Early discharge after low-risk ST-eletavation myocardial infarction and risk of adverse clinical ouctomes. validity and applicability of the zwolle risk score in a resource-restricted health system
Authors: Al Lawati H , Nadar S K , Al Badri M , Al Ghafri M , Al Riyami A B 
Published: November 2023

Background/Introduction

A Low Zwolle Risk Score (ZRS) identifies patients suitable for early hospital discharge after primary percutaneous coronary intervention (PPCI) without subsequent increase in post-discharge major adverse events (MAE).1 Data supporting this approach in resource-limited health care systems is sparse. This is particularly relevant in locales where the primary health care infrastructure is not efficiently geared towards managing patients with cardiovascular diseases and where the risk of MAE approaches 4% in the first-year post discharge.2.

Purpose

We aim to validate the ZRS in our population and correlate it with MAE. We intend to examine the rates of the individual adverse events at 1-month and 6-months post discharge and identify any potential gaps in management during the short hospital stay.

Methods

This was a retrospective analysis from the local PCI Registry at our Hospital. It included patients from 2014-2020 who were &gt; 18 years of age who underwent PPCI for ST-elevation myocardial infarction. The rates of MAE were examined at 1-month and 6-months post-discharge. These were compared against patients with high ZRS (&gt;4) from the same registry.

Results

A total of 570 patients were included in the analysis; 406 (71.2%) had a low ZRS of &lt;4 and the remaining 164 (28.8%) were high risk (ZRS &gt;4). The low ZRS group were younger (52.8 + 11.7 yrs. vs. 64.7 + 12.4 yrs., p&lt;0.001), less likely to have CKD (6.4% vs. 17.7%, p&lt;0.001) and previous CABG (0.5% vs. 2.4%, p=0.03). The median total length of hospital stay was 2 days (IQR 1-3) and significantly shorter than that in the high ZRS group of up to 7 days (p&lt;0.001). The low-risk group were less likely to have an infarct culprit lesion in the LM (0.5% vs. 4.9%, p&lt;0.001) or the LAD (42.6% vs. 68.3%. p&lt;0.001). They were also less likely to have multivessel disease (32.8% vs. 47.6%, p=0.001). When comparing outcomes between the Low ZRS and high ZRS groups, the overall event rate at 1-month was 11.8% vs.37.1% (p&lt;0.001), respectively and 14.0% vs. 45.7% (p&lt;0.001) at 6-months, respectively. Interestingly, 1 in 20 patients at 1-month and 1 in 15 patients at 6-months post-discharge were re-hospitalized for decompensated heart failure. A ZRS of &lt;4 was associated with lower procedural (0.4% vs. 3%, p=0.01), in-hospital (2.4% vs. 14.0%, p&lt;0.001), and 6-month mortality (0.24% vs. 1.8%, p&lt;0.001). A ZRS of &gt;4 was an independent predictor of increased mortality at 6 months (OR 1.37, 95% CI 1.275-1.500, p&lt;0.001]

Conclusion(s)

Even within a resource-restricted health system, the ZRS can identify patients safe for early discharge with a low event rate at 1- and 6-months post-discharge. Additionally, a low ZRS was associated with low mortality. Our study captured more MAE than previous reports. There is a potential for optimization of medical therapy during the short hospital stay to minimize risk of adverse events, especially re-hospitalizations for heart failure.Baseline CharacteristicsMain Study Outcomes