European Journal of Cardiovascular Medicine

ST-segment elevation myocardial infarction (STEMI) is a major cause of cardiovascular mortality in India, with higher incidence and mortality rates compared to developed countries [1]. Primary percutaneous coronary intervention (PCI) is the preferred reperfusion strategy, with door-to-balloon (D2B) time serving as a critical performance metric [2]. The ACC/AHA guidelines recommend a D2B time of ≤90 minutes to minimize myocardial damage [3]. In semi-urban regions like North Kerala, logistical challenges, including delayed patient presentation and consent processes, can prolong D2B times [4]. This study evaluates D2B times, identifies contributing factors, and proposes strategies to improve STEMI care in a tertiary ED in North Kerala.

Study Design and Setting

This prospective observational study was conducted at a 750-bed tertiary care hospital in North Kerala, India, from January 1, 2024, to December 31, 2024. The hospital, equipped with a 24/7 catheterization laboratory, serves a semi-urban population and handles approximately 50,000 ED visits annually. The study was approved by the Institutional Review Board (IRB/2023/045), with written informed consent obtained from all participants or their surrogates.

Study Population

We enrolled 300 consecutive patients aged ≥18 years presenting to the ED with acute STEMI within 12 hours of symptom onset. STEMI was confirmed by electrocardiogram (ECG) showing ST-elevation ≥1 mm in ≥2 contiguous leads or new left bundle branch block [3]. Patients scheduled for primary PCI were included. Exclusion criteria included out-of-hospital cardiac arrest, thrombolytic therapy, or transfer from another facility.

Data Collection

Data were collected via a hospital-based STEMI registry. Key time points included:

• Door-to-ECG time (ED2ECG): Time from ED arrival to ECG acquisition (goal ≤10 minutes).
• ED-to-CCU time (ED2CCU): Time from ED arrival to transfer to the coronary care unit (goal ≤20 minutes).
• Consent time: Time from PCI discussion initiation to written consent (goal ≤15 minutes).
• Post-consent-to-balloon time

(POSTCONSENT2B): Time from consent to balloon deployment (goal ≤30 minutes).

• Door-to-balloon time (D2B): Time from ED arrival to balloon deployment (goal ≤90 minutes).

Demographics, comorbidities, STEMI type, culprit vessel, total ischemic time (TIT, from symptom onset to balloon deployment), and outcomes (in-hospital mortality, TIMI flow grades, mechanical support use) were recorded. Times were documented using synchronized clocks, with data verified via electronic medical records.

Statistical Analysis

Continuous variables were reported as means ± standard deviations (SD) or medians (interquartile ranges) for non-normal data. Categorical variables were expressed as percentages. Spearman’s correlation coefficient (ρ) assessed relationships between time segments and D2B time. Multivariable logistic regression identified predictors of D2B delays (>90 minutes), adjusting for age, sex, time of presentation, and comorbidities. A p-value <0.05 was considered statistically significant. Analyses were performed using SPSS version 26 (IBM Corp, Armonk, NY).

Baseline Characteristics

Table 1 summarizes the baseline characteristics of the 300 patients. The majority were male (78%), with a mean age of 58 ± 11.2 years. Hypertension (62%) and diabetes (45%) were prevalent, and 18% had prior coronary artery disease. Anterior STEMI was diagnosed in 65% of cases, with the left anterior descending artery as the most common culprit vessel (60%). Median TIT was 180 minutes (IQR: 120–240 minutes).

Table 1: Baseline Characteristics of Study Population (N=300)

Time Metrics

The mean D2B time was 62 ± 14.5 minutes, with 92% of patients achieving D2B ≤90 minutes. Table 2 presents the time segment results.

Table 2: Time Metrics for STEMI Patients (N=300)

Figure 1 illustrates the distribution of D2B times, showing a right-skewed pattern with most patients achieving times below 90 minutes.

Figure 1: Distribution of Door-to-Balloon Times

Correlation Analysis

Spearman’s correlation analysis showed a strong positive correlation between consent time and D2B time (ρ = 0.89, p < 0.001). ED2CCU time had a moderate correlation (ρ = 0.45, p = 0.002), while ED2ECG and POSTCONSENT2B showed weak correlations (ρ = 0.15, p = 0.04; ρ = 0.20, p = 0.03). Figure 2 illustrates the relationship between consent time and D2B time.

Figure 2: Scatter Plot of Consent Time vs. Door-to-Balloon Time

Factors Associated with D2B Delays

Twenty-four patients (8%) had D2B times >90 minutes. Multivariable logistic regression identified consent time (OR: 1.12 per minute, 95% CI: 1.07–1.18, p < 0.001) and nighttime presentation (00:01–08:00) (OR: 2.95, 95% CI: 1.45–6.02, p = 0.003) as independent predictors of D2B delay. Female sex (OR: 1.85, 95% CI: 1.10–3.12, p = 0.02) and age >65 years (OR: 1.62, 95% CI: 1.05–2.50, p = 0.03) were associated with longer ED2ECG times. Table 3 summarizes these findings.

Table 3: Predictors of D2B Delay (>90 minutes)

Clinical Outcomes

In-hospital mortality was 3.7% (11 patients).

ed intra-aortic balloon pump use (15% vs. 5%, p = 0.01). Post-PCI TIMI 3 flow was achieved in 90% of patients. Figure 3 compares mortality by D2B time.

Figure 3: In-Hospital Mortality by D2B Time

This study demonstrates that the tertiary ED in North Kerala achieved a mean D2B time of 62 ± 14.5 minutes, surpassing the ACC/AHA guideline of ≤90 minutes [3]. This performance is competitive with global benchmarks (e.g., 59 minutes in the U.S. [13]) and superior to many Indian centers, where D2B times often exceed 80 minutes [14]. However, consent time and nighttime presentation emerged as significant barriers to optimal D2B times.

Consent Time Delays

Consent time (mean 25.4 minutes) was the primary driver of D2B delays, with a strong correlation (ρ = 0.89). This finding aligns with Subramanian et al. (2020), who noted that cultural factors, such as family involvement in decision-making and financial concerns, prolong consent in India [5]. Educational campaigns and trained counselors could expedite this process [9].

Nighttime Presentation

Nighttime presentation increased the odds of D2B delay nearly threefold, consistent with Bradley et al. (2006), who reported staffing shortages and slower coordination during off-hours [6]. Enhancing nighttime cath lab staffing and real-time feedback systems could address this issue [10].

Efficient Triage and Procedural Phases

The ED2ECG time (6.2 minutes) and POSTCONSENT2B time (13.9 minutes) met their respective goals in most cases, reflecting robust triage and cath lab efficiency. However, ED2CCU delays (16.8 minutes) suggest logistical challenges, such as limited CCU bed availability, as noted in prior studies [7].

Clinical Outcomes

The higher mortality in patients with D2B >90 minutes (12.5% vs. 2.9%) underscores the importance of timely reperfusion, consistent with Cannon et al. (2000) [8]. Prolonged TIT was associated with worse TIMI flow and increased mechanical support needs, highlighting the need for pre-hospital interventions [11].

Proposed Interventions

1. Streamlined Consent: Standardized consent forms and pre-hospital education could reduce delays [9].
2. Nighttime Optimization: Real-time data feedback and increased staffing could mitigate off-hour delays [10].
3. Pre-Hospital Strategies: EMS integration with pre-hospital ECG transmission could reduce TIT [11].
4. Logistical Improvements: Dedicated STEMI pathways and reserved CCU beds could minimize ED2CCU delays [12].

Limitations

This single-center study may not generalize to rural or smaller hospitals. Exclusion of transferred patients may underestimate system-wide delays. Manual time recording risks minor inaccuracies, though standardized protocols mitigated this. Socioeconomic factors influencing consent were not quantitatively assessed.

Future Directions

Regional STEMI networks, qualitative studies on consent delays, and pre-hospital ECG implementation warrant further exploration to enhance STEMI care in North Kerala.

The current study conducted in emergency department of North Kerala achieved a mean D2B time of 62 ± 14.5 minutes, with 92% of patients meeting the ≤90-minute guideline. Consent time and nighttime presentation were key barriers to optimal D2B times, contributing to worse outcomes. Targeted interventions addressing these factors could further improve STEMI care in resource-constrained settings.

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