- In this retrospective study, researchers at Massachusetts General Hospital used the 2014 Nationwide Readmissions Database to identify and follow 237,549 U.S. adults who survived an acute myocardial infarction (AMI)
- 26% of survivors had either acute or chronic kidney failure at the time of their AMI hospitalization
- Compared to survivors without kidney disease, those with kidney failure had significantly increased odds of readmission for heart failure (HF) within six months after discharge (adjusted OR, 1.52–1.99 depending on type of kidney failure); this was true across prespecified subgroups
- Survivors with kidney failure, especially those with end-stage renal disease, were also at significantly greater risk of the composite outcome of six-month HF hospitalization or all-cause mortality during a non-HF-related admission
- AMI care should be optimized to minimize the development of acute kidney injury, and AMI survivors with acute or chronic kidney failure should be followed carefully after discharge so new-onset HF can be identified and early measures are taken to reduce readmissions and fatality
Patients who suffer acute myocardial infarction (AMI), acute kidney injury (AKI) and chronic kidney disease (CKD) are well known to confer a poorer prognosis. Heart failure (HF) also frequently complicates AMI and is typically diagnosed within the first six months after discharge.
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Now, researchers have linked AKI and CKD in AMI survivors to a substantially greater risk of hospitalization for HF and associated mortality. Srikanth Yandrapalli, MD, a clinical and research fellow in the Division of Cardiology and Interventional Cardiology at Massachusetts General Hospital, and William Frishman, MD, of Westchester Medical Center/New York Medical College, and colleagues present detailed data in The American Journal of Cardiology.
For this retrospective study, the researchers included 237,549 U.S. survivors of AMI who were discharged between January and June 2014 (62% male, mean age 67). The data source, the Nationwide Readmissions Database, was used to track the patients through the end of December 2014.
Kidney Disease Status
74% of the overall cohort had no acute or chronic kidney failure at the time of the AMI hospitalization. The other 26% had:
- AKI without underlying CKD—6% of overall sample; 44% of AKI sample
- AKI on CKD stage III to V—8% of overall sample; 56% of AKI sample
- Stable CKD stage III to V—9%
- End-stage renal disease (ESRD)—3%
The primary outcome, hospitalization for HF within six months, was noted in 5.4% of the patients with kidney failure versus 3.3% of those without (P<0.001).
The comparison held across prespecified subgroups: cardiovascular risk factors (age, sex, hypertension, diabetes, obesity, smoking, atrial fibrillation), AMI type (STEMI vs. non-STEMI), mechanical revascularization during AMI (yes/no), and HF at the time of AMI (yes/no).
In a risk-adjusted logistic regression analysis, patients with kidney failure had significantly higher odds of HF hospitalization:
- AKI without underlying CKD—adjusted OR, 1.52
- Stable CKD—1.72
- AKI on CKD—1.99
In the subgroup readmitted for HF, 4.6% of patients with kidney disease died during the hospitalization compared with 3.5% of those without kidney disease (P<0.001).
A composite outcome, HF hospitalization with six months or all-cause mortality during a non−HF-related admission, occurred in 7.3% of AMI survivors.
In the risk-adjusted analysis, patients with kidney failure were at greater odds of the composite outcome:
- AKI without underlying CKD—adjusted OR, 1.54
- Stable CKD III to V—1.66
- AKI on CKD—1.94
Opportunities to Improve Care
The fact that 56% of patients with underlying CKD stages III to V developed AKI underscores the substantial burden of kidney failure in AMI.
Studies conflict about why AKI develops around the time of AMI. The leading hypotheses point to hemodynamic instability and to kidney damage secondary to the use of iodinated contrast agents in angiography. Regardless of the reason, AMI care should be optimized to minimize the development of AKI, and this is particularly important for patients with CKD.
In addition, AMI survivors with acute or chronic kidney failure should be followed closely after discharge so new-onset HF can be identified and measures are taken to prevent its progression.
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