New findings bearing on home blood pressure and cardiovascular prognosis in patients with left ventricular hypertrophy

A long research journey began 40 years ago has accumulated solid evidence on the value of left ventricular hypertrophy (LVH), assessed with echocardiographic metrics, as an independent predictor of cardiovascular events and all-cause mortality in hypertensive patients [1]. LVH is commonly regarded as a key integrated marker of subclinical organ damage, reflecting cardiac effects of hemodynamic, hormonal and metabolic factors operating in hypertension, and its predictive role, independent of conventional risk factors, including office and out-of office blood pressure (BP), has been proven for a long time. In the early 2000 s the MAssa Ventricolare sinistra nell'Ipertensione arteriosa (MAVI) study, a prospective, observational, multicenter investigation carried out in Italy on 1033 hypertensive patients aged more than 50 years followed for a period of 3 years, revealed that LVH at echocardiography doubled the risk of a composite of fatal and nonfatal cardiovascular events and all-cause death after adjustment for confounders comprising baseline BP and antihypertensive treatment [2]. Evidence has been also accumulated that new-onset LVH over time increases the risk of adverse cardiovascular outcomes. Recently, the Pressioni Monitorate e Loro Associazioni (PAMELA) study provided long-term longitudinal information on the association between increases in LV mass index (LVMI) and risk of cardiovascular mortality in 990 participants without LVH at baseline [3]. A such relationship persisted to be significant when data were adjusted for confounders, including baseline and changes in office and 24-h SBP separately or together. We therefore read with interest the report by Fujiwara et al.[4] which were able to demonstrate that participants to J-HOP (Japan Morning Surge-Home BP) Study with LVH have an increased risk of cardiovascular disease compared to their counterparts with normal LVMI and, more importantly, that likelihood of having cardiovascular events was related to the BP control defined by self-measured BP at home in the morning, but not to BP status assessed by standard office measurements. The BP control metric based on morning HBPM criteria was chosen in agreement to the findings of the same research group supporting the view that morning but not evening BP values were associated with adverse cardiovascular outcomes [5]. At first glance, the results by Fujiwara et al.[4] are in line with numerous studies that have found that out-of-office BP recordings, such as home BP monitoring (HBPM) or ambulatory BP monitoring (ABPM), are superior to office BP for predicting cardiac (and extra-cardiac) target organ damage or adverse cardiovascular events [6]. A well performed cohort study investigating the reliability and predictive value of BP measured in the office or by ABPM or HBPM on LVMI, revealed that one week of HBPM has a stronger association with LVMI than day-time, night-time or 24-h ABPM or nine office BP readings taken over three visits [7]. Possible explanations for these findings documenting that HBPM performs better than office BP and perhaps than ABPM (in line with many previous and subsequent observations) can be summarized as follows. Office BP measurements are obtained in an unfamiliar environment likely to provoke an alarm reaction. Most ABPM measurements do not reflect resting BP (with the possible exception of bed rest) and are based on a single 24-h period. HBPM, in contrast, performed in a comfort zone such as home, by collecting readings over periods of several days, can express the average of daily variability in BP. The greater predictive value of out-of-office BP has been documented in trials targeting LVH regression in the hypertensive setting. The pioneering Study on Ambulatory Monitoring of Blood Pressure and Lisinopril Evaluation (SAMPLE) by Mancia et al.[8] found that pretreatment LVMI showed no relationship with clinic SBP but a significant relationship with 24-h average SBP. Furthermore, and more importantly, the reduction in LVMI induced by a 12-month antihypertensive treatment was unrelated with the treatment-induced reduction in clinic SBP but significantly associated with the reduction in 24-h average SBP. The study by Fujiwara et al.[4] extends and offers a new piece of information on the previous evidence addressing the interplay between home BP control, LVH and cardiovascular prognosis. For this purpose, 1833 participants to J-HOP Study (mean age 65 years, 49% men) with hypertension and/or cardiovascular risk factors, in which HBPM in the morning and evening for a 14-day period as well as standard echocardiography were performed at baseline, were followed for a period of 6.8 years. Uncontrolled home BP, defined as mean morning SBP more than 135 mmHg and/or DBP more than 85 mmHg and LVH, fulfilling diagnostic sex-specific criteria recommended by ESH guidelines [9], were detected in approximately 61% in 36% of cases. A total of 140 cardiovascular events occurred during the entire period, including fatal and nonfatal stroke, fatal and nonfatal coronary heart disease and congestive heart failure. As expected, participants with LVH had a risk of cardiovascular events approximately 1.5 times higher compared to their counterparts with normal LVMI, after adjusting for major confounders. More interestingly, the separate analysis of the incidence of events in participants with LVH categorized according to home BP control showed that those with effective morning BP control, unlike the uncontrolled group, did not have an increased risk of fatal and nonfatal cardiovascular disease [adjusted hazard ratio 1.32, 95% confidence interval (95% CI) 0.70–2.50, P = 0.386]. On the contrary, LVH in participants with office BP control conferred an increased risk for total cardiovascular events. The message coming from the study by by Fujiwara et al.[4] seems to emphasize that BP control in the morning, documented by HBPM over a period of a couple of weeks, would strongly limit the risk of future cardiovascular disease and death individuals with LVH due to hypertension and associated unhealthy factors. In this regard, it is useful to point out, however, that numerous studies have revealed that there might be large differences among different populations in Europe and Asia in terms of home morning and evening BP, limiting the reliability of this specific therapeutic goal to different ethnic groups [10]. Participants with LVH and uncontrolled home BP had a greater overall burden of risk factors (obesity, diabetes, dyslipidemia), higher LVMI and left ventricular concentricity compared to their LVH counterparts with controlled home BP. Although the two groups share the presence of LVH, they are different in terms of clinical features that may have influenced the response to treatment and the evolution of organ damage. BP control is easier to acquire in patients with fewer risk factors, comorbidities and less pronounced organ damage. The lower LVMI levels observed in participants with home BP control may reflect the fact that in this setting a partial regression of LVH occurred, the favorable influence of which on cardiovascular outcomes has been widely demonstrated [11,12]. We believe that the most concrete message of this study is not that sustained home BP control sterilizes LVH-related cardiovascular risk, but rather than the evidence of uncontrolled BP prioritizes echocardiographic assessment of cardiac organ damage for more precise identification and intensive treatment of patients at very high cardiovascular risk. ACKNOWLEDGEMENTS None. The study is a review. Conflicts of interest The authors report no conflicts of interest.