Cardio Quiz: Cardiorenal Syndromes are Not Created Equal

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Cardiorenal syndrome is subdivided based on etiology into subtypes 1-5.¹ For the cardiologist, there is much more to this disproportionate story. Chronic kidney disease (CKD) affects 30 million people in the United States.² In a cohort of approximately 2500 patients with combined heart and kidney failure, 26.2% had cardiorenal syndrome type 4 (chronic renal disease resulting in chronic heart disease).² This is a problematic category in many ways. See how much you know about it.

1. Longstanding CKD results in (more than one option may be correct):

A. Left ventricular hypertrophy (LVH)

B. Systemic inflammation

C. Pericardial disease

D. Diffuse myocardial fibrosis

Please click here for answer, discussion, and next question.

Answer: Options A (LVH), B (systemic inflammation), and D (diffuse myocardial fibrosis) are correct.

CKD progression distorts the left ventricle.² LVH is present in 80% of persons initiated on chronic hemodialysis.² Looking at LVH from another perspective, at GFRs >60 cc/min, the incidence of LVH is 32%; at 45-59 cc/min, 48%; at 30-44 cc/min, 57%, and at <30 cc/min, 75%.² The presence of LVH in the CKD population is the single greatest predictor of sudden cardiac death.² The primary cause of death is conduction system disturbances related to underlying fibrosis.² Which raises the next quesion: Why does this disease of exaggerated LVH, fibrosis, and conduction system occur in cardiorenal syndrome type 4?

2. Which of the following statements are true and which false?

A. Endomyocardial biopsies of patients with ESRD demonstrate hypertrophic and bizarre myocytes.

B. Advanced CKD per se is associated with this diffuse myocardial fibrosis.

C. Anemia is not an important factor in the progression of CKD and cardiorenal syndrome type 4.

D.  Increased phosphate levels in CKD increase the risk of heart failure.

Please click here for answer and discussion.

Answer: Options A, B, and D are true; Option C is false.²

Anemia predicts a 2-fold increase in the risk of death in CKD.² The term “cardiorenal anemia syndrome” is being proposed to describe this important risk factor.² Serum phosphate levels >6.8 mg/dl increase the odds of heart failure by 34%.²

The upcoming generation of cardiologists is going to be intimately involved with a population of patients with CKD who have a unique progression of LVH and heart failure as a result of disturbance in multiple pathways related to declining GFR. Although cardiologists can manage heart failure, the unique drivers of fibrosis-anemia of chronic renal disease and phosphate levels-will require close work between cardiology and nephrology. 

The CKD population with heart failure will not be easily managed by one subspecialty in isolation.   

References:

1. Ronco C, Bellasi A, Di Lullo L. Cardiorenal syndrome: an overview. Adv Chronic Kidney Dis. 2018; 25:382-390.

2. Edmonston D, Morris JD, Middleton JP. Working toward an improved understanding of chronic cardiorenal syndrome type 4. Adv. Chronic Kidney Dis. 2018;25:454-467.