Publications of the Week, October 23

Early invasive strategy in NSTE-ACS: who benefits?

High-risk patients with non-ST-segment elevation acute coronary syndrome benefit from an early invasive strategy.

In this meta-analysis the authors used individual patient data or standardized tabulated data from over 5,300 patients enrolled in 8 trials of an early versus a delayed invasive coronary intervention. The early strategy ranged from an immediate intervention to an intervention within 2, 6, 12, and – in one case – 24 hours of randomization. The methodology of analysis allowed the identification of factors possibly associated with an early intervention benefit.

Analysis involving all unselected patients has not shown a clear mortality benefit, although the estimate was in favor of the early strategy (hazard ratio, [HR], 0.81; 95% CI, 0.64-1.03).

On the other hand, patients with high-risk factors seemed to derive benefit from the early invasive strategy. This included patients with elevated troponin at baseline (HR, 0.76; 95% CI, 0.58-1.00), those with diabetes (HR, 0.67; 95% CI, 0.45-0.99), those older than 75 years of age (HR, 0.65; 95% CI, 0.46-0.93), and those with a Global Registry of Acute Coronary Events (GRACE) score (www.gracescore.org) >140 (HR, 0.70; 95% CI, 0.52-0.95).

None of the HRs for patients without those high-risk factors was associated with a statistically significant benefit of the early invasive strategy and point estimates were close to 1 on both sides.

NIV for acute respiratory failure: ERS/ATS clinical practice guidelines. Part 1 

The goal of the new European Respiratory Society and American Thoracic Society guidelines was to provide recommendations and suggestions (conditional or weak recommendations) on the application of noninvasive ventilation (NIV) in acute respiratory failure (ARF) occurring in a variety of situations. NIV refers here to continuous positive airway pressure (CPAP) or to variable positive airway pressure (usually bilevel, with a higher pressure delivered during inspiration).

Strong recommendations are issued when most individuals would want the recommended course of action, clinicians should use them in most situations, and recommendations could serve as policy and a performance measure. With weak recommendations (suggestions), the majority of patients would want the suggested course of action but many would not, clinicians should tailor their actions to individual circumstances and patient’s preferences, and the subject of policy may be the consideration of a given intervention rather than its institution. (The concepts of strong and weak recommendations are used according to the GRADE, or Grading of Recommendations, Assessment, Development, and Evaluation, method; see our introduction to the GRADE system.)

In the setting of chronic obstructive pulmonary disease (COPD), the authors:

• Suggested that NIV is not used in the setting of COPD exacerbation with hypercapnia but without acidosis (pH >7.35).
• Recommended the use of bilevel NIV for patients with COPD exacerbation resulting in pH of 7.35 or lower (usually 7.25-7.35).
• Recommended trying bilevel NIV in patients considered to require endotracheal intubation unless there is an ongoing marked deterioration.
• In terms of practical implementation considerations, the authors indicated that there is no lower limit of pH below which a trial of NIV is inappropriate but reminded that the lower the pH, the greater the risk of treatment failure and higher the need for monitoring while being prepared for potential intubation if the situation is not improving.

In the setting of acute cardiogenic pulmonary edema, the authors:

• Reviewed the evidence indicating that NIV (both bilevel and CPAP) decreases the need for intubation, reduces hospital mortality, and does not increase the risk of myocardial infarction.
• Issued a recommendation to use either bilevel NIV or CPAP for patients in ARF due to cardiogenic pulmonary edema.
• Issued a suggestion to use NIV in such patients in a prehospital setting.

In the setting of asthma, the confidence in the available evidence was very low and the authors were not able to provide even suggestions regarding the use of NIV. They pointed out, however, the possibility of asthma–COPD overlap syndrome where a trial of bilevel NIV may be considered.

The use of NIV in other settings will be discussed in the upcoming editions of Publications of the Week.

Oxygen therapy in suspected MI

In patients with suspected acute myocardial infarction (AMI) and normal oxygenation (hemoglobin oxygen saturation >90%) supplemental oxygen delivery during the first 12 hours had no beneficial effects.

Over 6,600 patients with suspected AMI presenting to the ambulance service, emergency departments, coronary care units, or catheterization laboratories with an oxygen saturation of at least 90% were randomized to supplemental oxygen (6 L per minute for 6-12 hours) or no additional oxygen. The median time from the beginning of symptoms to randomization was about 4 hours. Myocardial infarction was confirmed in about 75% of all patients (ST-segment elevation MI in about 45%) and angina pectoris was diagnosed in additional 6% of patients.

The median troponin levels were similar in supplemental and control groups: 947 versus 983 ng/L. Hypoxia requiring supplemental oxygen use developed in 1.9% versus 7.7% of patients.

There was no difference in the rate of death in hospital (1.6% vs 1.3%), death within one year (5.0% versus 5.1%), and 1-year rate of rehospitalization with AMI (3.8% vs 3.3%); either death within a year or rehospitalization with AMI at 1 year occurred in 8.3% versus 8.0% of patients.

The authors of this study concluded that there was no evidence of supplemental oxygen benefits in the setting of AMI and oxygen saturation >90%. The accompanying editorial addresses the possibility that hyperoxia may be actually detrimental.

The use of other treatments during hospitalization was generally similar in both groups: acetylsalicylic acid was received by about 84% of patients; P2Y₁₂ receptor inhibitor, 74%; statin, 84%; angiotensin-converting enzyme inhibitor or angiotensin receptor blocker, 78%; and calcium channel blocker, 16%. Coronary angiography was performed in 85% of patients, percutaneous coronary intervention in 67%, and coronary-artery bypass grafting in 3%.