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Renography before heart transplantation in patients with cardiomyopathy
R M Aigner1, R E O'Mara, G F Fueger
1Department of Radiology, University Hospital, University of Rochester, Graz, Austria.
Insights
Renography can identify intrinsic renal disease in ischemic cardiomyopathy patients before heart transplantation. Abnormal kidney function detected by renography helps predict post-transplant outcomes and guides patient stratification.
Area of Science:
- Nephrology
- Cardiology
- Nuclear Medicine
Background:
- Ischemic cardiomyopathy (CM) patients awaiting heart transplantation may have abnormal renograms due to circulatory failure or intrinsic renal disease.
- Intrinsic renal disease is a contraindication for heart transplantation, necessitating accurate pre-operative assessment.
- Renography offers a non-invasive method to evaluate renal function in these patients.
Purpose of the Study:
- To analyze the differentiating and prognostic value of preoperative renograms in patients with ischemic cardiomyopathy.
- To correlate renographic findings with postoperative outcomes following heart transplantation.
Main Methods:
- Dynamic renal scintigraphy using 99mTc-mercaptoacetyltriglycine was performed on 50 patients with ischemic CM.
- Renograms were visually inspected and numerically characterized by measuring mean parenchymal transit time (mPTT), renal tracer content at 15 min (RTC15), and retention index (RI).
- Parametric renogram values were compared to a reference group, and preoperative renograms were matched with postoperative outcomes.
Main Results:
- 72% of patients (36/50) showed pathological renograms, categorized into normal, mildly delayed, and severely delayed findings.
- Distinct parametric values (mPTT, RTC15, RI) were observed for different levels of renal dysfunction.
- Postoperative serum creatinine levels correlated with renogram severity: Group A (normal) had <1.5 mg/dl, Group B (mild) had 1.5-2.5 mg/dl in 78%, and Group C (severe) had >2.5 mg/dl in 75%.
Conclusions:
- Renography effectively revealed abnormal kidney function in ischemic CM patients even without structural pathology.
- Renographic abnormalities did not solely reflect circulatory failure, indicating underlying renal issues.
- Numerical grading of renograms allowed patient stratification, predicting potential renal insufficiency post-transplant and guiding immunosuppressive therapy decisions.
Unlabelled:
In patients with ischemic cardiomyopathy (CM), abnormal renograms may result not only from circulatory failure (which should reverse after transplantation) but also from intrinsic renal disease (which contraindicates heart transplantation). Here, the outcome of heart transplantation was related to preoperative renograms, and the differentiating and prognostic value of renography was analyzed.
Methods:
The study population consisted of 50 patients with ischemic CM expecting heart transplantation. Anatomical renal pathology was excluded in all patients. Dynamic renal scintigraphy was performed with 99mTc-mercaptoacetyltriglycine. Background-subtracted renograms were inspected visually and characterized numerically. Mean parenchymal transit time (mPTT), renal tracer content at 15 min (RTC15) and retention index (RI) were determined. The parametric renogram values were related to a normal reference group of 64 patients. The preoperative renograms were matched with the postoperative outcome.
Results:
Three characteristic types of symmetrical findings in the kidneys were found: no pathological findings, mildly delayed peak and excretion phase and severely delayed peak and excretion phase. Pathological renograms were observed in 36 of 50 (72%) patients. The mean parametric renogram values in ischemic CM were as follows: Group A (normal kidney function), mPTT = 142+/-26.6 sec, RTC15 = 22.3%+/-4.6% and RI = 24.7+/-11.9; Group B (mild dysfunction), mPTT = 210+/-44.0 sec, RTC15 = 42.6%+/-10.3% and RI = 101.4+/-50.5; Group C (severe dysfunction), mPTT = 320+/-94.2 sec, RTC15 = 79.6%+/-15.9% and RI = 347.7+/-194.7; and reference patients (normal kidney function), mPTT = 137+/-31.1 sec, RTC15 = 22.8%+/-3.8% and RI = 24.6+/-7.9. Postoperative serum creatinine levels were <1.5 mg/dl in all Group A patients, between 1.5 and 2.5 mg/dl in 78% of Group B patients and >2.5 mg/dl in 75% of Group C patients.
Conclusion:
Renography revealed abnormal kidney function when structural pathology was excluded. The renographic abnormalities in ischemic CM did not reflect simply the circulatory failure. The numerical grading of renograms allowed patient stratification, suggestive of possible renal insufficiency after cardiac transplantation and immunosuppressive therapy. With further experience, renography may become a useful tool for predicting postoperative outcome in ischemic CM.