By Harold L. Karpman, MD, FACC, FACP

Clinical Professor of Medicine, David Geffen School of Medicine at UCLA

Dr. Karpman reports no financial relationships relevant to this field of study.

SYNOPSIS: In patients suffering from hypertension and coronary artery disease in routine clinical practice, systolic blood pressure of < 120 mmHg and diastolic blood pressure < 70 mmHg each were associated with adverse cardiovascular outcomes, including mortality, supporting the existence of a J-curve phenomenon.

SOURCE: Vidal-Petiot E, Ford I, Greenlaw N, et al. Cardiovascular event rates and mortality according to achieved systolic and diastolic blood pressure in patients with stable coronary artery disease: An international cohort study. Lancet 2016 388:2142-2152.

Lowering blood pressure (BP) in patients suffering from hypertension reduces the risk of cardiovascular events and death,1,2 but the optimum target BP remains unresolved.1-4 Some randomized trials have not shown a benefit of BP targets of < 140/90 mmHg. In fact, some published analyses have suggested that the benefits of BP lowering even may be reversed below a certain threshold,5-9 the so-called J-curve phenomenon.6 Vidal-Petiot et al studied the association between achieved BP levels and cardiovascular outcomes in a large cohort of patients presenting with stable coronary artery disease treated for hypertension in the CLARIFY study.11

The CLARIFY study was a prospective observational, longitudinal registry of patients presenting with stable coronary artery disease and included 32,703 patients receiving standard care for hypertension. The study was conducted in 45 countries, excluding the United States. All eligible patients presented with stable coronary artery disease and were receiving treatment with at least one antihypertensive drug for hypertension, defined as BP readings > 140/90 mmHg. BP in the office was measured annually in patients after a rest of five minutes in the sitting position. The primary outcomes measured were the composite of cardiovascular death, myocardial infarction, or stroke, and the measured secondary outcomes were each component of the primary endpoints and all-cause death and hospital admission for heart failure. The results of this very large observational, international cohort study revealed that elevated systolic BP and/or low diastolic BP levels were associated with an increased risk of cardiovascular events in patients suffering from coronary artery disease and hypertension. The authors observed the increased risk both over a threshold of 140/90 mmHg and under a threshold of 120/70 mmHg, resulting in a J-curve phenomenon.

COMMENTARY

The results from the CLARIFY trial are consistent with the results from previous analyses conducted in other randomized trials that studied patients with hypertension and coronary artery disease.7,12 Although the J-curve effect was robust and persisted after multiple adjustment procedures for potential confounders, the study was based on a large cohort from routine clinical practices with no predefined BP intervention, which might confound the analysis.

Of course, the strength of the study lies in the accuracy of the baseline and follow-up BP determinations. Another particular strength of the study is that it included a large international cohort of patients treated under real-life conditions, which might provide greater validity than the highly selected populations studied in numerous published randomized trials.13

The benefit of the observations is that they are in agreement with the results of other published studies, which concluded that the benefit of lowering BP to < 140 mmHg remains unquestionable, whereas the benefit of lowering BP to < 130 mmHg is uncertain.6,7

Systolic BP > 140 mmHg should be lowered to at least 130 mmHg, but lowering systolic BP to less than that value may actually cause harm. Lowering diastolic BP to 70-79 mmHg is associated with a better outcome than leaving diastolic BP at 80 mmHg, which is consistent with results from SPRINT.14 However, trial results stand as strong evidence against lowering diastolic BP to < 70 mmHg.

Clinicians should be fully aware of the fact that both systolic and diastolic BP readings should be carefully managed and, if abnormal, be brought to appropriate levels as outlined above, but not to abnormally low or high levels.

REFERENCES

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  11. Vidal-Petiot E, Ford I, Greenlaw N, et al. Cardiovascular event rates and mortality according to achieved systolic and diastolic blood pressure in patients with stable coronary artery disease: An international cohort study. Lancet 2016 388:2142-2152.
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