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Oxygen therapy for acute myocardial infarction: A systematic review and meta-analysis (Salika)

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Oxygen therapy for acute myocardial infarction: A systematic review and meta-analysis (Salika)

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- O2 therapy for pt with acute MI are inconclusive - some studies indicate that O2 therapy may increase O2 delivery to ischemic myocardium and therefore benefit and other studies found that O2 therapy was actually harmful
- this study was a meta-analysis with the following criteria:
1. design: randomised and quasiradomised controlled clinical trials
2. population: pt with acute MI <24 hours
3.  intervention: O2 at normal pressure, regardless of O2 flow rate
4. data: 95% confidence interval
- 5 studies were included in the meta-analysis
RESULTS
- O2 could not reduce in-hospital mortality, arrhythmia incidence or pain incidence
- O2 may increase recurrent MI - may be due to O2 promoting leukocyte chemotaxis and inflammatory processes = increase number of myocardial cell death
- European Society of Cardiology recommends pt with normal O2 saturation (O2 >90%) not receive O therapy but pt with acute MI with hypoxemia are to receive O2 therapy
- bottom line - O2 inhalation did not benefit pt with acute MI

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Altered mental status predicts mortality in cardiogenic shock–results from the CardShock study (Char)

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Altered mental status predicts mortality in cardiogenic shock–results from the CardShock study (Char)

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Background and objective:

·      Altered mental status is among the signs of hypoperfusion in cardiogenic shock, the most severe form of acute heart failure

·      The purpose of the study was to investigate the prevalence of altered mental status

·      Identify factors associating with it and to assess the prognostic significance of altered mental status in cardiogenic shock

Methods:

·      Mental status were assessed as presentation of shock in 215 adult cardiogenic shock patients in a multinational, prospective, observational study

·      Clinical picture, biochemical variables and short-term mortality were compared between patients presenting with altered and normal mental status

Results:

·       Altered mental status was detected in 147 (68%) patients, whereas 68 (32%) patients had normal mental status

·       Patients with altered mental status were older (68 vs. 64 years, p=0.04) and more likely to have an acute coronary syndrome than those with normal mental status (85% vs. 74%, p=0.04)

·       Altered mental status was associated with lower systolic blood pressure (76 vs. 80 mmHg, p=0.03) and lower arterial pH (7.27 vs. 7.35, p<0.001) as well as higher levels of blood lactate (3.4 vs. 2.3 mmol/l, p<0.001) and blood glucose (11.4 vs. 9.0 mmol/l, p=0.01)

·       Low arterial pH (adjusted odds ratio 1.6 (1.1–2.2), p=0.02) was the only factor independently associated with altered mental status

·       Ninety-day mortality was significantly higher (51% vs. 22%, p<0.001) among patients with altered mental status.

Conclusion:

·      Altered mental status is common clinical sign of systemic hypoperfusion in cardiogenic shock and is associated with poor outcome

·      It is also associated with several biochemical findings that reflect inadequate tissue perfusion, of which low arterial pH is independently associated with altered mental status

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Cardiac Biomarkers and the Diagnosis of Myocardial Infarction in Women  (Tim)

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Cardiac Biomarkers and the Diagnosis of Myocardial Infarction in Women  (Tim)

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Female Coronary Heart Disease Outcomes
-          Women with suspected acute coronary syndrome are less likely to undergo investigation or receive treatment than men, and women consistently have poorer outcomes.

-          Globally, coronary heart disease remains the major cause of death in women in both high-and low- or middle-income nations.

-          Gender differences remain in diagnosis, access to investigation and treatment and outcomes.

-          Women consistently have higher case fatality rates compared to men, and these differences exist despite adjusting for age and comorbid conditions.

Cardiac Troponin
-          Troponin is a 3-piece regulatory protein complex present in cardiac and skeletal muscle and is integral to muscle contraction.

-          Both cardiac troponin T and troponin I are derived from genes specific to the myocardium, whereas troponin C is present in both cardiac and skeletal muscles.

-          Given the high specificity of cardiac troponin T and troponin I to the myocardium, quantification of these biomarkers has now become integral to the diagnosis of myocardial infarction.

-          Over the last decade, troponin assays have become increasingly sensitive which has allowed quantification of circulating troponin in the majority of individuals in a normal healthy reference population.

-          The mechanisms through which cardiac troponin is released into the circulation in the apparent ‘healthy’ state is unclear, but may reflect cardiomyocyte apoptosis and cell turnover, hypertrophy or sub-clinical myocardial fibrosis.

Sex Specific Cardiac Troponin
-          Sex differences in cardiac troponin concentrations are not widely recognised in clinical practice and may contribute to under-diagnosis of myocardial infarction in women and discrepancies in patient care and outcomes.

-          An explanation gaining increasing attention, is under-diagnosing myocardial infarction in women by not recognising that there are important differences in the reference range and diagnostic threshold of cardiac biomarkers between men and women.

-          In acute coronary syndrome, women have lower cardiac troponin concentrations than men.

Cardiovascular Studies
-          In cardiovascular medicine large randomised control trials include a majority of men. As such, the evidence on interventions in acute myocardial infarction are limited in women with data largely derived from their male counterparts.

-          Women are less likely to be recruited as they are thought to present with less typical symptoms and are older and more likely to have comorbid conditions.

-          As such, selection bias will influence the generalisability of the findings from diagnostic accuracy studies.

Suggested Causes for Sex Differences in Cardiac Troponin Ranges

-          Changes in reproductive hormones during the menstrual cycle, pregnancy and menopause influence both vasomotor function and endogenous fibrinolysis.

-          Oestrogen induced attenuation of ventricular hypertrophy

-          Difference in release and clearance kinetics

-          Greater left ventricle mass in men

-          Age adjusted higher BP in men

-          Greater sympathetic nervous activity in men

Summary
There are three main arguments in favour of adopting sex-specific thresholds:

1st Cardiac troponin concentrations are consistently lower in women than men, across multiple populations from different ethnic backgrounds.

2nd Cardiac troponin concentrations in stable populations infer different prognostic information in men and women with stronger associations noticed in women when uniform thresholds are applied.

3rd In suspected acute coronary syndrome, sex-specific thresholds for cardiac troponin I identify women at high risk of future myocardial infarction and death.

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Pharm chp 27 - Cardiac stimulants and depressants (Jas)

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Pharm chp 27 - Cardiac stimulants and depressants (Jas)

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Clinical Skill Textbook Unit 11 (by Jianmin)

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Clinical Skill Textbook Unit 11 (by Jianmin)