On vs Off-hour PPCI in STEMI Patients (On vs Off PPCI)

October 2, 2026 updated by: Muhammad Hatem Hassan Mohammed Maghraby, Assiut University

On- Versus Off-Hour Primary Percutaneous Coronary Intervention in ST-Elevation Myocardial Infarction Patients

ST-elevation myocardial infarction (STEMI) remains a leading cause of morbidity and mortality globally, and timely reperfusion with primary percutaneous coronary intervention (PPCI) is the gold-standard treatment1. Current guidelines recommend a door-to-balloon (DTB) time of 90 minutes or less, as the benefits of PPCI increase in direct correlation with the brevity of reperfusion time.

However, there is consistent epidemiological evidence that STEMI patients presenting during off-hours (nights, weekends, and holidays) experience delays in reperfusion and worse in-hospital outcomes compared to those presenting during regular business hours. Two competing hypotheses dominate the literature. The systems hypothesis suggests that delays in care delivery during nights and weekends-including longer catheterization laboratory activation time, reduced availability of experienced operators, and logistical constraints-are the primary drivers of worse outcomes. In support of this, some studies have found that the mortality difference between off-hours and on-hours presentations is attenuated after adjusting for DTB time (Chung et al., 2020), suggesting that system-level process measures may be actionable targets for quality improvement.

Alternatively, the intrinsic severity hypothesis suggests that nocturnal STEMI presentations represent inherently more severe infarcts-characterized by higher thrombus burden, larger myocardial infarction size, and more frequent complications such as cardiogenic shock-independent of how rapidly reperfusion is achieved. Recent studies examining circadian variation in infarct size and myocardial injury biomarkers have found evidence of larger infarcts and worse systolic function in nocturnal-onset STEMI, with long-term mortality implications.

Critically, the vast majority of evidence in this field derives from retrospective registry data, particularly from North American and Western European cohorts. Data from the Middle East and North Africa (MENA) region, where demographic and healthcare system profiles differ substantially from developed nations, are essentially absent from the literature. Furthermore, contemporary data on the prospective relationships between time-of-PPCI, operator experience, procedural quality parameters (such as myocardial blush grade and ST-segment resolution), and outcomes remain limited.

A prospective study with granular intra-procedural data collection offers the opportunity to: (1) quantify the magnitude of the off-hours effect in a Middle Eastern context; (2) decompose the DTB time into its components to identify specific system bottlenecks; (3) assess whether operator seniority and team composition confound or mediate the off-hours effect6; and (4) evaluate whether procedural quality metrics (reperfusion grade, thrombus burden, microvascular perfusion) differ between daytime and nighttime PPCI and contribute to outcome disparities independent of system factors.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Detailed Description

ST-elevation myocardial infarction (STEMI) remains a leading cause of morbidity and mortality globally, and timely reperfusion with primary percutaneous coronary intervention (PPCI) is the gold-standard treatment1. Current guidelines recommend a door-to-balloon (DTB) time of 90 minutes or less, as the benefits of PPCI increase in direct correlation with the brevity of reperfusion time.

However, there is consistent epidemiological evidence that STEMI patients presenting during off-hours (nights, weekends, and holidays) experience delays in reperfusion and worse in-hospital outcomes compared to those presenting during regular business hours. Two competing hypotheses dominate the literature. The systems hypothesis suggests that delays in care delivery during nights and weekends-including longer catheterization laboratory activation time, reduced availability of experienced operators, and logistical constraints-are the primary drivers of worse outcomes. In support of this, some studies have found that the mortality difference between off-hours and on-hours presentations is attenuated after adjusting for DTB time (Chung et al., 2020), suggesting that system-level process measures may be actionable targets for quality improvement.

Alternatively, the intrinsic severity hypothesis suggests that nocturnal STEMI presentations represent inherently more severe infarcts-characterized by higher thrombus burden, larger myocardial infarction size, and more frequent complications such as cardiogenic shock-independent of how rapidly reperfusion is achieved. Recent studies examining circadian variation in infarct size and myocardial injury biomarkers have found evidence of larger infarcts and worse systolic function in nocturnal-onset STEMI, with long-term mortality implications.

Critically, the vast majority of evidence in this field derives from retrospective registry data, particularly from North American and Western European cohorts. Data from the Middle East and North Africa (MENA) region, where demographic and healthcare system profiles differ substantially from developed nations, are essentially absent from the literature. Furthermore, contemporary data on the prospective relationships between time-of-PPCI, operator experience, procedural quality parameters (such as myocardial blush grade and ST-segment resolution), and outcomes remain limited.

A prospective study with granular intra-procedural data collection offers the opportunity to: (1) quantify the magnitude of the off-hours effect in a Middle Eastern context; (2) decompose the DTB time into its components to identify specific system bottlenecks; (3) assess whether operator seniority and team composition confound or mediate the off-hours effect6; and (4) evaluate whether procedural quality metrics (reperfusion grade, thrombus burden, microvascular perfusion) differ between daytime and nighttime PPCI and contribute to outcome disparities independent of system factors.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
450

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • Egypt
    • Asyut Governorate
      • Asyut, Asyut Governorate, Egypt, 71515
        • Assiut University Heart Hospital
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Sampling Method

Non-Probability Sample

Study Population

All Acute STEMI Patients undergoing PPCI in AUHH

Description

Inclusion Criteria:

  • Age ≥18 years
  • Acute STEMI eligible for Primary Percutaneous Coronary Intervention
  • Symptom onset ≤24 hours prior to hospital presentation

Exclusion Criteria:

  • Previous myocardial infarction with known LV dysfunction (baseline LVEF <30%).
  • Cardiogenic shock secondary to mechanical complication (acute mitral regurgitation, ventricular septal defect, free wall rupture) rather than myocardial infarction.
  • Indication for emergent coronary artery bypass grafting at presentation (e.g., left main occlusion unsuitable for PCI).
  • Intra-aortic balloon pump or mechanical circulatory support initiated prior to diagnostic angiography (devices initiated post-PPCI are not exclusions)
  • Expected survival <30 days from non-cardiac causes.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Observational Models: COHORT
  • Time Perspectives: PROSPECTIVE

Cohorts and Interventions

Group / Cohort

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
On-hour Group

Patients presenting from 8:00 AM to 8:00PM
Off-Hour Group

Patients presenting from 8:00 PM to 8:00 AM, additional analysis with further stratification of holidays and weenends added to the off-hour group.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
In-hospital 4-point MACE
Time Frame: Periprocedural

In-hospital 4-point MACE: Composite binary outcome (yes/no) incorporating any of: all-cause mortality, reinfarction, ischemic stroke, Emergent Target Vessel Revascularization (TVR). For analysis, the composite will be analyzed as a binary variable
Periprocedural

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Individual MACE Components
Time Frame: Periprocedural

Binary Outcome
Periprocedural
Door-to-Balloon Time Components
Time Frame: Periprocedural

Measured in Minutes
Periprocedural
TIMI Flow
Time Frame: Periprocedural

Measured in grades (0-3)
Periprocedural
LVEF at discharge
Time Frame: Periprocedural

In Percentage
Periprocedural

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Assiut University

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Study Chair: Hamdy Shams Eddin Mohammad Taher, MD, Assiut University
  • Study Chair: Magdy Ibrahim Aldesowky Mohamed Algowhary, MD, Assiut University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
October 15, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
June 30, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 31, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
September 11, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
October 2, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
October 6, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
October 6, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
October 2, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
October 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • On Vs Off PPCI

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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