Hospital Admissions For Acute Myocardial Infarction Research Articles

Influence of climatic variables on acute myocardial infarction hospital admissions

Background Seasonal peaks in acute myocardial infarction (AMI) incidence have been widely reported. Weather has been postulated to be one of the elements at the basis of this association. The aim of our study was to determine the influence of seasonal variations and weather on AMI hospital admissions. Methods We correlated the daily number of AMI cases admitted to a western Sicily hospital over twelve years and weather conditions on a day-to-day basis. Information on temperature, humidity, wind force and direction, precipitation, sunny hours and atmospheric pressure was obtained from the local Birgi Air Force base. A total of 3918 consecutive patients were admitted with AMI over the period 1987–1998 (2822 men, 1096 women; M/F: 2,58). Results and conclusions A seasonal variation was found with a significant winter peak. The results of multivariate Poisson analysis show in both sexes a significant association as regards the incidence relative ratio between the daily number of AMI hospital admission and minimal daily temperature and maximal daily humidity. The incidence relative ratios (95% confidence intervals) were, in males, 0.95 (0.92–0.98) ( p < 0.001) as regards minimal temperature and 0.97 (0.94–0.99) ( p = 0.017) as regards maximal humidity. The corresponding values in females were respectively 0.91 (0.86–0.95) ( p < 0.001) and 0.94 (0.90–0.98) ( p = 0.009). Environmental temperature, and also humidity, may play an important role in the pathogenesis of AMI. These data may help in understanding the mechanisms whereby AMI events are triggered and in organizing better the assistance to ischemic patients throughout the year.

The effect of discontinuation of antihypertensives on the risk of acute myocardial infarction and stroke

ABSTRACTObjective: Adherence to antihypertensive drug treatment is suboptimal. The present study investigates the effect of early treatment discontinuation with antihypertensive drugs on the risk of acute myocardial infarction (AMI) or stroke in daily clinical practice.Methods: In the PHARMO Record Linkage System, which includes all records of drug dispensings and hospitalisations for ≥2 million subjects in the Netherlands, new users of antihypertensive (AHT) drugs ≥18 years of age were studied during the period 1 January 1993 – 1 October 2002 to determine the risk of AMI or stroke related to persistence with AHT. Patients were initially followed for 2 years to determine persistence with AHT, and then for a further 2 years or until the first hospital admission for AMI or stroke, death, or end of the study period. Patients using AHT for secondary prevention of cardiovascular disease were excluded from the study cohort.Results: The study cohort included 77 193 AHT users. The percentage of non-persistent patients was 55% at 2 years, with the lowest non-persistence rates for angiotensin-receptor blockers (ARBs) and ACE-inhibitors (40%) and the highest rates for β-blockers, calcium-channel blockers (CCBs) and diuretics (54–61%). Non-persistent AHT use was associated with a 15% increased risk of AMI (RR 1.15; 95% CI 1.00–1.33) and a 28% increased risk of stroke (RR 1.28; 95% CI 1.15–1.45).Conclusions: The results of this study show that in daily clinical practice early discontinuation of antihypertensive drug treatment in primary prevention increases the risk of subsequent AMI or stroke.

Reduced Admissions for Acute Myocardial Infarction Associated with a Public Smoking Ban: Matched Controlled Study

There has been no research linking implementation of a public smoking ban and reduced incidence of acute myocardial infarction (AMI) among nonsmoking patients. An ex post facto matched control group study was conducted to determine whether there was a change in hospital admissions for AMI among nonsmoking patients after a public smoking ban was implemented in Monroe County compared with Delaware County, Indiana without such a ban. Poisson analysis was conducted for 44 months of hospital admissions. A significant drop occurred in the number of admissions among nonsmoking patients in Monroe County after the ban whereas a nonsignificant decrease in the number of admissions occurred in Delaware County. The changes in the number of smoking-patient admissions before and after the ban were not significant.

How many people have had a myocardial infarction? Prevalence estimated using historical hospital data

BackgroundHealth administrative data are increasingly used to examine disease occurrence. However, health administrative data are typically available for a limited number of years – posing challenges for estimating disease prevalence and incidence. The objective of this study is to estimate the prevalence of people previously hospitalized with an acute myocardial infarction (AMI) using 17 years of hospital data and to create a registry of people with myocardial infarction.MethodsMyocardial infarction prevalence in Ontario 2004 was estimated using four methods: 1) observed hospital admissions from 1988 to 2004; 2) observed (1988 to 2004) and extrapolated unobserved events (prior to 1988) using a "back tracing" method using Poisson models; 3) DisMod incidence-prevalence-mortality model; 4) self-reported heart disease from the population-based Canadian Community Health Survey (CCHS) in 2000/2001. Individual respondents of the CCHS were individually linked to hospital discharge records to examine the agreement between self-report and hospital AMI admission.Results170,061 Ontario residents who were alive on March 31, 2004, and over age 20 years survived an AMI hospital admission between 1988 to 2004 (cumulative incidence 1.8%). This estimate increased to 2.03% (95% CI 2.01 to 2.05) after adding extrapolated cases that likely occurred before 1988. The estimated prevalence appeared stable with 5 to 10 years of historic hospital data. All 17 years of data were needed to create a reasonably complete registry (90% of estimated prevalent cases). The estimated prevalence using both DisMod and self-reported "heart attack" was higher (2.5% and 2.7% respectively). There was poor agreement between self-reported "heart attack" and the likelihood of having an observed AMI admission (sensitivity = 63.5%, positive predictive value = 54.3%).ConclusionEstimating myocardial infarction prevalence using a limited number of years of hospital data is feasible, and validity increases when unobserved events are added to observed events. The "back tracing" method is simple, reliable, and produces a myocardial infarction registry with high estimated "completeness" for jurisdictions with linked hospital data.

Missed Opportunities in the Primary Care Management of Early Acute Ischemic Heart Disease

The role of primary care clinicians (physicians, nurse practitioners, and physician assistants) in evaluating acute cardiac ischemia is not well documented in office-based settings. Decision aids developed in the emergency department and other settings may help identify missed opportunities to intervene in symptomatic outpatients before hospitalization for acute myocardial infarction. We conducted a case-control study of patients with no history of heart disease in a multisite group practice. Cases ("missed opportunities") were outpatients evaluated by primary care clinicians for chest pain or other anginal equivalents within 30 days of hospitalization for acute myocardial infarction and not referred for immediate hospital care (n = 106). We identified 3 control patients matched to each case (n = 318) using initial symptom and encounter date. We assessed the ability of several coronary risk prediction tools to identify missed opportunities. We identified 966 acute myocardial infarction hospital admissions among nearly 250,000 adults, including 261 (27.0%) with qualifying office visits in the preceding 30 days and 106 (11.0%) who were not directly referred for hospital care (cases). Chest pain (50.0%) and dyspnea (26.4%) were present in most of these cases. A Framingham risk score of 10% or greater was associated with missed opportunities (odds ratio, 19.5; 95% confidence interval, 9.3-40.6). Increased scores using the Diamond and Forrester probability and the Goldman prediction tool were also associated with missed opportunities. Primary care clinicians play an important role in the management of acute cardiac ischemia. The Framingham risk score can help identify missed opportunities that warrant more intensive evaluation.

Adherence to evidence-based statin guidelines reduces the risk of hospitalizations for acute myocardial infarction by 40%: a cohort study

To investigate the 'real world' effectiveness of robust statin therapy, focusing on the effect of dose and early treatment discontinuation on the risk of hospitalization for acute myocardial infarction (AMI). In the PHARMO database, including among others drug-dispensing and hospital discharge records for more than two million subjects in the Netherlands, 59,094 new users of statins in the period 1 January 1991 until 31 December 2004, >or=18 years of age were identified. In these patients, exposure to statins, both in terms of persistence and dose, was determined over the first two treatment years. To determine the risk for AMI, patients were followed from this 2-year time point until the first hospital admission for AMI, death, or end of the study period. A total of 31,557 patients (53%) discontinued statin use within 2 years; 20 883 patients (35%) were persistent users with an average equipotent dose>or=4. A 30% reduction in risk of hospitalization for AMI with persistent statin use was observed. The protective effect increased with a higher dose (20 and 40% risk reduction with an equipotent dose<or=3 and >or=4, respectively). These results show that statins are suboptimally used in real life for having the maximum benefit in terms of preventing AMI.

Relation of Atmospheric Pressure Changes and the Occurrences of Acute Myocardial Infarction and Stroke

Previous studies have demonstrated variation in vascular events with respect to season and time of day. Changes in barometric pressure display daily and seasonal variations and could modulate the occurrence of vascular events. The objective of this study was to determine whether a relation exists between changes in barometric pressure and occurrence of stroke or acute myocardial infarction (AMI). A retrospective analysis of hospital admissions for AMI and stroke from 1993 to 1996 in central Texas was related to changes in atmospheric pressure that were obtained from the National Climatic Data Center. Patients who had AMI (n = 1,327) or stroke (n = 839) were identified from a computerized hospital database. Mean atmospheric pressure, greatest change in pressure, and rate of change in pressure per 24-hour period were computed. One-, 2-, and 3-day and seasonal groupings of cardiovascular events were related to corresponding changes in barometric pressure. The fall and winter seasons had the highest variability in atmospheric pressure readings. There was a significant correlation (p = 0.0083) between a decrease in atmospheric pressure and the occurrence of AMI the day after a pressure decrease, especially during the fall and winter seasons. No relation between stroke and atmospheric pressure was demonstrated. In conclusion, we conclude that rapid decreases in barometric pressure are associated with the occurrence of AMI but not of stroke.

Markedly Changed Age Distribution among Patients Hospitalized for Acute Myocardial Infarction

Objective : To investigate trends in number of hospital admissions due to acute myocardial infarction (AMI) in different age groups during the last decade. Design : Data on all AMI hospital admissions since 1991 were analysed by gender and by age applying 5-year age groups between ages 60 and 90, and < 60 and S 90 as separate groups. Results : From 1991 to 2000 the number of hospital admissions for AMI was reduced by 18%. In men, AMI rates decreased in all age groups below 80 years and increased in older ages, while in women the corresponding breaking point between decreased and increased rates was 85 years. In the age group < 80 years, men and women included, the number of AMI admissions decreased by 29% (from 11 540 to 8233), while for those S 80 there was an increase of 25% (from 2917 to 3659). Over the decade the ratio of the numbers of AMIs in ages above and below 80 years increased from 0.25 to 0.44. Conclusion : Over the last decade a striking change in age distribution among AMI patients took place, with a marked decrease in age groups below 80 years, as opposed to an equally strong increase in the oldest age groups. The development with regard to trends for AMI morbidity in society has been more favourable than what appears from overall numbers of AMIs.

Evolutionary pattern and prognostic importance of heart rate variability during the early phase of acute myocardial infarction

Aims: To investigate the evolution of time domain heart rate variability in the early phase of acute myocardial infarction (MI) and assess its prognostic ability. Methods: We analysed several measures of heart rate variability (SDNN, SDANN, SDNN index, RMSSD) in 138 patients at days 0, 1 and 5±1 after hospital admission for acute MI. Results were correlated with infarct site, clinical variation and clinical outcome (death, MI, PTCA, CABG surgery). Results: Measures of heart rate variability (SDNN, SDANN and SDNN index) declined during the first 24 h after acute MI ( P<0.01) and increased to admission levels after about 5 days. SDNN values on day 0, 1 and 5 respectively were: 86±35, 75±28 and 87±27 ms. Patients with anterior infarction had lower heart rate variability than patients with inferior infarction on all test days but similar evolution patterns. After 3 years of follow-up there were 12 cardiac deaths (8.7%) and six resuscitated arrests and 33 (24%) new MIs, or revascularisation procedures. The evolutionary pattern of heart rate variability was similar in survivors to those who died although values were generally lower. Mortality was significantly higher in the group with SDNN<50 ms at day 1 ( P<0.01) and 5 ( P<0.05), but not at day 0. Conclusions: Our findings show that autonomic imbalance, already evident on the day of the acute event, progresses further over the next 24 h and recovers over the next few days. Low heart rate variability as early as 24 h after acute MI may be a useful predictor of cardiac mortality and contribute to the early risk stratification and therapeutic management of patients.

Acute myocardial infarction admissions to hospital and the socioeconomic environment in Nottingham Health District, UK

It is well established that socioeconomic environmental factors affect our health, and, because development of coronary heart disease may be influenced markedly by social and material disadvantage, indices of areal socioeconomic status were developed from the last three Census returns, and combined with disease data to analyse socioeconomic differentials in trends and incidence of acute myocardial infarction in Nottingham Health District since 1973. Data were retrieved from the Nottingham Heart Attack Register to identify patients who had sustained an AMI and were admitted to hospital. Utilizing geocoding and georeferencing procedures the postcode of every individual was identified and used to locate each geographically within a geographical information system. Acute myocardial infarction hospital admission rates fluctuated during two decades of study but were generally lower in more advantaged areas. Specific geographical areas were highlighted as having higher or lower than expected numbers of acute myocardial infarction admissions and a strong association with type of socioeconomic environment was evident. The socioeconomic differentials identified suggest that efforts aimed at reducing coronary heart disease could be improved by targeting specific socioeconomic environments. This technique will direct health promotion and cardiac resources to those areas and populations with the greatest need.

Cost–effectiveness of vitamin E therapy in the treatment of patients with angiographically proven coronary narrowing (CHAOS trial)

Epidemiologic studies have suggested that vitamin E (α-tocopherol) may play a preventive role in reducing the incidence of atherosclerosis. The aim of this paper was to conduct a cost-effectiveness analysis of vitamin E supplementation in patients with coronary artery disease using data from the Cambridge Heart Antioxidant Study (CHAOS). The study compared cost-effectiveness in the context of Australian and United States (US) health care utilization. The main clinical outcome used in the economic evaluation was the incidence of acute myocardial infarction (AMI) which was nonfatal. Utilization of health care resources was estimated by conducting a survey of Australian clinicians and published Australian and US cost data. Cost savings of $127 (A$181) and $578/patient randomized to vitamin E therapy compared with patients receiving placebo were found for Australian and US settings, respectively. Savings in the vitamin E group were due primarily to reduction in hospital admissions for AMI. This occurred because the vitamin E group had a 4.4% lower absolute risk of AMI than did the placebo group. Less than 10% of health care costs in the Australian evaluation was due to vitamin E ($150 [A$214/patient]). Our economic evaluation indicates that vitamin E therapy in patients with angiographically proven atherosclerosis is cost-effective in the Australian and US settings.