a whole, peaking in the morning (P = 0.006), against an otherwise fairly constant background rate. Subgroup analysis showed complete absence of the circadian rhythm in patients who were diabetic, South Asian, or taking beta blockers or aspirin on admission. Significant seasonal variation in admission rates was also demonstrated for the group as a whole with a winter peak and a summer trough (P = 0.009). Again, no seasonal rhythm could be demonstrated in patients who were diabetic, South Asian, or taking beta blockers or aspirin on admission. CONCLUSIONS: The absence of circadian and seasonal rhythms of acute myocardial infarction in almost identical subgroups suggests that common mechanisms are involved in driving these rhythms. The autonomic nervous system is a likely candidate because the rhythms were absent in patients taking beta blockers as well as in patients in whom derangement of autonomic function commonly occurs.

Adrenergic beta-Antagonists↗

PubMed1996

Comparison of case fatality in south Asian and white patients after acute myocardial infarction: observational study.

OBJECTIVE: To compare mortality in south Asian (Indian, Pakistani, and Bangladeshi) and white patients in the six months after hospital admission for acute myocardial infarction. DESIGN: Observational study. SETTING: District general hospital in east London. PATIENTS: 149 south Asian and 313 white patients aged < 65 years admitted to the coronary care unit with acute myocardial infarction from 1 December 1988 to 31 December 1992. MAIN OUTCOME MEASURE: All cause mortality in the first six months after myocardial infarction. RESULTS: The admission rate in the south Asians was estimated to be 2.04 times that in the white patients. Most aspects of treatment were similar in the two groups, except that a higher proportion of the south Asians received thrombolytic drugs (81.2% v 73.8%). After adjustment for age, sex, previous myocardial infarction, and treatment with thrombolysis or aspirin, or both, the south Asians had a poorer survival over the six months from myocardial infarction (hazard ratio 2.02 (95% confidence interval 1.14 to 3.56), P = 0.018), but a substantially higher proportion were diabetic (38% v 11%, P < 0.001), and additional adjustment for diabetes removed much of their excess risk (adjusted hazard ratio 1.26 (0.68 to 2.33), P = 0.47). CONCLUSION: South Asian patients had a higher risk of admission with myocardial infarction and a higher risk of death over the ensuing six months than the white patients. The higher case fatality among the south Asians, largely attributable to diabetes, may contribute to the increased risk of death from coronary heart disease in south Asians living in Britain.

Adult↗

PubMed1995

Early discharge after acute myocardial infarction: risks and benefits.

BACKGROUND: Thrombolytic treatment reduces mortality in patients with acute myocardial infarction but is associated with recurrent thrombotic events after admission, and it is unclear whether current practices of early hospital discharge are safe. Timing of first major adverse events (death, reinfarction, unstable angina, secondary ventricular fibrillation) in the early post-infarction period was studied to determine the risks. DESIGN: Follow up study. PATIENTS: 608 consecutive patients (447 men and 161 women) with confirmed myocardial infarction who were admitted to the coronary care unit of a district general hospital between January 1989 and December 1991. Clinical details, including the development of left ventricular failure and in hospital adverse events, were recorded prospectively. Follow up for out of hospital adverse events was carried out by review of the case notes, postal questionnaire, and where necessary, by telephone contact with the patient and his general practitioner. RESULTS: The risk (95% confidence interval) of major adverse events in the first 10 days was 32.3% (26.3 to 39.4%) in patients with heart failure and 7.3% (5.1 to 9.2%) in those without. Smoothed estimates of the event rate in patients without heart failure decreased from 5.9 events/1000 persons/day on day 6 to 3.4 events/1000 persons/day on day 10 and 0.9 events/1000 persons/day on day 21. The corresponding cumulative risk estimates suggest that about 11 in every 1000 patients suffer a major, but often unpreventable, adverse event on day 6 or 7 after admission, and 23 in every 1000 do so between days 6 and 10. CONCLUSIONS: The point at which the risk to the individual becomes acceptably low is a matter of judgement, but the risk of a major adverse event declines rapidly after a heart attack, and particularly for patients without heart failure discharge within a few days may be appropriate. Prolonging stay unnecessarily may use resources which could be more effectively used to treat cardiac disease in other ways.

Adult↗

PubMed1995

Risks related to the introduction of exotic diseases: a European view.

The European Union (EU) has historically been free of a number of epidemic diseases of livestock and is approaching eradication of several others. This situation is put at risk by the importation of live animals and animal products. Animal products include products which are broadly described as veterinary biologicals. For the purposes of assessing and controlling risks, these fall into two groups: crude products (e.g. serum and other blood products) and medicinal products (e.g. vaccines and other immunological products). This second group is covered by another paper in this issue of the Review. Risk reduction methods may be applied to crude veterinary biologicals pre- or post-importation. Pre-importation methods include product treatment, or ensuring that the source of the product is "risk-free'. Post-importation risk reduction involves product testing, or treatment achieved by channelling products to commercial operations which are covered by European medicines legislation. At present, EU Member States issue health certificates individually for crude veterinary biologicals, and conditions for entry may differ between States. This process will soon be harmonised (the provisions for marketing medicinal products have already been harmonised).

Animal Diseases↗

PubMed1994

Relation between heart rate variability early after acute myocardial infarction and long-term mortality.

The relation between both time and frequency domain analyses of RR variability and mortality was examined in a series of 226 consecutive patients with acute myocardial infarction admitted to 3 district hospitals in London. All patients underwent 24-hour Holter monitoring early after infarction (mean 83 hours, range 48 to 180), and time and frequency domain analyses of RR variability were performed using commercially available software. During an 8-month follow-up period (range 3 to 12 months), there were 19 cardiac deaths (8.4%). Time domain analysis confirmed reduced RR variability (SDRR, SDANN, SD) among nonsurvivors compared with survivors. However, there was no difference between the groups when the percentage of absolute differences between successive RR intervals > 50 ms (pNN50) and the root-mean-square of successive differences (RMSSD)--vagal measures of RR variability--were analyzed. Frequency domain analysis demonstrated a significant difference between those who died and the survivors when the low-frequency component--modulated by both vagal and sympathetic mechanisms--was analyzed; however, this was less marked when the high-frequency component--modulated by vagal activity--was analyzed. None of these measures of RR variability was related to infarct site or left ventricular ejection fraction. In conclusion, the data confirm the association between low RR variability and mortality after acute myocardial infarction. However, the mechanism does not appear to relate exclusively to decreased parasympathetic tone. The data suggest that the increased risk of early mortality associated with reduced RR variability reflects an imbalance in sympathovagal function that is unrelated to left ventricular function.

Adult↗

PubMed1994

Mechanisms of cold intolerance in patients with angina.

OBJECTIVES: Patients with angina often report that symptoms are worse in cold weather. This study was designed to determine differences between cold-tolerant and cold-intolerant patients in the hemodynamic and ischemic response to exercise at cold temperatures and to assess the role of catecholamines and baroreceptor function. BACKGROUND: Studies have suggested that the heart rate response may differ at cold temperatures, but the mechanism and role of this variation have not been examined. METHODS: Seven cold-intolerant and seven cold-tolerant patients with angina underwent exercise treadmill testing at 6 and 25 degrees C with measurement of catecholamines. Baroreceptor function was assessed by the decrease in systolic blood pressure after patients stood up from the supine position. RESULTS: Norepinephrine levels increased by 139% in the cold environment, but there were no differences between cold-intolerant and cold-tolerant patients. Consequently, blood pressure was higher in the cold environment in all patients, but the heart rate response was similar. However, cold-intolerant patients had a steeper heart rate response in the cold and developed ischemia (mean [+/- SEM] 201 +/- 58 vs. 242 +/- 50 s, p = 0.05) and angina (348 +/- 87 vs. 449 +/- 60 s, p = 0.04) earlier in the cold environment, a difference not seen in the cold-tolerant patients. Baroreceptor function was impaired in cold-intolerant patients (decrease in systolic blood pressure after patients stood up from the supine position 19 +/- 7 vs. 0 +/- 4 mm Hg, p = 0.04). CONCLUSIONS: Exposure to cold causes an increase in blood pressure with an associated increase in myocardial oxygen demand in all patients. In cold-tolerant patients, this increase may be offset by a reduction in heart rate if baroreceptor function is normal. If baroreceptor function is abnormal, heart rate may not decrease in response to a cold-induced increase in blood pressure. This mechanism may account for some of the variability in tolerance to cold exposure that affects patients with exertional angina.

Angina Pectoris↗

PubMed1994

Reexamination of the role of endogenous opiates in silent myocardial ischemia.

OBJECTIVES: This study was designed to examine the role of beta-endorphin and met-enkephalin in the pathophysiology of silent myocardial ischemia, with emphasis on their role in the physiologic response to stress. BACKGROUND: Silent myocardial ischemia is more common in patients whose perception of pain is reduced. Whether endogenous opiates can contribute to this process remains uncertain largely because of the conflicting findings of previous studies. METHODS: Forty-three patients with coronary artery disease and ischemia on treadmill stress testing underwent electrical pain tests and exercise treadmill tests during naloxone and placebo infusion in a randomized, double-blind crossover study. Thirty-one patients developed angina during both treadmill tests (group A), and 12 had silent ischemia (group B). Plasma beta-endorphin, metenkephalin, epinephrine, norepinephrine and cortisol were measured before and after exercise in a subgroup of 17 patients. RESULTS: Naloxone reduced electrical pain tolerance (1.40 +/- 0.10 [mean +/- SEM] vs. 1.72 +/- 0.19 mA, p = 0.04) but did not affect the time to angina in group A (260 +/- 20 vs. 248 +/- 20 s, p = 0.72) or induce angina in group B patients. Beta-endorphin and met-enkephalin levels during placebo infusion were not significantly different in groups A and B at baseline and after exercise, although beta-endorphin levels were significantly increased during naloxone infusion, confirming effective opiate receptor blockade. Norepinephrine and cortisol increased with exercise, but catecholamines and cortisol were similar in both groups and were unaffected by naloxone. CONCLUSIONS: Beta-endorphin and met-enkephalin were similar in patients with painful and silent ischemia, and naloxone infusion did not influence anginal symptoms despite effective opiate receptor blockade and a reduction in somatic pain tolerance. These findings suggest that endogenous opiates do not play an important role in modulating symptoms in myocardial ischemia. The increase in beta-endorphin with exercise that coincided with an increase in plasma cortisol is most likely due to its release from the anterior pituitary gland as part of the physiologic stress response.

Double-Blind Method↗

PubMed1994

Influence of the autonomic nervous system on circadian patterns of myocardial ischaemia: comparison of stable angina with the early postinfarction period.

OBJECTIVE: To compare the circadian rhythm of myocardial ischaemia in patients with stable angina with that in patients in the early postinfarction period with particular emphasis on the role of the autonomic nervous system. PATIENTS: 44 patients with stable angina and ischaemia on treadmill testing (group A) were compared with 131 patients in the early postinfarction period (group B). All had 48 hour ambulatory Holter monitoring. SETTING: Coronary care unit and cardiology department of a district general hospital. DESIGN: Prospective, between group, comparative study. RESULTS: 337 ischaemic episodes occurred in 35 patients in group A and 370 ischaemic episodes occurred in 65 patients in group B. 34% of patients in group A had only silent episodes of ischaemia compared with 97% in group B (p < 0.0001). In group A ischaemic episodes showed a circadian rhythm that peaked during the daytime hours (p < 0.0001), but this was not seen in group B. Both the high (0.15-0.40 Hz) and low (0.04-0.15 Hz) frequency spectral components of heart rate variability showed a clear circadian rhythm (p < 0.0001); peak values occurred during the sleeping hours, although this pattern was less pronounced in group B. The ratio of low to high frequency variability (a measure of sympathovagal balance) showed a peak in daytime hours in group A (p < 0.002), but this was not seen in group B. CONCLUSION: In stable angina, myocardial ischaemia peaks during the day and is associated with a similar circadian rhythm of sympathovagal balance. In the early postinfarction period both the ischaemic and sympathovagal rhythms are severely diminished or lost altogether. Circadian changes in sympathovagal tone may explain, at least in part, the circadian rhythm of ambulatory myocardial ischaemia in patients with stable angina.

Angina Pectoris↗

PubMed1993

Silent myocardial ischemia: role of subclinical neuropathy in patients with and without diabetes.

OBJECTIVES: Silent myocardial ischemia is common in patients with diabetes. This study was designed to assess the role of subclinical autonomic impairment in diabetic patients with silent ischemia. BACKGROUND: Studies have suggested that silent ischemia is more common in diabetic patients with microvascular complications, but this has not been a consistent finding. METHODS: Twenty-two diabetic and 30 nondiabetic patients with proved coronary artery disease and a history of angina and ischemia on treadmill stress testing underwent clinical tests of autonomic function and measurement of 24-h heart rate variability. Diabetic patients with a history of microvascular complications were excluded. RESULTS: Although all 52 patients manifested ischemia during treadmill testing, only 36 patients experienced angina (angina group), whereas 16 did not (silent ischemia group). Diabetic and nondiabetic patients were similar in age (59 +/- 1 vs. 61 +/- 2 years, p = 0.56) and extent of coronary artery disease. However, clinical tests showed reduced parasympathetic function in the diabetic patients (Valsalva ratio 1.38 +/- 0.07 vs. 1.60 +/- 0.06; p = 0.007). Patients in the silent ischemia group were more often diabetic (33% vs. 63%, p = 0.05) and had prolonged time to ischemia on treadmill testing (200 +/- 20 vs. 271 +/- 20 s, p = 0.03). In addition, autonomic function was impaired in the silent group (supine/standing heart rate ratio 1.15 +/- 0.02 vs. 1.05 +/- 0.02, p = 0.002). Subgroup analysis showed that abnormalities of autonomic function were confined to the diabetic patients in the silent group. CONCLUSIONS: Despite the absence of overt microvascular complications, diabetic patients with silent exertional ischemia have evidence of significant autonomic impairment compared with findings in symptomatic patients. This difference is not seen in nondiabetic patients and indicates that subclinical neuropathy is an important cause of silent ischemia in patients with diabetes.

Adult↗

PubMed1993

Circadian and seasonal factors in the pathogenesis of acute myocardial infarction: the influence of environmental temperature.

OBJECTIVE: To determine the circadian and seasonal variations in the incidence of acute myocardial infarction and the influence of environmental temperature. PATIENTS: 633 consecutive patients with acute myocardial infarction admitted to a coronary care unit over four years. SETTING: Coronary care unit in a district general hospital. DESIGN: An observational study. RESULTS: The onset of acute myocardial infarction had a circadian rhythm with a peak in the second quarter of the day. A seasonal variation was also found with a significant winter peak. There was, however, an excess of infarctions on colder days in both winter and summer indicating that the effect of environmental temperature on the onset of acute myocardial infarction is independent of the time of year. CONCLUSION: Acute myocardial infarction is more common in winter and more common on colder days, independent of season. Environmental temperature may play an important part in the pathogenesis of acute myocardial infarction.

Adult↗

PubMed1993

Assessment of Holter ST monitoring for risk stratification in patients with acute myocardial infarction treated by thrombolysis.

OBJECTIVES: To evaluate the role of Holter ST monitoring for identifying patients at risk of recurrent ischaemic events after acute myocardial infarction treated by thrombolysis. BACKGROUND: The natural history of myocardial infarction has changed with the introduction of thrombolytic treatment. There is now a lower mortality but a higher incidence of recurrent thrombotic events (reinfarction, unstable angina). Preliminary evidence indicates that Holter ST monitoring may be of prognostic value in patients with acute myocardial infarction, but there are limited data available in patients treated by thrombolysis. METHODS: Prospective observational study of 256 consecutive patients who presented with acute myocardial infarction treated by thrombolysis. All underwent 48 hour Holter ST monitoring early after thrombolysis (mean 83, range 48-180 hours) and were followed up for eight (range three to 12) months. RESULTS: Recurrent ischaemic events occurred in 45 patients (fatal reinfarction 17, non-fatal reinfarction 12, unstable angina 16). Also four patients died as a result of progressive heart failure, and a further 15 patients required revascularisation. Analysis of the Holter data showed that 32% of patients had at least one episode of isolated ST depression (> or = 0.1 mV) and 41% either ST depression or elevation (> or = 0.2 mV). Ischaemic episodes were silent in 95% of cases. Event free survival analysis showed a significant association between Holter findings and recurrent ischaemic events (ST depression: p = 0.009; ST depression or elevation: p = 0.002). The association remained significant when the end point was restricted to fatal or non-fatal reinfarction (ST depression: p = 0.005; ST depression or elevation p = 0.001), the period of greatest risk for patients with an abnormal recording occurred early after investigation. An abnormal Holter recording identified patients at risk of early (within 30 days) reinfarction with 79% sensitivity and 60% specificity. Although positive predictive accuracy was low (11%), a normal Holter recording was associated with 98% negative predictive accuracy. CONCLUSIONS: In patients treated by thrombolysis, ST change on Holter monitoring may be useful for identifying patients at increased risk of recurrent ischaemic events, and in particular early reinfarction.

Adult↗