Comparison of short- and long-term benefits of reperfusion in single-vessel inferior wall acute myocardial infarction with and without right ventricular wall infarction

Prevention of Contrast Nephropathy in Critically Ill Patients Using Acetylcysteine and Theophylline

Compared with periprocedural hydration alone, acetylcysteine with hydration significantly reduces the risk of contrast nephropathy in patients with chronic renal insufficiency by 50%. For elective contrast procedures, acetylcysteine should be given in a dose of 600 mg twice daily the day before and on the procedure day. For emergency procedures, a high dose intravenous regimen (150 mg/kg in 500 mL normal saline over 30 minutes immediately before contrast followed by 50 mg/kg in 500 mL normal saline over 4h) is effective. Given the low cost and good side-effect profile of acetylcysteine, it would seem prudent to give this drug with intravenous fluids to all critically ill patients scheduled for intravenous or intraarterial contrast procedures. Theophylline in a dose of 200 mg or 2.5 mg/kg IV 30 minutes before contrast may be an effective alternative for emergency procedures. Although its benefit compared with periprocedural hydration alone seems less well established, theophylline is a particularly attractive option for emergency procedures.

Prognostic impact of right ventricular involvement in patients with acute myocardial infarction: meta-analysis

OBJECTIVE

The objective of this study was to examine the relationship between right ventricular involvement (RVI) in acute myocardial infarction (AMI) and the increase in mortality and morbidity frequently suggested in the last two decades.

DESIGN

The authors conducted a systematic review and meta-analysis.

SETTING

This study was conducted at an academic medical center.

DATA SOURCE

The authors reviewed PubMed, BioMedCentral, and the Cochrane database and conducted a manual review of article bibliographies.

STUDY SELECTION AND DATA EXTRACTION

Using a prespecified search strategy, 22 relevant studies involving a total of 7,136 patients with AMI at baseline, of whom 1,963 had RVI (27.5%), were included in a meta-analysis using a random effects model. Pooled relative risks of the impact of RVI on patient mortality and morbidity were calculated.

MAIN RESULTS

An overall pooled relative risk mortality increase of 2.59 (95% confidence interval, 2.02-3.31) was found (Z = 7.57; p < .00001). RVI in AMI was also associated with a statistically significant increase in all secondary end points assessed, including cardiogenic shock, ventricular arrhythmias, advanced atrioventricular block, and mechanical complications.

CONCLUSIONS

Our results support the view that early recognition of RVI, namely by means of right electrocardiographic leads in acute myocardial infarction, may have prognostic value. Whether or not this recognition will permit improvement of outcomes through more aggressive percutaneous coronary intervention would need to be tested in future studies.

A meta-analysis of N-acetylcysteine in contrast-induced nephrotoxicity: unsupervised clustering to resolve heterogeneity

BACKGROUND

Meta-analyses of N-acetylcysteine (NAC) for preventing contrast-induced nephrotoxicity (CIN) have led to disparate conclusions. Here we examine and attempt to resolve the heterogeneity evident among these trials.

METHODS

Two reviewers independently extracted and graded the data. Limiting studies to randomized, controlled trials with adequate outcome data yielded 22 reports with 2746 patients.

RESULTS

Significant heterogeneity was detected among these trials (I2 = 37%; p = 0.04). Meta-regression analysis failed to identify significant sources of heterogeneity. A modified L'Abbé plot that substituted groupwise changes in serum creatinine for nephrotoxicity rates, followed by model-based, unsupervised clustering resolved trials into two distinct, significantly different (p < 0.0001) and homogeneous populations (I2 = 0 and p > 0.5, for both). Cluster 1 studies (n = 18; 2445 patients) showed no benefit (relative risk (RR) = 0.87; 95% confidence interval (CI) 0.68-1.12, p = 0.28), while cluster 2 studies (n = 4; 301 patients) indicated that NAC was highly beneficial (RR = 0.15; 95% CI 0.07-0.33, p < 0.0001). Benefit in cluster 2 was unexpectedly associated with NAC-induced decreases in creatinine from baseline (p = 0.07). Cluster 2 studies were relatively early, small and of lower quality compared with cluster 1 studies (p = 0.01 for the three factors combined). Dialysis use across all studies (five control, eight treatment; p = 0.42) did not suggest that NAC is beneficial.

CONCLUSION

This meta-analysis does not support the efficacy of NAC to prevent CIN.

N-acetylcysteine prophylaxis significantly reduces the risk of radiocontrast-induced nephropathy: comprehensive meta-analysis

The objectives of this study was to assess the overall effect of N-acetylcysteine (NAC) in preventing radiocontrast-induced nephropathy (RCIN) using all available data in the literature. RCIN is associated with increased morbidity and mortality. Existing randomized trials of NAC are small and show inconsistent results. Prior meta-analyses do not include data from the most current studies. We used standard search protocols to identify all published articles and abstracts of prospective trials using NAC with fluid hydration compared to hydration alone in patients with chronic renal insufficiency undergoing contrast procedures. A rise in serum creatinine by 0.5 mg/dl or 25% above baseline at 48-72 hr after contrast exposure was used as the primary outcome. We identified 14 trials of NAC with 1,584 patients published as full-text articles. Using a random-effects model, the use of oral NAC resulted in a significant reduction in the risk for developing RCIN (RR = 0.57; 95% CI = 0.37-0.84; P = 0.01). This finding did not significantly change in a fixed-effect model (RR = 0.55; 95% CI = 0.42-0.73) or when the data were reanalyzed using only randomized trials in all forms (i.e., articles and abstracts; RR = 0.67; 95% CI = 0.47-0.95). We identified only one important difference between the positive and the negative studies: the cumulative exposure to contrast media (174 vs. 152 ml). Metaregression did not show a significant relationship between contrast volume and the RR of developing RCIN (P > 0.10). In the trials showing benefit for NAC, the treated patients' postprocedure creatinine unexpectedly decreased by 0.21 mg/dl (95% CI = 0.33-0.08). Prophylaxis with NAC significantly reduces the risk for RCIN. The reasons for improvement in serum creatinine in patients treated with NAC are unclear, but may include improved renal blood flow due to NAC and/or vigorous hydration.