Comprehensive analysis of the impact of primary percutaneous coronary intervention on patients with ST-segment elevation myocardial infarction

Abstract

This comprehensive analysis by Saeed and Faeq investigates the impact of primary percutaneous coronary intervention (pPCI) on mortality among patients with ST-segment elevation myocardial infarction (STEMI) at the Erbil Cardiac Center. Analyzing data from 96 consecutive STEMI patients, the study identified significant predictors of in-hospital mortality, emphasizing the critical impact of time of hospital arrival post-symptom onset on overall prognosis. Findings indicate that factors such as atypical presentation, cardiogenic shock, chronic kidney disease, and specific coronary complications are associated with higher mortality rates. The study underscores the necessity of prompt medical intervention for improving survival outcomes in STEMI patients, especially in the high-risk subgroup. This research offers valuable insights into optimizing STEMI management and enhancing patient survival rates through effective and timely pPCI.

Key Words: ST-segment elevation myocardial infarction; Primary percutaneous coronary intervention; Mortality predictors; Timely hospital arrival; Cardiogenic shock

Core Tip: This study by Saeed and Faeq reveals the significant impact of timely primary percutaneous coronary intervention on mortality reduction in ST-segment elevation myocardial infarction patients. The analysis showed that chronic kidney disease, specific culprit coronary lesions, and an atypical presentation characterized by presence of either syncope, cardiogenic shock, or ventricular arrhythmias on arrival were predictive of post-percutaneous coronary intervention mortality.

TO THE EDITOR

In this letter, we present our comments on the article by Saeed and Faeq[1]. This article addresses a critical aspect of cardiovascular emergency care, focusing on the outcomes of primary percutaneous coronary intervention (pPCI) in patients with ST-segment elevation myocardial infarction (STEMI) treated at the Erbil Cardiac Center.

RESULTS/DISCUSSION

The study[1] is premised on the assertion that reduction in time from symptom onset to hospital arrival can significantly improve prognosis of STEMI patients. The authors’ hypothesis is evidently a strength of this study owing to the extensive body of medical literature supporting this assertion. It, therefore, stands to reason that the current guidelines endorse a door-to-balloon time of less than 90 minutes, as shorter times significantly correlate with reduced 1-year mortality. The authors analyze data from 96 patients with STEMI to tease out factors predictive of inpatient mortality and 30-day mortality post-discharge. Of the 96 patients, 92.7% (89) presented with typical ischemic chest pain, whereas, the remainder had an atypical presentation comprising syncope, ventricular arrhythmias, cardiogenic shock (CS), or cardiac arrest. Patients with certain culprit lesions and an atypical presentation on arrival had markedly higher mortality.

Several studies have shown that moderate to severe chronic kidney disease (CKD) is associated with adverse outcomes after uncomplicated primary PCI[2-5]. The authors[1] arrived at a similar conclusion, however, the findings lacked granularity. Differentiating mortality rates across different stages of CKD would have ascribed greater predictive power to this variable and offered insight into the impact of renal dysfunction, making it a robust parameter in risk-stratification of pPCI patients. Authors also mentioned that higher serum creatinine was statistically associated with a higher risk for mortality. This is analogous to the conclusion drawn for the association between presence of CKD and mortality previously. It is important to note here that serum creatinine, per se, is a flawed surrogate marker as it is affected by lean body mass, dietary protein intake, anabolic drug/bodybuilding supplement consumption, etc. Reliance on other parameters (namely cystatin C), that are less prone to such fallacies, could help address the aforementioned shortcomings. Also, it would be interesting to know the rationale for the analysis that compares varying amounts of white cell count with inpatient and 30-day mortality rates.

Pre-procedural A1c levels didn’t show a statistically significant relationship with mortality in this study[1]. Historically, higher A1c values have been associated with increased risk for major adverse cardiovascular events, but outcomes on mortality are mixed with some studies demonstrating higher mortality even with stringent glycemic control[3,4]. Although the authors state that CS on presentation was an adverse prognostic marker, the timing of development of new in-hospital CS events, and early vs late mechanical circulatory support initiation is unclear. These estimates have been shown to be independent prognostic markers in some studies[6,7]. Therefore, inclusion of this information could have been conducive to the overall analyses. Also, subgroup analyses involving patients with atypical presentation who are inherently at heightened risk for adverse overall outcomes, or conduction of a multivariate analysis that adjusts for the potential confounding effect of baseline illness severity could engender a more reliable assessment of prognostic predictors in this cohort.

Presence of anemia did not confer higher mortality in this study[1]. Notably, all participants had a hemoglobin level greater than 11 g/dL. This interesting observation is in line with the contemporary data [TRICS, REALITY, MINT] surrounding transfusion thresholds in acute coronary syndromes, which hints at improvement in cardiovascular outcomes with liberal transfusion strategy as opposed to restrictive strategy[8-10]. Patients in this study[1] were above the transfusion threshold of 10 g/dL and were optimized from a hematocrit standpoint, potentially explaining the negative association between anemia (“mild”) and mortality.

The study[1] also elucidates survival outcomes associated with location of culprit lesions. Left circumflex, left anterior descending (LAD), and obtuse marginal lesions conferred higher inpatient mortality, whereas only LAD lesions resulted in higher 30-day mortality post-discharge. Triple-vessel disease accounted for the majority of inpatient deaths (P < 0.001). Left main stem disease was also significantly associated with inpatient mortality (P < 0.05). Notably, 30-day mortality post-discharge was noted in patients with triple vessel disease only (P < 0.05). It would have been interesting to analyze the relationship between type of vascular access (radial vs femoral) and stent used with incident mortality. Studies have shown that transfemoral access (TFA) is associated with statistically greater need for critical care support, and 30-day mortality in patients with cardiogenic shock. Transradial approach yields successful PCI outcomes with lesser incidence of adverse events when compared with TFA[11]. Additionally, newer generation drug eluting stents (DES) are associated with lower mortality when compared with older generation DES[4].

Since patients with atypical symptomology have suboptimal short and long - term outcomes, it is important to note that this often involves prolonged out-of-hospital cardiac arrest times or ventricular dysrhythmias with resultant adverse neurological sequelae[12]. This, in turn, is tied to the paucity or lack of volunteer training in cardiopulmonary resuscitation (CPR) and automated external defibrillator (AED) use, which varies widely across different jurisdictions. Studies have shown that implementation of a structured response plan can double survival rates if bystanders are well-trained and equipped to utilize AED in an accurate and timely fashion. Therefore, universal AED access and meticulous CPR training of laymen is indubitably paramount to improving survival rates, especially for the high-risk subset. Postperfusion STEMI patients are routinely triaged to cardiac intensive care units. However, it seems that stable patients may not necessarily require intensive care treatment. Clinicians should predicate their decision on the overall clinical risk profile and the anticipation of need for critical care treatments. Several predictive variables can assist in risk-stratifying post-perfusion patients, allowing for timely institution of appropriate therapies along with optimal use of resources.

Overall, the authors[1] did a commendable job at determining prognostic variables in a sizable cohort of STEMI patients undergoing pPCI. Their findings further underscore the need for early risk-stratification of high-risk subsets and concomitant correction of metabolic derangements and organ dysfunction. Optimization of survival rates in this cohort requires prompt institution of modalities namely renal replacement, blood transfusion, mechanical circulatory support, inotropes, mechanical ventilation, etc., based on the overall risk profile of the patient as discussed herein.