Achieving door-to-balloon time ≤ 90 minutes in ST-elevation myocardial infarction: a retrospective clinical audit from a tertiary care centre in India

Abstract

Background

Timely reperfusion therapy with primary percutaneous coronary intervention (PCI) significantly improves outcomes in ST-elevation myocardial infarction (STEMI). International guidelines recommend achieving a door-to-balloon (D2B) time of ≤ 90 min in at least 90% of eligible patients. This audit aimed to evaluate institutional adherence to this benchmark at a tertiary care center in India.

Methods

A retrospective clinical audit was conducted at SRM Medical College Hospital and Research Centre over a 12-month period (January–December 2024). All adult STEMI patients presenting directly to the emergency department (ED) who underwent primary PCI were included. STEMI was diagnosed based on clinical presentation, 12-lead ECG showing ≥ 1 mm ST-segment elevation in ≥ 2 contiguous leads, and confirmed by cardiology consultation. Patients treated with thrombolysis, those with contraindications to PCI, or those transferred from peripheral facilities were excluded. Key time points ED arrival (door time defined as time of triage registration), ECG acquisition, PCI decision, and balloon inflation were recorded from electronic timestamps in the hospital information system and validated by two independent auditors. The primary outcome was the proportion achieving D2B time ≤ 90 min.

Results

Among 657 STEMI patients presenting to the ED, 620 (94.4%) underwent primary PCI. Of these, 564 patients (91.0%; 95% CI: 88.4–93.2%) achieved a D2B time within 90 min, meeting the international benchmark. The mean D2B time was 76 ± 9.4 min. Delays beyond 90 min were noted in 56 patients (9.0%), primarily due to delayed consent (37.5%), need for hemodynamic stabilization (32.1%), and diagnostic ambiguity (30.4%).

Conclusion

This audit confirmed that coordinated STEMI care at our center achieved the international D2B benchmark in 91% of eligible patients. Consent pathway optimization, enhanced triage protocols, and continuous team training are recommended to further reduce delays and improve outcomes.

Introduction

ST-elevation myocardial infarction (STEMI) is one of the most critical cardiovascular emergencies, necessitating immediate medical intervention to restore myocardial perfusion and prevent irreversible ischaemic damage. The principle of “time is muscle” underscores the urgency in treating these patients: for every minute of delay in reperfusion therapy, a significant number of myocardial cells are lost, contributing to deterioration in morbidity and increased mortality [1]. Among the available reperfusion strategies, primary percutaneous coronary intervention (PCI) is the preferred approach when it can be performed promptly by an experienced team [2, 3].

International guidelines from the American College of Cardiology (ACC), American Heart Association (AHA), and European Society of Cardiology (ESC – including the 2023 update) define the door-to-balloon (D2B) time equivalently termed door-to-device time as the interval from the patient’s arrival at the emergency department (ED) to first balloon inflation in the infarct-related artery. These guidelines recommend that this interval should not exceed 90 min in at least 90% of eligible patients [3–5]. The 2023 ESC Guidelines further reinforce that minimizing total ischemic time remains the paramount goal, acknowledging both system- and patient-level contributors to delay [5].

Achieving this benchmark requires seamless coordination among emergency physicians, nursing staff, interventional cardiologists, and cath lab personnel. In high-resource countries, systems have been optimized to meet this goal consistently. However, in low- and middle-income countries, like India, various systemic, logistical, and patient-level factors pose challenges in achieving timely PCI [6, 7]. Data from regional registries such as the CREATE Registry and the Kerala ACS Registry have highlighted significant delays in reperfusion therapy across many parts of India, driven by late presentation, absence of EMS pre-notification, triage inefficiencies, diagnostic uncertainty, financial constraints, and language barriers [8, 9].

SRM Medical College Hospital and Research Centre is a tertiary academic institution in Tamil Nadu, India, with an active primary PCI programme and a dedicated cardiac catheterization laboratory operating round-the-clock. This clinical audit was designed to evaluate institutional performance in achieving the D2B benchmark of ≤ 90 min for STEMI patients treated with primary PCI, to identify bottlenecks in the care pathway, and to propose targeted quality improvement strategies. Such audits are integral to evidence-based practice and essential for aligning clinical operations with global standards [10].

Methods

Study design and setting

This was a retrospective clinical audit conducted at SRM Medical College Hospital and Research Centre, a 1,800-bed tertiary care academic center in Kattankulathur, Tamil Nadu, India. The center performs approximately 1,200–1,400 cardiac catheterization procedures annually and accepts referrals from peripheral hospitals across the Chengalpattu district and surrounding regions. The audit period spanned January 1 to December 31, 2024. Institutional Ethics Committee approval was obtained prior to data collection (IEC Ref: IEC/2024/STEMI/001), and the requirement for individual patient consent was waived given the retrospective, audit-based nature of the study. All procedures conformed to the Declaration of Helsinki (revised 2013).

Inclusion and exclusion criteria

All adult patients (≥ 18 years) presenting directly to the ED with chest pain or chest pain equivalent were screened. Patients were included if they met all of the following criteria: (i) diagnostic 12-lead ECG showing ST-segment elevation ≥ 1 mm in ≥ 2 contiguous limb leads or ≥ 2 mm in ≥ 2 contiguous precordial leads, consistent with STEMI; (ii) confirmed diagnosis by the attending cardiologist; (iii) elevated cardiac biomarkers (troponin I or troponin T) where available; and (iv) treated with primary PCI (Fig. 1).

Fig. 1.

STEMI Care Flowchart: From Presentation to Reperfusion. This flowchart illustrates the institutional workflow for managing patients presenting with ST-elevation myocardial infarction (STEMI) in the emergency department. It outlines the critical steps from initial triage and ECG acquisition to cardiology notification, consent, and transfer to the catheterization laboratory for primary percutaneous coronary intervention (PCI). The diagram emphasizes decision-making timelines aimed at achieving a door-to-balloon (D2B) time of ≤ 90 min, in line with international guideline recommendations

Patients were excluded if they: (i) received thrombolysis as primary reperfusion therapy; (ii) had absolute contraindications to PCI; (iii) were transferred from peripheral facilities (as standardized door-time recording could not be ensured for inter-facility transfers); or (iv) experienced delays solely due to non-system factors (e.g., patient or family refusal of treatment, financial consent delays). Notably, all 620 patients who underwent primary PCI provided informed consent before the procedure; no patient underwent the procedure without consent.

Data collection and time point definitions

Data were extracted from the hospital’s electronic health records (EHR), ECG logs, triage documentation, cardiology notes, and cardiac catheterization laboratory records. All time points were derived from electronically embedded timestamps within the hospital information system to ensure objectivity and minimize recording bias. A standardized audit Proforma was used, and all entries were independently verified by two auditors; discrepancies were resolved by consensus with a senior faculty member.

Time point definitions were pre-specified as follows: (i) Door time: time of triage registration at the ED front desk, as recorded in the hospital information system; (ii) ECG time: time of completion of the first 12-lead ECG; (iii) Cath lab activation time: time of formal decision to activate the catheterization laboratory; (iv) Balloon time: time of first balloon inflation in the infarct-related artery, as recorded in the cath lab log; (v) D2B time: interval between door time and balloon time.

Statistical analysis

Descriptive statistics were used to summarize demographic and clinical data. Continuous variables are presented as mean ± standard deviation (SD); categorical variables as frequencies and percentages. The primary outcome proportion achieving D2B ≤ 90 min is reported with a 95% confidence interval (CI) calculated using the Wilson score method. Subgroup comparisons used chi-squared tests for categorical variables and independent samples t-tests for continuous variables. A two-tailed p-value < 0.05 was considered statistically significant. Missing data (< 1% for any variable) were handled by case-wise exclusion. Analyses were performed using IBM SPSS Statistics, Version 26.0.

Results

Over the 12-month audit period from January to December 2024, a total of 657 patients presented to the ED at SRM Medical College Hospital and Research Centre with a confirmed diagnosis of STEMI, as established by clinical presentation and 12-lead ECG findings. Of these, 620 patients (94.4%) were deemed suitable for primary PCI and were transferred to the cardiac catheterization laboratory for revascularization. This high proportion reflects effective early identification of STEMI cases and appropriate triage mechanisms in the ED. All 620 patients underwent the procedure after informed consent was obtained; no patient was taken to the cath lab without consent.

Among the 620 patients transferred to the cath lab, 564 patients (91.0%; 95% CI: 88.4–93.2%) successfully underwent balloon angioplasty within the recommended D2B time of 90 min or less, thus meeting the international benchmark set forth by the ACC and AHA. This result demonstrates that the institution’s STEMI care pathway achieved compliance with the recommended standard in more than nine out of every ten eligible patients. The mean D2B time for this group was approximately 76 ± 9.4 min, indicating not only successful target achievement but also relatively consistent performance with limited variation.

However, 56 patients (9.0%) experienced delays with D2B times exceeding the 90-minute threshold (Table 1). A detailed evaluation of these delayed cases revealed multiple contributing factors. The most frequently encountered cause of delay, accounting for 21 cases (37.5%), was related to delays in obtaining informed consent, either due to unavailability of a legally authorized representative, language barriers, or hesitation from family members who needed more time to understand the procedure and associated risks. In all such cases, consent was ultimately obtained before proceeding with PCI. This highlights a critical bottleneck in the transition from diagnosis to intervention, particularly in a setting where attender decisions often significantly influence timely care delivery.

Table 1.

Factors contributing to door-to-balloon time delays (> 90 min) (n = 56)

Cause of Delay / Contributing Factor	n	% of Delayed Cases
1. Delayed Informed Consent	21	37.5
Unavailability of legally authorised representative / next-of-kin at time of presentation	9	16.1
Language barrier requiring interpreter involvement	5	8.9
Family hesitancy / need for extended counselling regarding procedural risks and benefits	4	7.1
Multiple family members required for consensus decision-making	3	5.4
*All 21 patients ultimately consented and underwent PCI; no patient proceeded without consent	*21	*37.5
2. Haemodynamic Instability / Medical Stabilisation Required Prior to Transfer	18	32.1
Acute pulmonary oedema requiring non-invasive ventilation (CPAP/BiPAP) prior to transfer	6	10.7
Severe hypotension / cardiogenic shock requiring inotropic support	5	8.9
Diabetic ketoacidosis requiring correction of metabolic derangement	4	7.1
Chronic kidney disease with severe electrolyte imbalance (hyperkalaemia / acidosis) requiring stabilisation	3	5.4
Note: Current ESC/ACC-AHA guidelines recommend against deferring PCI in haemodynamically unstable patients; brief stabilisation was undertaken at the treating team’s clinical discretion in these cases
3. Diagnostic Ambiguity / Atypical Presentation	17	30.4
Non-diagnostic or evolving ECG pattern requiring serial ECGs and senior cardiology review	6	10.7
New left bundle branch block (LBBB) — STEMI equivalence required senior cardiologist confirmation	4	7.1
Atypical chest pain presentation (epigastric, jaw, arm pain only) without classic ischaemic ECG at triage	4	7.1
Suspected pericarditis / myopericarditis as ECG mimic — required echocardiography or troponin trend to differentiate	3	5.4
4. Operator- or Procedure-Related Factors	0	0.0
Coronary tortuosity / calcification identified as cause of D2B delay	0	0.0
Anatomical anomaly or access difficulty contributing to delay	0	0.0
Note: Formal operator-level analysis was not performed; absence of documented delays does not exclude operator-level contribution
TOTAL — Patients with D2B Time > 90 min	56	100.0

Abbreviations: BiPAP, bilevel positive airway pressure; CPAP, continuous positive airway pressure; CKD, chronic kidney disease; D2B, door-to-balloon; DKA, diabetic ketoacidosis; ECG, electrocardiogram; LBBB, left bundle branch block; PCI, percutaneous coronary intervention

Subcategory percentages are calculated as a proportion of all delayed cases (n = 56). Individual patients may have had more than one contributing factor; the primary identifiable cause was recorded. Patients achieving D2B ≤ 90 min (n = 564; 91.0%) are not shown

The second most common category of delay, observed in 18 patients (32.1%), was hemodynamic instability or presence of complex co-morbid conditions such as acute pulmonary edema, severe hypotension, diabetic ketoacidosis, or chronic kidney disease with electrolyte imbalance. These patients required stabilization with intravenous fluids, inotropes, non-invasive ventilation, or dialysis prior to transfer, which contributed to the procedural delay. It is acknowledged that current ESC and ACC/AHA guidelines recommend against delaying PCI in cardiogenic shock or hemodynamic instability where early reperfusion is itself the goal of stabilization; in select cases, the treating team’s clinical judgment necessitated brief pre-procedure resuscitation.

In 17 patients (30.4%), delays were attributable to diagnostic ambiguity or atypical clinical presentation. These included patients with initial non-diagnostic or evolving ECG changes, unclear chest pain symptoms, or overlapping conditions such as pericarditis or left bundle branch block. In these cases, the need for confirmatory investigations and senior cardiologist consult delayed cath lab activation.

Subgroup analysis showed no significant differences in delay rates based on gender (p = 0.43); however, patients above 65 years were slightly more represented in the delayed group, suggesting a potential link between age-related comorbidities and procedural timing, though this did not reach statistical significance (p = 0.07). Time-of-day analysis showed a modest increase in delay rates during night shifts (10.5%) compared to daytime hours (8.2%), likely reflecting logistical constraints and reduced staffing. Operator-related or procedure-related complications (e.g., anatomical complexity, coronary tortuosity, vessel calcification) were not identified as contributors to D2B time delays in this cohort; however, formal operator-level data were not available for systematic analysis.

Discussion

This clinical audit assessed D2B time performance in STEMI patients undergoing primary PCI at a tertiary care academic center in India. The key finding was that 91.0% of eligible patients achieved a D2B time of ≤ 90 min, meeting the benchmark endorsed by the ACC/AHA and ESC [3–5]. The mean D2B time of 76 ± 9.4 min further demonstrates consistent performance and a low degree of variability. These results compare favorably with data from national registries such as the STEMI India programme, where D2B compliance rates at high-performing centers range from 70 to 88%, and with findings from the CREATE Registry, which documented mean D2B times of 90–130 min across diverse Indian centers [8, 11]. Internationally, benchmark compliance exceeds 95% at accredited Chest Pain Centers in the USA and Europe, underscoring opportunities for further improvement at our institution [12].

Several system-level enablers likely contributed to the high compliance observed in this audit, including early ECG acquisition in triage, a dedicated STEMI care pathway with single-call cath lab activation, prioritization of STEMI cases in the catheterization laboratory queue, and a trained interdisciplinary emergency team. These factors align with quality improvement strategies described in global STEMI networks and highlight the value of protocol-driven, coordinated care [13].

The 9% of patients experiencing delays beyond 90 min represents a clinically important quality gap. Most notably, delayed informed consent accounted for over one-third of delays. In the Indian healthcare context, consent frequently involves family decision-making rather than individual patient autonomy, which can be complicated by cultural norms, financial concerns, and language barriers. Importantly, in our audit, all patients in the consent-delay group ultimately underwent PCI after consent was obtained no patient was taken to the cath lab without consent. Strategies to reduce consent-related delays include streamlined pre-authorized consent templates, multilingual patient information materials, and early family engagement by dedicated STEMI liaisons [7].

Hemodynamic instability and medically complex comorbidities (cardiogenic shock, pulmonary edema, diabetic ketoacidosis, CKD with electrolyte imbalance) contributed to 32.1% of delays. Current ACC/AHA and ESC guidelines unequivocally recommend against deferring primary PCI in hemodynamically unstable STEMI patients, including those in cardiogenic shock, as early reperfusion is the most effective intervention in these settings [4, 5]. In CKD patients, guidelines recommend proceeding with PCI with appropriate precautions minimum contrast volume, judicious hydration, avoidance of nephrotoxic agents, and post-procedure dialysis if necessary rather than delaying revascularization. Our data suggest a need to reinforce these guideline principles through structured education and simulation training for emergency physicians and cardiologists.

Diagnostic ambiguity (30.4% of delays) remains a recognized challenge in STEMI care. Atypical presentations, evolving ECG patterns, and mimics such as left bundle branch block or pericarditis demand real-time ECG interpretation expertise, point-of-care troponin testing, and prompt senior cardiologist involvement. Implementing algorithmic decision aids and 24/7 telecardiology consultation may reduce diagnostic latency [14].

Night-time delays, as observed in this audit, are consistent with findings from global registries demonstrating slower off-hour STEMI care [15]. Sustained 24/7 readiness including adequately staffed night-shift teams, mandated on-call response protocols, and scheduled simulation drills for nocturnal STEMI scenarios represents an actionable target for system improvement.

Regarding pre-hospital systems, our audit focused exclusively on in-hospital D2B time as the primary quality metric. Pre-hospital processes including EMS activation, pre-hospital ECG acquisition and transmission, and ambulance protocols are important determinants of total ischemic time and represent an area for future audit cycles. Recent evidence from Reddy et al. demonstrated that continuous quality improvement initiatives targeting pre-hospital STEMI triage significantly improved EMS-to-balloon times and achievement of the < 90-minute gold standard [16]. Extending our audit scope to include symptom-onset-to-first-medical-contact intervals and ambulance response times would provide a more comprehensive picture of the reperfusion pathway and align with such quality improvement frameworks.

An important limitation of this audit is the absence of clinical outcome data beyond D2B time. Future work should correlate D2B time with in-hospital outcomes, including 30-day mortality, major adverse cardiac events (MACE), left ventricular ejection fraction at discharge, and heart failure hospitalization rates. This is especially relevant for the 9% of patients experiencing delays, whose outcomes may be disproportionately impacted by prolonged ischemia.

Limitations

Several limitations of this audit warrant acknowledgement. First, the retrospective design introduces the possibility of incomplete or inaccurate data capture, though the use of electronic timestamps and dual-auditor verification mitigated this risk. Second, this is a single-center study from an academic tertiary care setting in Tamil Nadu; findings may not be generalizable to community hospitals or facilities without dedicated PCI programmes. Third, patients transferred from peripheral facilities were excluded, which limits insight into the overall regional STEMI network performance. Fourth, operator-level data including individual operator experience, number of procedures performed, and procedure-specific complications (coronary tortuosity, calcification, anatomical anomalies) were not systematically collected and may have influenced D2B times in select cases; future audits should incorporate operator-level analysis. Fifth, clinical outcomes beyond D2B time (mortality, MACE, LVEF at discharge) were not captured in this audit cycle. Sixth, the audit covered calendar year 2024; a follow-up audit incorporating 2025 data would enable trend analysis and evaluation of quality improvement interventions.

Conclusion

This retrospective clinical audit demonstrated that 91% of eligible STEMI patients treated with primary PCI at a tertiary care academic center in India achieved the internationally recommended D2B time of ≤ 90 min, with a mean D2B time of 76 ± 9.4 min. These results confirm effective institutional STEMI care infrastructure and align with high-performing centers nationally. Remaining delays attributable to consent processes, hemodynamic stabilization, and diagnostic uncertainty are largely modifiable through targeted system interventions, guideline-concordant clinical protocols, and continuous interprofessional training. Extending future audits to include pre-hospital intervals, operator-level analysis, and clinical outcomes will further strengthen quality improvement efforts and help optimize patient outcomes.

Abbreviations

D2B

Door-to-Balloon

STEMI

ST-elevation myocardial infarction

PCI

Percutaneous Coronary Intervention

ED

Emergency Department

ECG

Electrocardiogram

ACC

American College of Cardiology

AHA

American Heart Association

Author contributions

R.K - Collection of data, manuscript preparation, Clinical analysis; R.K; C.M.D and S.H - Title, Manuscript preparation, Draft correction, Clinical analysis; A.M.P and S.B - Title, Manuscript correction, Clinical analysis; B.K - Proof reading, Draft correction. All authors reviewed and accepted the final draft of the manuscript.

Funding

Open access funding provided by SRM Institute of Science and Technology for SRMIST – Medical & Health Sciences. The authors gratefully acknowledge the financial support by SRM Medical College Hospital and Research Centre, Faculty of Medicine and Health Sciences, SRMIST, Kattankulathur for defraying the article processing costs.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Ethical approval

This audit was approved by the Institutional Ethics Committee of SRM Medical College Hospital and Research Centre (Ref: IEC/2024/STEMI/001). Individual patient consent was waived given the retrospective, non-interventional audit design. All procedures were conducted in accordance with the Declaration of Helsinki (revised 2015).

Consent for publication

Informed consent was obtained from all the patients included in the study.

Competing interests

The authors declare no competing interests.