European Journal of Cardiovascular Medicine

Intravenous thrombolysis is an important reperfusion strategy from long time in ST elevation myocardial infarction (STEMI) patients, especially when primary percutaneous coronary intervention (PCI) cannot be offered. Although primary PCI is the first line of therapy in patients with acute myocardial infarction, yet it is not frequently practiced at all centers due to various factors like non-availability of the Cath lab, delayed presentation of the patients, or the cost factor involved in it.¹ The ultimate goal of reperfusion in acute STEMI is myocardial tissue perfusion, whether it is due to primary PCI or due to thrombolytic therapy. Some patients develop spontaneous recanalization of the occluded infarct related artery.

Failed reperfusion after thrombolytic therapy is common and signifies worse outcomes compared to patients with successful thrombolysis.² Various studies have reported inconsistent rates of failed thrombolysis in STEMI patients for both fibrin-specific (reteplase, tenecteplase) and non-fibrin-specific (streptokinase) thrombolytic agents.^3,4 Some studies suggested factors predicting failed thrombolysis in STEMI patients, such as, anterior territory infarct, higher Killip class, longer window period, longer door-to-needle time, hyperglycaemia on presentation, pre-existing diabetes and higher thrombolysis in myocardial infarction (TIMI) score.^4,5,6,7

Many authors have suggested different criteria for successful or failed thrombolysis. Most of them have stated successful thrombolysis as ST segment resolution in the lead with maximum ST segment elevation on presentation, with greater than 50% resolution of ST segment after 60-90 minutes of thrombolytic therapy, along with resolution of symptoms.⁸ 2023 ESC Guidelines for the management of acute coronary syndromes have suggested ST-segment resolution >50% at 60–90 min, typical reperfusion arrhythmia and disappearance of chest pain associated with hemodynamic stability as the criteria for successful reperfusion. Rescue PCI is recommended for failed fibrinolysis (i.e., ST-segment resolution <50% within 60–90 min of fibrinolytic administration) or in the presence of hemodynamic or electrical instability, worsening ischemia, or persistent chest pain.⁹

In our study we aim to study the clinical and coronary angiographic profile in patients of acute ST elevation myocardial infarction having failed thrombolysis and compare it with those having successful thrombolysis.

This was a cross sectional, observational, single centre study, conducted from January 2024 to December 2024, in which 100 acute STEMI patients presenting within window period and receiving thrombolytic therapy were recruited from the Department of Cardiology, SMS Hospital, Jaipur after the institutional ethical committee approval. All patients underwent coronary angiography and reperfusion therapy during the same admission period. Those having contraindication for thrombolysis or presenting outside the window period for receiving thrombolytic therapy or undergoing primary percutaneous coronary intervention were excluded. The results were analysed statistically using SPSS (Statistical Package for the Social Sciences) version 26.0 software (SPSS Inc) with p value <0.05 considered statistically significant.

A total of 100 acute STEMI patients were studied who received thrombolytic therapy and underwent coronary angiography. The mean age of the subjects was 57.92 ± 12.36 years (range 28 – 81 years) with 80 males and 20 females. The mean duration of presentation or the window period was 5.89 hrs. 54% had anterior wall myocardial infarction (AWMI). Amongst the risk factors for coronary artery disease, smoking was present in 58% and 20% were diabetics. Tenecteplase was the most common thrombolytic agent used (35%), followed by streptokinase in 31%, alteplase in 19% and reteplase in 15%. Out of the 100 patients enrolled in this study, 81% had successful thrombolysis whereas 19 patients had failed thrombolysis. Tables 1-3 compares the clinical and biochemical profile of patients between failed and successful thrombolysis groups. 50% of patients who presented after 9 hrs of symptom onset had failed thrombolysis whereas only 20.7% of those presenting within 3 hrs had failed thrombolysis. 27.8% patients of AWMI had failed thrombolysis whereas only 8.7% patients with inferior territory involvement had failed thrombolysis.

Table 1: Clinical profile comparison in Failed vs Successful thrombolysis patients

Table 2: Complications in failed and successful thrombolysis groups

Table 3. Biochemical profile of Failed vs Successful thrombolysis patients

Coronary Angiography findings

Amongst 100 patients, 30% had single vessel involvement, 35% had double vessel and 24% had triple vessel involvement. Left main involvement was seen in 9% cases. (Figure 1) In 19 patients having failed thrombolysis, single vessel, double vessel and triple vessel disease was seen in 6, 6 and 6 patients respectively with 1 patient having left main with single vessel disease. On comparing the culprit artery involved, 94.1% cases of LCX involvement and 89.6% cases of RCA involvement had successful thrombolysis, whereas only 72.2% cases of LAD involvement had successful thrombolysis. (p = 0.049, table 4) Table 5 summarizes the angiographic profile of the patients having successful and failed thrombolysis. All patients having failed thrombolysis had critical stenosis in one of the epicardial arteries with TIMI flow <3, and subsequently underwent coronary angioplasty in form of rescue percutaneous coronary intervention. 90.1% patients having successful thrombolysis required revascularization either via percutaneous transluminal coronary angioplasty or coronary artery bypass surgery.

Figure 1. Coronary artery involvement

Figure 2: Culprit artery involved in successful and failed thrombolysis groups

Table 4. Comparison of culprit artery involved in Failed vs Successful thrombolysis

Table 5. Angiographic Profile of Failed and Successful thrombolysis groups

Throughout the world, 30%–70% of patients with STEMI receive thrombolysis as the initial reperfusion therapy.¹¹ This study consisted of 100 STEMI patients who received fibrinolytic therapy as the primary reperfusion strategy, in which 19 patients had failed thrombolysis who were further subjected to rescue PCI. The mean age of patients in the failed thrombolysis group was 52.27 ±11.87 years. There was no statistically significant difference in age, gender, religion or risk factors such as smoking, hypertension and diabetes between the failed and successful thrombolysis groups.

Total ischemic time (from symptom onset to reperfusion therapy) or the window period is the most important factor in achieving the best possible outcomes in STEMI.¹² The mean time from onset of symptoms to first medical contact was 5.5 hours in patients in the successful thrombolysis group, whereas it was 7.3 h in patients in the failed thrombolysis group. This was consistent with the findings in other studies where shorter window period has better chances of successful thrombolysis. ^5,6,7

AWMI was the most common territory of infarction, and the left anterior descending (LAD) artery the most common infarct-related artery. 27.78% patients of AWMI had failed thrombolysis whereas 91.3% patients of IWMI had successful thrombolysis. This difference was statistically significant and some studies have implicated anterior territory infarction as a predictive factor for failed thrombolysis.^5,13 Complications in acute myocardial infarction including atrioventricular blocks, ventricular arrhythmias and heart failure were seen in some cases but their number were not significant to assess the predilection for successful or failed thrombolysis. (Table 2)

In our study 31.5% patients with failed thrombolysis had triple vessel involvement whereas 27.1% patients in successful thrombolysis group had triple vessel disease. Left main involvement was seen in 9% cases. LCX and RCA occlusions had higher proportions of successful thrombolysis than LAD. Durdana S et al. in their study also showed least angiographic success of thrombolysis with LAD as the infarct-related artery.¹⁴ These findings though are not consistent with some studies¹⁵ and needs further evaluation regarding predilection of LAD thrombus for failed thrombolysis.

Different thrombolytic agents were used in our study but no statistically significant difference was observed among them. Although the GUSTO trial¹⁶ showed better angiographic results with Alteplase compared to streptokinase, other studies and meta-analysis showed similar clinical outcomes with various thrombolytic agents.^{17, 18}

Coronary angiographic findings correlated with the clinical setting with 19% patients who received thrombolytic therapy failed to achieve TIMI 3 flow. Only 10% patients with successful thrombolysis had non-critical CAD. Angiographically significant lesion was found in around 90% patients having successful thrombolysis who were either subjected to stenting or advised for complete revascularized in form of multivessel PCI or CABG.

The main limitation of this study was small sample size because subjects undergoing primary PCI and those without angiographic data were excluded. Coronary imaging was not used which could further help in identifying plaque characteristics or vulnerability. There was a lack of follow up and the long-term outcomes between the two groups were not assessed.

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