Background: Attenuated heart rate recovery (HRR) is an independent predictor of cardiac and total mortality. Diminished renal function is a similar predictor. There are no data concerning the interaction between the two risk factors. We studied HRR in patients with a homogeneous renal disease, IgA nephropathy.
Methods: One hundred and seven patients with biopsy-proven chronic IgA nephropathy (71 males, 36 females aged 45 +/- 11 years) performed a graded exercise treadmill stress test. HRR was measured as the heart rate difference between the peak value and the heart rate 1 min after exercise. The patients were divided into three groups based on estimated glomerular filtration rate (eGFR): CKD 1, eGFR >or= 90 ml/min (n = 46); CKD 2, eGFR 60-89 ml/min (n = 38), CKD 3-4, eGFR 15-59 ml/min (n = 23). We compared these data with 29 normal controls (aged 46 +/- 14 years).
Results: HRR values corresponded to eGFR as follows: 29.9 +/- 8.8 bpm normal controls, 27.8 +/- 9.2 bpm CKD 1, 24.5 +/- 10.5 bpm CKD 2 and 16.3 +/- 9.3 bpm CKD 3-4. The latter differed from the other groups significantly (P < 0.05). Metabolic syndrome was common in IgA nephropathy patients (27%). Metabolic syndrome patients had a HRR of 19.6 +/- 10.1 bpm, compared to 25.8 +/- 10.4 bpm in patients without metabolic syndrome (P = 0.007). Nevertheless, a multivariate regression analysis accepted only eGFR as an independent predictor of HRR.
Conclusion: eGFR predicts HRR in patients with a homogenous renal disease. Metabolic syndrome influences HRR, albeit not independently in this cohort.