Prognostic significance of presenting blood pressure in non–ST-segment elevation acute coronary syndrome in relation to prior history of hypertension

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Abstract

Background

Hypertension is a well-established risk factor for cardiovascular disease, whereas low systolic blood pressure (SBP) is a powerful adverse prognosticator in acute coronary syndrome. However, it is unclear whether the prognostic significance of low SBP differs in patients with versus without prior history of hypertension. We sought to investigate the relationships between presenting SBP, prior hypertension, antihypertensive medication use, and outcomes in non–ST-segment elevation acute coronary syndrome (NSTEACS).

Methods

Using data from GRACE/GRACE2 and CANRACE, we stratified 10,337 patients with NSTEACS from 1999 to 2008 into 2 groups: those with and those without prior diagnosis of hypertension. We performed multivariable logistic regression analysis to assess the prognostic significance of prior hypertension on in-hospital mortality and tested for the interactions between prior hypertension, antihypertensive medication use, and presenting SBP.

Results

Compared with patients without prior hypertension (n = 3,732), those with prior hypertension (n = 6,605) were older; more likely to be female; and more frequently had diabetes, previous myocardial infarction, heart failure, renal insufficiency, and higher Killip class and GRACE risk scores on presentation. Patients with prior hypertension were more likely to be on antihypertensive medications before admission, to present with higher SBP, and to have heart failure or cardiogenic shock in hospital (6.0% vs 10.1%; P < .001). In-hospital mortality was higher among patients presenting with lower SBP but did not differ between the groups with and without prior hypertension. In multivariable analysis, neither prior hypertension (adjusted odds ratio = 1.15, 95% CI 0.78-1.70, P = .48) nor the number of antihypertensive medications used (P for trend = .84) was independently associated with in-hospital mortality. In contrast, SBP was a strong independent predictor of in-hospital mortality (adjusted odds ratio = 1.21 per 10 mm Hg lower, 1.15-1.27, P < .001). There was no significant interaction between SBP and prior hypertension (P for interaction = .62) or pre-admission antihypertensive medication use (P for interaction = .46) with respect to in-hospital mortality.

Conclusion

Low SBP on presentation, but not prior hypertension, was independently associated with in-hospital mortality in NSTEACS. The powerful prognostic value of SBP is similar regardless of a history of hypertension or pre-admission antihypertensive medication use.

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