Impaired renal function should be routinely assessed in patients with acute coronary syndrome (ACS) and renal function is a part of the GRACE risk score. Impaired renal function is found in about 30% of ACS patients and is associated with advanced age, less use of percutaneous coronary intervention (PCI) and, independently, with mortality. It is also clearly associated with bleeding. Worsening renal function during hospitalization is also a predictor of mortality. These associations have been confirmed in the era of routine intervention and are true both for STEMI and NSTEMI. Why is impaired renal function such a bad prognostic sign? One important reason is multiple comorbidities associated with renal dysfunction. In addition, ACS is usually more severe in these patients and their complication rates, mainly bleeding, are higher.
Patients with renal dysfunction have more extensive coronary disease, a lower rate of successful PCI and more complications, including stent thrombosis and bleeding. Coronary angiography and intervention may, of course, further impair renal function. On the other hand, coronary intervention is recommended by guidelines in patients with renal dysfunction. There are registry data suggesting that renal dysfunction no longer predicts mortality after PCI. The benefit of intervention over conservative management has also been shown in patients with renal dysfunction. However, it is crucial to adjust medications and contrast volume to minimize risk in these patients. Adequate hydration and use of radial access are important in this context. Overall, with adequate precautions, an individual approach and patient education, coronary intervention is probably still beneficial in patients with advanced renal dysfunction.
As the ACS population ages, risk increases and renal dysfunction is an additional prevalent risk in this population. This is even more true in real life than in clinical trials. Renal dysfunction increases the risk of bleeding independently of choice of treatment. To reduce this risk, the first step is to consistently assess glomerular filtration rate (GFR) in these patients. Many drugs, including statins, are underutilized in patients with renal dysfunction. On the other hand, many patients with severe renal dysfunction, including dialysis, receive drugs that have not been tested, and the dosing of which is uncertain, among such patients. Many of these patients are routinely overdosed with anti-thrombotic medications, thus contributing to their risk. The presence of renal failure does not negate the benefit of antiplatelet therapy, but the risk of bleeding is clearly increased.
Patients on dialysis have an increased risk of both thrombosis and bleeding, through multiple mechanisms. They also have an increased risk of restenosis and stent thrombosis, partially due to hyporesponsiveness to clopidogrel. Most antiplatelet agents do not have significant renal elimination, although prasugrel does have some renal excretion. Ticagrelor is found to have a greater benefit over clopidogrel as renal function deteriorated, although patients on dialysis were excluded from the trial. There are no data on the use of the new antiplatelet therapy among patients on hemodialysis. Statins should be routinely used in post ACS patients but doses should be lowered.
Session Title: Impact of kidney disease on therapy and outcome in patients with acute coronary syndromes
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