The ESH-ESC Guidelines published in 2007 stated that “Further emphasis has been given to identification of target organ damage, since hypertension-related subclinical alterations in several organs indicate progression in the cardiovascular disease continuum which markedly increases the risk beyond that caused by the simple presence of risk factors” Several studies have shown that the regression of asymptomatic TOD occurring during treatment reflects the treatment-induced reduction of morbid and fatal CV events, thereby offering valuable information on whether patients are more or less effectively protected by the treatment strategies adopted. The reappraisal of the ESH of 2009 (2) and thereafter the ESH-ESC Guidelines 2013 (3), encouraged the convenience of repeating TOD assessment during the follow-up. In this assessment renal evaluation is a key issue. Renal derived parameters, estimated glomerular filtration rate (eGFR) and urinary albumin and protein excretion has been considered parameters with prognostic value of risk, not only cardiovascular but also renal.
Evidence suggests that treatment-induced changes in urinary protein excretion is a marker of prognosis. In fact, a reduction in total mortality and cardiovascular mortality has been observed when a significant urinary albumin excretion reduction is achieved. Whether or not changes in microalbuminuria are of prognostic value remains controversial, although recent seems that support it. Additional advantages of renal markers as prognostic markers are availability, low cost, sensitivity to detect changes, and short time is necessary for observing the changes.
Despite the great bulk of information available demonstrating an association between regression of TOD during antihypertensive treatment and decreased mortality and cardiovascular and renal morbidity, some key questions for the clinically use of TOD remain unmet. Among them, the marker or markers to be used, the most appropriate timing to repeat it and whether or not changes in one organ can be assumed to occur in the other organs. Finally, a question to consider is if some of these TOD should be targeted during the antihypertensive treatment beyond the BP reduction. The most important factors are availability, cost, sensitivity to detect changes, time necessary for observing the changes and finally the evidence for prognostic value of the changes.
Based on these considerations ESH/ESC guidelines 2013 concludes that measuring serum creatinine, urine albumin excretion and electrocardiographic left ventricular mass in patients with hypertension is a class I recommendation with an evidence level B. Recognizing the need for more evidence regarding which combination of markers to measure, at what time points, in which patients, and with which consequence, efforts should be performed to gain grounded information for a better clinical use of TOD during antihypertensive treatment.