Ischemic Time

Effects of morphine and P2Y inhibitor amongst patients with acute coronary syndrome: A meta-analysis of comparative studies

BACKGROUND

P2Y inhibitor and morphine are widely used in caring for patients with the acute coronary syndrome (ACS), but there are some concerns about the combination use due to interaction in metabolism. Therefore, this study aimed to examine whether using morphine with antiplatelets in patients with ACS affects the clinical outcomes based on currently available evidence.

METHODS

Three databases were searched for comparative studies on this topic by using relevant keywords of ACS and morphine. Two authors independently extracted study information, mortality, major adverse cardiac event (MACE), major bleeding, and length of hospital stay. Then, they evaluated the quality of evidence independently. Meta-analysis was planned to be conducted in random-effects model. Risk ratio (RR) was used for most outcomes except hospital stay, and Peto odds ratio (POR) was used if there were any zero cells. Pooled estimate was presented with 95% confidence interval (CI).

RESULTS

Fourteen studies (n = 73,033) met eligibility criteria, and there was non-significant difference in mortality between antiplatelet with and without morphine (RR = 1.13, 95%CI: 0.78 to 1.64). Antiplatelet therapy without morphine significantly reduced the risk of MACE (RR = 0.78, 95%CI: 0.67 to 0.89; I-square = 0%), but increased the odds of major bleeding (POR = 1.87, 95%CI: 1.04 to 3.35; I-square = 0%) as compared with the combined use of antiplatelet therapy and morphine.

CONCLUSION

In conclusion, there is no statistically significant difference in mortality in patients with ACS using morphine or not, but clinicians ought to make a trade-off between a lower risk of MACE and a higher risk of major bleeding before adding morphine to antiplatelet therapy.

Electrocardiographic Q-wave "remodeling" in reperfused ST-segment elevation myocardial infarction: validation study with CMR

OBJECTIVES

The aim of this study was to evaluate the evolution in Q-wave expression during the first 5 years after a primary, successfully reperfused ST-segment elevation myocardial infarction (MI), using cardiac magnetic resonance (CMR) for infarct location, and to depict changes in infarct size and left ventricular remodeling over time.

BACKGROUND

In the absence of QRS confounders, abnormal Q waves are usually diagnostic of myocardial necrosis. It is hypothesized that Q-wave regression after MI could be related to smaller infarct sizes. Late gadolinium enhancement accurately depicts MI of any age.

METHODS

Forty-six MI patients underwent electrocardiography and CMR at 1 week (baseline), 4 months, 1 year, and 5 years post-infarction. Conventional CMR parameters were analyzed, and infarct presence, location, and size were assessed using late gadolinium enhancement CMR. Infarct locations were anterior or nonanterior (inferior and/or lateral), using late gadolinium enhancement CMR as a reference. For each time point, patients were classified as having a diagnostic/nondiagnostic electrocardiogram (ECG) using the European Society of Cardiology/American College of Cardiology Foundation/American Heart Association/World Heart Federation consensus criteria for previous Q-wave infarct.

RESULTS

At baseline, 11 patients (23%) did not meet the criteria for Q-wave MI. Non-Q-wave infarcts were significantly smaller than Q-wave infarcts (p < 0.0001). All anterior Q-wave infarcts (n = 17) were correctly localized, whereas in 7 of 19 nonanterior Q-wave infarcts, the location or extent of the infarct was misjudged by electrocardiography. At 4-month/1-year follow-up, in 10 patients (3 anterior/7 nonanterior), the ECG became nondiagnostic. The ECG remained nondiagnostic at 5-year follow-up. A cutoff infarct size of 6.2% at 1 year yielded a sensitivity of 89% and a specificity of 74% to predict the presence or absence of Q waves.

CONCLUSIONS

The incidence of nondiagnostic ECGs for previous MI using the current European Society of Cardiology/American College of Cardiology Foundation/American Heart Association/World Heart Federation criteria is substantial and increases with time post-infarction from 23% immediately post-infarction to 44% at 5-year follow-up.

Impact of transfer time on mortality in acute coronary syndrome with ST-segment elevation treated by angioplasty

BACKGROUND

In primary percutaneous coronary intervention (pPCI), conflicting data exist on the relative importance of patient presentation time (time from symptom onset (SO) to first medical contact [FMC]) and transfer time (time from FMC to sheath insertion).

OBJECTIVES

To evaluate the impact of transfer time on mortality in an unselected ST-elevation myocardial infarction (STEMI) population treated with pPCI.

METHODS

In a well-organized urban network, using mobile intensive care units (MICU) whenever possible, the impact of transfer time on inhospital mortality was evaluated in 703 unselected consecutive STEMI patients transferred for pPCI.

RESULTS

Our STEMI population included patients with cardiogenic shock (5.3%) and out-of-hospital cardiac arrest (3.7%). Longer transfer times were found to be associated with a stepwise increase in mortality ranging from 2.99% in the first quartile (Q1) up to 8.65% in the fourth quartile (Q4) (P=0.005). This result was noted in patients presenting early (≤2h of SO, 0.96% for Q1 vs. 9.8% for Q4, P=0.006) but not in late presenters (>2h of SO, 7.00% for Q1 vs. 7.8% for Q4, P=0.85). After adjustment for confounding variables such as the severity of patients, the relationship between mortality and transfer time was no longer apparent.

CONCLUSIONS

In a well-organized urban network dedicated to pPCI, including unselected STEMI patients, transfer time does not appear to be a major contributor to mortality. The relationship of transfer time to mortality seems to be dependent on presentation time and patients' clinical severity.

Improving the safety of oxygen therapy in the treatment of acute myocardial infarctions

AIM

The article examines the evidence for giving oxygen routinely to patients with suspected myocardial infarction, and addresses the challenges in changing practice.

BACKGROUND

It has been thought that administering oxygen to patients suffering from acute myocardial infarctions may be beneficial, but there is a lack of supporting evidence. Furthermore there is evidence that the use of oxygen in some circumstances may not improve clinical outcome. Despite conflicting evidence, guidelines in the past have recommended supplementary oxygen as part of treatment. Therefore it was necessary to understand and identify best practice.

METHODS

Evidence was collated using electronic databases. Search terms included 'acute myocardial infarction' 'acute coronary syndrome' 'oxygen' and 'hypoxia', 'hyperoxaemia'.

CONCLUSION

A systematic review of studies did not confirm that the use of routine oxygen in the acute stages of a myocardial infarction reduces myocardial ischemia. In reality, some evidence suggests that oxygen may even increase myocardial ischemia. Therefore it is crucial that emergency care nurses/practitioners across the world use observation skills and monitoring such as pulse oximetry to recognise the clinical need for supplementary oxygen to be given to a patient.