Pharmaco-Invasive Therapy for Acute ST-Elevation Myocardial Infarction.-A Viable Alternative to Primary Percutaneous Coronary Intervention

Primary percutaneous coronary intervention (pPCI) is considered as the preferred treatment for acute ST-Elevation myocardial infarction (STEMI). However, its availability is limited to less than 10% in rural and sub urban population in India (1). Therefore, Pharmaco-Invasive Therapy (PIT) (Thrombolysis first followed by planned coronary stenting) as an alternative to pPCI for acute STEMI has more recently been explored. A retrospective observational study of 60 patients with acute STEMI treated at the Dedicated Heart Attack Treatment Centre of SKY Hospital & Research Centre, Imphal, India over a period of 2 years has shown that Pharmaco-Invasive Therapy improved survival of patients with acute STEMI to 100% and increased Left Ventricular Ejection Fraction (LVEF) by 5.08% at the time of discharge and may be used as a viable alternative to pPCI in the treatment of patients with acute STEMI when pPCI cannot be performed within recommended time.


Introduction
Cardiovascular disease is World's first fatal disease. It contributes to 30% of global mortality and 10% of the global disease burden [2,3]. Myocardial Infarction (MI) is one of the five main manifestation of coronary artery disease (CAD) [4]. In epidemiological studies, the incidence of myocardial infarction in a population can be used as a proxy for estimating the CAD burden [4].
Acute ST-Elevation myocardial infarction results from sudden total or subtotal occlusion of one or more coronary artery [5]. Early revascularisation of the occluded coronary artery is the principle of treatment for such patients presenting within 12 hours of onset of symptoms, preferably within 30 minutes of arrival to hospital. Primary percutaneous coronary intervention is the recommended treatment strategy for acute STEMI, if the same can be performed within 120 minutes from the first medical contact (FMC) [6]. However, there are several hardles to be overcome to achieve this target in many areas of the World. Availability of PCI facility with skilled manpower is limited to few centres of big cities [5]. Furthermore, to do timely pPCI for acute STEMI in many such centres may not always be practically possible 24 hours a day. The aim of this paper is to study if Pharmaco-Invasive Therapy is as effective as pPCI for acute STEMI

Material and Method
The present study was conducted at SKY Hospital & Research Centre, Imphal, India. Data of eighty patients with acute STEMI admitted over 2 years ending February 2020 were collected. Out of this, 60 patients who received Pharmaco-Invasive Therapy were included in the study. Patients with acute STEMI who presented with acute stroke, multi-organ failure or who died within one hour of presentation to the hospital were excluded from the study. In the study, the remaining 60 patients whose coronary angiogram showing > 70% residual diameter stenosis of the culpil lesion after Thrombolytic Therapy were included. The time interval in minutes between the arrival at the hospital to the start of thrombolysis was obtained. The time interval in hours from the time of thrombolysis to the time of coronary stent implantation of each case has also been obtained.

ISSN: 2641-0419
Page 2 of 3 2016 providing 24 hours emergency service specifically for patients with suspected M.I. Our HAC Team consists of Consultant Cardiologist/middle grade Cardiologist on site, other Emergency Medical Officers, well trained nurses and technicians. In the HAC, ECG was given to all the patients within 5 minutes of presentation to the Emergency Room (ER). Loading dose of dual anti-platelet (DAP) therapy was given within 15 minutes to all the patients who were diagnosed with STEMI. After ruling out any contraindication (such as increased risk of bleeding), thrombolysis was given using fibrin specific fibrinolytic agents. Injection reteplase [dosage: 10 units intravenous (IV) over 2 minutes (1st dose), followed by 10 units IV over 2 minutes (2nd dose) after 30 minutes], or Injection tenecteplase (dosage 30 mg IV for patients weighing less than 60 kg, 35 mg IV for patients weighing 60 kg -69 kg, 40 mg IV for patients weighing 70 kg -79 kg, 45 mg IV for patients weighing 80 kg -89 kg, 50 mg IV for patients weighing ≥ 90 kg ) [7]. All thrombolysed patients also received Inj. enoxaparin as per protocol.

Result
All patients received thrombolysis within 12 hours of admission, majority 40 (76%) within 30 minutes (Table-1) and coronary stenting within 10 days. All patients with STEMI received Echocardiogram to estimate Left Ventricular Ejection Fraction (LVEF) on admission and at discharge (Figure-1).

Mean Median Std. Deviation
Door-to-ECG 5 minutes 5 minutes 0 Door to dual antiplatelet (DAP) 14 minutes 10 minutes 14 Door-to-thrombolysis 25 minutes 20 minutes 26  Following our discharge protocol which included, among others, mobilization for at least 100 steps on level without angina and dyspnea, all patients who received the PIT were discharged home with a 12 days median length of hospital stay.
With respect to survival rate, all the sixty patients who received Pharmaco-Invasive Therapy during the study period survived at the time of discharge.

Discussion
Revascularization of an occluded coronary artery as early as possible is the principle of treatment for patients with acute STEMI [5]. Timely performed primary PCI is considered as the preferred treatment strategy for acute STEMI. When this treatment cannot be provided within the recommended time, Pharmaco-Invasive Therapy has been tried with comparable outcome [8]. The STREAM trial [8] clearly showed that PIT and pPCI were comparable in the rate of primary composite end points (death, reinfarction, cardiogenic shock, heart failure at 30 days) in the treatment of acute STEMI if pPCI could not be performed within 60 minutes of presentation to Emergency Department. The STEPP-AMI study [9] also demonstrated that Pharmaco-Invasive Therapy is not inferior to primary PCI in the treatment of acute STEMI with similar outcome at 2 years of follow up. However, it remains unclear whether late presenters will benefit from the STREAM like PIT. In our study it is possible that establishment of Dedicated culprit lesion which subsequently got balloon-dilated and stented. It was also observed that there was no case of failed thrombolysis in our study-population in comparison to 12.1% in STEPP-AMI study.

Conclusion
Pharmaco-Invasive Therapy for acute STEMI in a well fashioned Dedicated Heart Attack Centre has shown improved survival along with increased left ventricular ejection fraction. This treatment strategy may be considered as a viable alternative to primary PCI for emergency treatment of acute STEMI in many developing countries where timely primary PCI cannot be performed.
Large clinical trials may help further substantiate the finding of the present study.