Perimitral atrial tachycardia (PMAT) is the most frequent type of iatrogenic atrial tachycardia (AT) after atrial fibrillation (AF) ablation. Vein of Marshall ethanol infusion (EIVOM) is a promising technique in mitral isthmus (MI) ablation. A total of 165 patients with PMAT were divided into three groups according to ablation strategies, including RF only group (n=89), RF-EIVOM group (initial RF ablation with adjunctive EIVOM, n=28), and EIVOM-RF group (first-step EIVOM with touch-up RF ablation, n=48). Acute and follow-up procedure outcomes were evaluated. PMAT terminated in 89.9%, 89.3%, and 93.7% of patients in RF only, RF-EIVOM and EIVOM-RF groups, respectively (p=.715), with complete MI block achieved in 80.9%, 89.3%, and 95.8% of patients (EIVOM-RF vs. RF only, p=.012). First-step utilization of EIVOM was associated with a significant shortening of RF ablation time at MI (EIVOM-RF 2.1±1.3min, RF only 7.9±5.9min, RF-EIVOM 6.8±5.8min; p<.001) and a decrease in the proportion of patients need ablation within coronary sinus (CS, EIVOM-RF 14.6%, RF only 61.8%, RF-EIVOM 64.3%; p<.001). After a mean follow-up of 12.1±6.2 months, AF/AT recurred in 39 (43.8%), 6 (21.4%), and 12 (25.0%) patients in RF only, RF-EIVOM, and EIVOM-RF group (RF-EIVOM vs. RF only, p=.026; EIVOM-RF vs. RF only, p=.022). EIVOM was associated with an enhanced acute MI block rate as well as reduced AF/AT recurrence. First-step utilization of EIVOM promises to significantly simplify the RF ablation process. PMAT is the most common type of iatrogenic AT after AF ablation procedures. EIVOM contributed to a higher acute MI block rate and lower arrhythmia recurrence risk during follow-up. First-step utilization of EIVOM significantly reduced the need for radiofrequency ablation at MI and inside CS with the advantage of creating a homogenous, transmural lesion and eliminating epicardial connections.