In this study, we found the combination of achieved systolic blood pressure with the presence of LVH (either by ECG or Echocardiogram) might stratify the risk of CVE among older patients with CKD. Furthermore, there appears to be a graded risk, with worse outcomes in those with a SBP ≥130 and LVH vs those with a lower SBP and those without LVH.
Higher blood pressure, greater body mass index (BMI), intravascular expansion, advancing age and male gender are associated with an abnormal left ventricular geometry. This cardiac hypertrophy ultimately leads to activation of metabolic pathways that increase extracellular matrix production leading to fibrosis. Fibrosis leads to reduced contractility with myocardial wall stiffening, systolic and diastolic dysfunction, cardiomyopathy, and congestive heart failure. Changes in cardiac remodeling might be fluid, with some patients reversing to normal geometry, especially with optimal blood pressure control [11–14].
Other principles in the treatment of LVH in CKD patients include treatment of the anemia and secondary hyperparathyroidism.
Unfortunately we did not have enough data to study LV geometry and other echocardiographic parameters in this study. Other studies have found that CV event-free survival is significantly worse in the presence of concentric LVH and eccentric LVH .
There is some evidence that a concentric pattern (vs eccentric) portends a worse cardiovascular prognosis. Others suggest that LVH by itself, regardless of the geometry is associated with worse renal and cardiovascular outcomes [16, 17].
The association of hypertension and adverse outcomes has been well demonstrated. In this study we found no difference in survival among the groups, although the number of events is fairly small and definite conclusions cannot be reached.
In the SPRINT trial, aiming for a SBP lower than 120 mm Hg, as compared with less than 140 mm Hg was associated with lower rates of heart failure events, cardiovascular deaths and total deaths .
On the other hand, retrospective studies have shown increased mortality with lower blood pressures in the elderly. Kovesdy et al found that patients with a SBP of 130 to 159 mm Hg combined with a DBP of 70 to 89 mm Hg had the lowest adjusted mortality rates, comparing to those with higher or lower BP readings .
In 21,000 patients older than 65 years with stage 3-5 CKD not yet on dialysis there was increased mortality with a baseline SBP < 120 mmHg comparing to a SBP between 131-140 mmHg. A SBP higher > 140 mmHg was associated with increased mortality only in the younger patients with CKD .
We believe the discrepancy about optimal blood pressure targets in older patients might be related to the presence of CHF, since hypotension in this setting has been associated with reduced survival [21–24].
In this study, we excluded patients with a clinical diagnosis of CHF at baseline, so our findings cannot be applied to those patients with CKD and underlying CHF.
In a recent paper we have found that a low SBP (less than 120 mmHg) was associated with worse survival in patients with CKD, nonetheless that patient population had more cardiovascular comorbidities at baseline (especially CHF). Based on our current findings we think studies evaluating the optimal BP target in older patients with CKD might need to differentiate among patients with and without heart failure and LVH .
Although this was an observational study, the follow up was extensive, given the unique geographical characteristics of this population. Most patients receive their care in one of two local clinics and are admitted to one or two hospitals which share electronic medical records. This allows for close follow up of outcomes of interest.
Among the limitations of this study we cite the retrospective design, small number of patients, lack of significant number of minorities, inability to assess for reversibility of LVH changes, use of ECG and echocardiographic criteria together, although in CKD patients LVH on electrocardiogram is associated with a higher increase in CV mortality than other traditional risk factors .