A comparison of ionic versus nonionic contrast medium during primary percutaneous transluminal coronary angioplasty for acute myocardial infarction (GUSTO IIb). Global Use of Strategies to Open Occluded Coronary Arteries in Acute Coronary Syndromes

Cardiac events after low osmolar ionic or isosmolar nonionic contrast media utilization in the current era of coronary angioplasty

OBJECTIVES

Our study aimed to compare the isosmolar nonionic dimer iodixanol and the low osmolar ionic agent ioxaglate in the current era of percutaneous coronary intervention (PCI), using clopidogrel, enoxaparine, direct stenting, and drug eluting stent.

BACKGROUND

Previous studies have suggested an association between thrombus-related events and type of contrast media.

METHODS

Our prospective single-center study included 498 consecutive patients who were assigned to receive either iodixanol (n = 231) or ioxaglate (n = 267). The primary endpoint was the cumulative rate of in-hospital major adverse clinical events (MACE). A secondary endpoint was the rate of angiographic or procedural complications.

RESULTS

Clinical and angiographic baseline characteristics and procedural data were similar in the 2 groups. A peak anti-Xa > 0.5 IU/ml was obtained in 97% in both groups. Glycoprotein IIb/IIIa inhibitors were used in 42% of patients. Coronary stenting was performed in 91% of patients, with direct stenting in 70%, and drug-eluting stent in 28% of patients. In-hospital MACE was more frequent in patients receiving iodixanol compared with those receiving ioxaglate (4.8% vs. 0.3%, P < 0.005). This difference was mainly related to the appearance of a large thrombus during PCI (6% with iodixanol vs. 0.3% with ioxaglate, P < 0.0001). In multivariate analysis, independent predictors of in-hospital MACE were use of iodixanol (P < 0.01), the higher number of stent used (P < 0.008), bifurcation/ostial lesion (P < 0.01), and balloon dilation before stenting (p < 0.001).

CONCLUSIONS

In our study reflecting the current era of PCI, thrombus-related events are more frequent with the isosmolar nonionic dimer iodixanol than with the low osmolar ionic agent ioxaglate.

N-acetylcysteine does not prevent contrast induced nephropathy after cardiac catheterisation with an ionic low osmolality contrast medium: a multicentre clinical trial

OBJECTIVE

To evaluate oral N-acetylcysteine in the prevention of contrast induced nephropathy (CIN) in patients at low to moderate risk undergoing cardiac catheterisation with ionic low osmolality contrast medium.

METHODS

In a multicentre double blind clinical trial 156 patients undergoing coronary angiography or percutaneous coronary intervention with serum creatinine > or = 106.08 micromol/l or creatinine clearance < 50 ml/min or diabetes mellitus were randomly assigned to receive N-acetylcysteine 600 mg orally twice daily for two days or placebo. Only low osmolality ionic contrast medium was used.

RESULTS

Sixteen patients developed CIN, defined as an increase of 44.2 micromol/l in creatinine in 48 hours: eight of 77 patients (10.4%) in the N-acetylcysteine group and eight of 79 patients (10.1%) in the placebo group (p = 1.00). The mean (SD) change in serum creatinine was similar in both groups: 7.96 (35.36) micromol/l in the N-acetylcysteine group and 6.19 (25.64) micromol/l in the placebo group (p = 0.67). No difference was observed in the change in endogenous creatinine clearance (-0.54 (10.4) ml/min v -2.52 (12.3) ml/min, N-acetylcysteine and placebo, respectively, p = 0.28).

CONCLUSION

Oral N-acetylcysteine did not prevent CIN in patients at low to moderate risk undergoing cardiac catheterisation with ionic low osmolality contrast medium.

Comparative tolerability of contrast media used for coronary interventions

Radiographic contrast media (CM) are necessary to provide x-ray absorption of the bloodstream; all other observed effects need to be regarded as adverse. Four types of CM are currently used in diagnostic and interventional cardiology: ionic high-osmolar CM (HOCM), either ionic or non-ionic low-osmolar CM (LOCM), and non-ionic iso-osmolar CM (IOCM). Focusing on the potential cardiovascular effects caused by the CM, there is a clear difference between HOCM and the LOCM or IOCM. HOCM have a poorer profile due to a higher incidence of hypotension and electrophysiological effects. To prevent contrast-induced nephropathy, HOCM should be avoided and patients should receive the minimal dose of LOCM or IOCM with intravenous hydration before and after the procedure. Clinical hyperthyroidism has been detected after CM use, but the condition appears, ultimately, to be self-limited and to occur mainly in elderly patients. When assessing the need for a CM in terms of improved patient safety, preventing serious complications should be the major factor determining the choice. CM should not be selected on the basis of minor adverse effects since these are, ultimately, of low clinical relevance. Thrombotic events, in contrast, carry a high clinical relevance and we consider that these should be the main issue governing current choice. Ionic LOCM appear to have better profile than other CM with respect to interaction with platelet function and coagulation. In relation to thrombotic events in randomised clinical studies, ionic CM have been associated, mainly, with favourable and some neutral results compared with non-ionic agents. Only one trial indicated a more pronounced antithrombotic effect of the non-ionic IOCM relative to the ionic LOCM. The antithrombotic advantages of ionic over non-ionic LOCM are, in part, balanced by a greater frequency of minor adverse effects such as nausea, vomiting or cutaneous rashes. A matter of concern is the delayed adverse effects observed with non-ionic IOCM. However, severe and life-threatening reactions are exceptional and there are probably no significant differences between IOCM and LOCM whether ionic or non-ionic. However, in patients with known allergies, non-ionic CM are to be recommended. On the basis of the available pre-clinical and clinical data, the ionic LOCM or the non-ionic IOCM are the agents to be recommended in percutaneous coronary interventions because of their antithrombotic advantages over non-ionic LOCM.

The ionic contrast medium ioxaglate interferes with thrombin-mediated feedback activation of factor V, factor VIII and platelets

Clinical observation shows that radiographic contrast media (CM) may influence thrombus formation. In the search for the underlying mechanism, we have shown that the ionic CM ioxaglate is a potent inhibitor of thrombin generation in platelet-poor and platelet-rich plasma, whereas the influence of the non-ionic contrast medium iodixanol is minimal. Ioxaglate boosts the inhibitory effect of the platelet GPIIb/IIIa antagonist abciximab and the effects of ioxaglate and heparin are additive. Ioxaglate inhibits the clotting of fibrinogen and the activation of factors V and VIII, and of platelets by thrombin. It does not inhibit hydrolysis of small chromogenic thrombin substrates, nor does it influence the heparin-catalyzed inactivation of thrombin by antithrombin. We assume therefore that ioxaglate interferes with the binding of macromolecular substrates to the anionic exosite I of thrombin. The biological correlation to the observed antithrombotic effect of ioxaglate is then to be found in the inhibition of thrombin generation via inhibition of thrombin-mediated feedback activations.

Impact of contrast agent type (ionic versus nonionic) used for coronary angiography on angiographic, electrocardiographic, and clinical outcomes following thrombolytic administration in acute myocardial infarction

The goal of this study was to examine the relationship between contrast agent type (ionic vs. nonionic) and angiographic, electrocardiographic, and clinical outcomes after thrombolytic administration. Ionic or nonionic contrast agents were selected in a nonrandomized fashion for 90-min angiography and percutaneous coronary intervention (PCI) following thrombolytic administration in the TIMI 14 trial [tissue plasminogen activator (tPA) or reteplase (rPA) vs. low-dose lytic + abciximab]. There was no relationship between contrast agent type and overall patency, rate of TIMI grade 3 flow, or corrected TIMI frame counts (CTFCs) in open culprit arteries and in post-PCI patency rates or post-PCI CTFCs. In patients treated with ionic contrast, ejection fractions at 90 min were slightly but significantly lower (56.2 +/- 16.5, n = 122, vs. 59.8 +/- 14.4, n = 322; P = 0.02), chest pain duration was longer (2.8 +/- 4.1 hr, n = 255, vs. 1.7 +/- 3.6, n = 550; P = 0.0003), and complete ST segment resolution was less frequent (41.5% vs. 50.8%; P = 0.04). While there was no difference in epicardial blood flow, ionic contrast agent use was associated with poorer ST segment resolution, longer chest pain duration, and poorer ejection fractions, perhaps as a result of microvascular dysfunction.