The cause–effect relationship between high blood pressure (BP) levels and increased risk of coronary artery syndrome in patients with hypertension has been clearly established . In view of the large prevalence and growing incidence of these clinical conditions in both industrialized and developing countries, great effort has been applied by International Scientific Societies and National Healthcare Systems to improve educational interventions and pharmacological strategies aimed at ameliorating BP control rates and reducing hypertension-related cardiovascular morbidity and mortality [2,3]. Despite this, observational studies report a relatively low proportion of patients achieving the recommended BP targets, particularly in the presence of concomitant clinical conditions and comorbidities [4–6].
Several reasons may explain the poor rates of BP control reported in hypertensive patients at high and very high risk. First of all, it should be noted that while it is clearly established that lowering BP levels to the recommended targets of 140/90 mmHg will produce favourable clinical outcomes in stage 1–3 hypertensive patients without comorbidities, recent large randomized controlled clinical trials have reported conflicting evidence on the beneficial effects of antihypertensive therapy in those patients with high-normal BP levels and comorbidities, mostly including acute coronary syndrome (ACS) and myocardial infarction [7,8]. In these conditions, in fact, more ‘aggressive’ antihypertensive strategies (that is BP levels below 130/80 mmHg) have often resulted in a paradoxical increase in the susceptibility to coronary events . This ‘J-curve’ phenomenon has been described for coronary artery disease, mostly myocardial infarction, but not for stroke, thus suggesting the possibility that different pathophysiological mechanisms may be involved in the homeostasis of coronary or cerebrovascular circulation . On the basis of these findings, the most recent set of European guidelines  recommended to achieve BP levels below 140/90 mmHg in this specific subgroup of hypertensive patients at a very high cardiovascular risk profile, for whom previous guidelines had recommended lower target BP.
Other relevant clinical questions, however, remain unanswered. Do we have to lower high BP during an episode of ACS? To what extent? Does the BP reductions obtained in this early stage of the disease have an impact on the short-term (in-hospital) or even long-term (out-of-the-hospital) morbidity and mortality?
Partial answers to these questions might be derived from the main findings of several large, independent, national and international, inclusive databases, made available in the past few years. These registries originate from large samples of both regulatory agencies and practicing physicians, and provide useful clinical information, particularly with regard to therapeutic targets and pharmacological options adopted in these very-high-risk populations, that may integrate the evidence from randomized clinical trials in a setting of ‘real life’ . Also, they have relatively limited economic impact, longer duration and continuous updating compared to randomized controlled clinical trials [13–15].
In this issue of the Journal of Hypertension, the main findings from the analysis of the hypertensive cohort of patients included in the Acute Myocardial Infarction in Switzerland (AMIS) Plus Registry are reported . The study was aimed at evaluating the impact of pre-existing hypertension in patients with recent ACS on short-term (in-hospital) and long-term (1-year after discharge) outcomes, and demonstrated that pre-existing hypertension had a more favourable impact on in-hospital outcome, mostly by reducing morbidity and mortality. Of note, among various factors that predicted in-hospital mortality for patients with pre-existing hypertension were lower admission systemic BP levels and no pre-treatment with statins. Also, pre-existing hypertension did not result to be an independent predictor of out-of-the-hospital mortality compared to other variables, including age, male sex and presence of comorbidities. As a final consideration, admission SBP/DBP levels in patients with and in those without pre-existing hypertension were within the high-normal values, although statistically significant differences between the two groups were recorded. Although the methodology of the study does not allow any speculation on the BP targets to be achieved in coronary artery disease patients with or without hypertension, these results seem to confirm the recommendations from current European guidelines which suggest to be cautious in aggressively lowering BP levels below 140/90 mmHg in such very-high-risk subset of patients . A longer duration of the experience reported in the study could have been much more meaningful.
In the past, we highlighted the need for more inclusive recommendations to improve the diagnostic process , to make a better use of global cardiovascular risk stratification  and to better define the BP targets to be achieved  in hypertensive patients with coronary artery disease. More recently, we reported preliminary evidence that lower SBP and SBP/DBP control was significantly related to the risk of coronary in-stent restenosis, which seems to link more strictly BP levels and progression of coronary atherosclerosis. These findings were, in fact, based on the analysis of the largest and most inclusive database on patients with coronary artery disease and coronary in-stent restenosis. This observation highlights the potential influence of BP control on the risk of coronary in-stent restenosis, and may promote the need of monitoring BP behaviour in coronary interventional procedures also in prospective studies.
Overall findings derived from large, comprehensive and updated registries, and clinical databases may provide clues to physicians for both diagnostic and therapeutic processes, especially when treating hypertensive patients following an acute myocardial infarction, and ACS with or without coronary revascularization. To date, available evidence suggests caution in extremely lowering BP levels in hypertensive patients, particularly in the presence of suspicion of underlying, asymptomatic coronary artery disease. Further studies, specifically focused on the unresolved issues of the clinical management of hypertension after ACS, are needed in the next future.
Conflicts of interest
The authors have no conflict of interest to disclose.
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