Utility of Residual Syntax Score to Predict Outcome After Acute Myocardial Infarction

A- Study Design: Prospective cross-sectional analytic study

B- Study Protocol: After attaining written informed consents from eligible STEMI/NSTEMI patients for participation in this observational study, data collection will be as follows: -

1. Targeted history taking emphasizing on:

• Age of the patient, gender, and other risk-factors as hypertension, diabetes mellitus, smoking, substance abuse, dyslipidemia or family history of premature CAD.
• Symptoms as chest pain and time of onset, previous CAD related symptoms, therapies or revascularization procedures.
• Any relevant comorbid conditions.
• Time delays labelled as patient related delay, door-to-first medical contact, any delays of transfer, door-to-needle or -to-wire crossing will be recorded.

1. Examination: Targeted physical examination of the patients with special emphasis on heart rate, blood pressure at presentation, Killip class (I-to-IV), signs suggestive of mechanical complications (new murmurs, pulmonary edema or cardiogenic shock). Patient weight and height will be collected to assess for overweight and/or obesity.
2. Standard 12-leads surface electrocardiogram (ECG): It will be obtained to as part of initial diagnosis, identify rhythm disturbances (heart block or any other arrythmias). Non-standard ECG (right or posterior leads positioning) would be ordered as appropriate.
3. Echocardiography: A rapid targeted bed-side study will be performed pre-cath as appropriate to assess LV-systolic function, regional wall motion abnormalities and any mechanical complication. Priority will be clearly for reperfusion, thus if the bed-side study would result in further delay, it will not be performed. All patients will have a formal and complete echo study before hospital discharge.
4. Laboratory data: Venous blood sample will be obtained from all patients for biochemistry analysis. Cardiac biomarkers, complete blood count, coagulation profile, liver and kidney function testing, lipid-profile, CRP and glycated hemoglobin (HbA1c).
5. Coronary angiography:

Coronary angiography and PCI is considered the gold-standard modality of revascularization for ST-segment Elevation myocardial infarction and is recommended within 24 hours for the majority patients presenting with NSTEMI.

Coronary angiography and PCI will be performed according to standard protocol. Culprit vessel, culprit lesion type and characteristics, initial and final TIMI flow, presence and number of non-culprit lesions will be collected and tabulated. Residual syntax score (rSS), as a surrogate for non-culprit atherosclerotic disease burden, will be equated as the conventional syntax score but subtracting the score of the culprit lesion(s) that have been passivated in the index procedure.

C- Follow-up Patients will be followed up for at least six-months to ensure compliance to medical therapy and life style interventions, and to report outcome measures accurately, including major adverse cardiac events (MACE), rehospitalization, target lesion revascularization, other unplanned revascularization and/or heart failure.

D- Data analysis By the end of the study period, the residual syntax score (rSS) will be used as a stratification tool to assess its correlation with outcome parameters.