What is the clinical evidence from this study?

Study design: Cohort. Population: Ischemic stroke or transient ischemic attack (n=2325). Intervention: Low diastolic blood pressure (<60 mmHg) vs. Diastolic blood pressure 70-80 mmHg. Primary outcome: Cumulative composite events (nonfatal myocardial infarction, nonfatal congestive heart failure, and death) (HR 4.86, 95% CI 2.54-8.52).

What does this research mean for the field?

Low diastolic blood pressure (<60 mmHg) is associated with a significantly higher risk of composite cardiovascular events (HR 4.86) compared to 70-80 mmHg in patients with ischemic stroke or transient ischemic attack, a risk that persists even as systolic blood pressure targets are lowered. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.CHALLENGES_CONSENSUS.

May 27, 2020Open Access

Effect of Low Diastolic Blood Pressure to Cardiovascular Risk in Patients With Ischemic Stroke or Transient Ischemic Attacks Under Different Systolic Blood Pressure Levels

ZCZimo ChenCapital Medical University JMJinglin MoSun Yat-sen University JXJie XuWannan Medical College

Key Result

Low diastolic blood pressure (<60 mmHg) was associated with a significantly higher risk of composite cardiovascular events (HR 4.86) compared to 70-80 mmHg in patients with ischemic stroke or TIA.

Study Design

Type

Cohort (n=2,325)

Multicenter

Yes

Structured PICO

Does low diastolic blood pressure (<60 mmHg) increase the risk of composite cardiovascular events or stroke recurrence in patients with ischemic stroke or TIA?

Population

2,325 patients (aged 18 years or older) with ischemic stroke (IS) or transient ischemic attack (TIA) within 7 days of the index event, mean age 62.52, 67.23% male, from 61 hospitals in China.

Intervention

Low diastolic blood pressure (DBP <60 mmHg)

Comparator

Diastolic blood pressure 70-80 mmHg (reference category) or DBP ≥60 mmHg when stratified by SBP levels

Outcome

Cumulative composite events (nonfatal myocardial infarction, nonfatal congestive heart failure, and death of any cause) and recurrent stroke (ischemic or hemorrhagic) at 1 yearcomposite

Intensive systolic blood pressure control in patients with ischemic stroke or TIA may lead to harmfully low diastolic blood pressure (<60 mmHg), which is associated with a significantly increased risk of cardiovascular events.

Main Result

Effect estimate: HR 4.86 (95% CI 2.54-8.52)

Absolute Event Rate: 15.97% vs 2.73%

Limitations

Included adverse events that occurred within the period of pressure monitoring, ignoring the time sequence of monitoring and events
Included Chinese patients only, which may limit generalizability to other populations
Observational study design cannot fully eliminate residual confounding
Lacked information on cardiovascular mortality, necessitating the use of all-cause mortality instead

Abstract

Background: In the context of recently updated strategies of pressure management, there is a paucity of evidence on the effect of diastolic blood pressure (DBP) level on adverse events among stroke patients. This study aimed to examine the effect of low DBP (<60 mmHg) under different levels of systolic blood pressure (SBP) on the risk of cardiac events and stroke recurrence among patients with ischemic stroke (IS) or transient ischemic attack (TIA). Material and Methods: This study was conducted in 2325 patients with IS or TIA. DBP values were categorized into <60, 60–70, 70–80 (reference), 80–90, and ≥90 mmHg in the main sample and were further categorized as <60 mmHg and ≥60 mmHg (reference) when patients were stratified according to SBP levels (<140, <130, and <120 mmHg). The outcomes were defined as recurrent stroke and cumulative cardiac events (defined as the combination of nonfatal myocardial infarction, nonfatal congestive heart failure, and death) at 1 year. Results: During 1 year of follow-up, a total of 95 cardiac events and 138 stroke recurrences were identified. The patients with low DBP showed a significantly higher risk of cardiac events (hazard ratio HR=4.86, 95% confidence interval CI=2.54–8.52), especially the elderly patients (≥60 years); however, this result was not observed for stroke recurrence (HR=0.90, 95% CI=0.46–1.74). With the reduction of the SBP levels, the proportion of patients with low DBP increased (6.87%, 12.67%, 34.46%, respectively) and the risk for cardiac events persisted. Conclusions: Along with the new target levels of SBP suggested by updated criteria, there is a trend for DBP to be reduced to a harmfully low level, which was associated with an increased risk of cardiac events among patients with IS or TIA.

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