{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,10]],"date-time":"2026-02-10T18:33:25Z","timestamp":1770748405582,"version":"3.49.0"},"reference-count":16,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2022,9,19]],"date-time":"2022-09-19T00:00:00Z","timestamp":1663545600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Physiol."],"abstract":"<jats:p><jats:bold>Introduction:<\/jats:bold> Differentiating idiopathic premature ventricular contractions (PVCs) originating from the right and left ventricular outflow tracts with a left bundle branch block (LBBB) morphology is relevant to catheter ablation planning and important for lowering the risk of complications. This study established a novel electrocardiographic (ECG) criterion to discriminate PVCs originating from the septum of the right ventricular outflow tract (s-RVOT) and those originating from the aortic sinus cusp of the left ventricular outflow tract (LVOT-ASC).<\/jats:p><jats:p><jats:bold>Methods:<\/jats:bold> A total of 259 patients with idiopathic PVCs originating from ventricular outflow tract with a LBBB pattern who underwent successful catheter ablation were retrospectively included. Among them, the PVCs originated from the s-RVOT in 183 patients and from the LVOT-ASC in 76 patients. The surface ECGs of the PVCs and sinus beats were analyzed using an electronic caliper. The R-S difference index in the precordial leads was calculated as V2R + V3R + V4R \u2212 V1S.<\/jats:p><jats:p><jats:bold>Results:<\/jats:bold> PVCs originating from both the s-RVOT and LVOT-ASC displayed an inferior axis (dominant R waves in leads II, III, and aVF). Compared with the s-RVOT group, the R-wave amplitudes on leads II, III, and aVF were significantly larger in the LVOT-ASC group (<jats:italic>p<\/jats:italic> &amp;lt; 0.001, <jats:italic>p<\/jats:italic> &amp;lt; 0.003, and <jats:italic>p<\/jats:italic> &amp;lt; 0.001, respectively). Compared to the LVOT-ASC group, the s-RVOT group showed smaller R-wave amplitudes on leads V1\u2013V6 (<jats:italic>p<\/jats:italic> = 0.021, <jats:italic>p<\/jats:italic> &amp;lt; 0.001, <jats:italic>p<\/jats:italic> &amp;lt; 0.001, <jats:italic>p<\/jats:italic> &amp;lt; 0.001, <jats:italic>p<\/jats:italic> &amp;lt; 0.001, and <jats:italic>p<\/jats:italic> &amp;lt; 0.001, respectively) and larger S-wave amplitudes on leads V1\u2013V3 (<jats:italic>p<\/jats:italic> &amp;lt; 0.001, <jats:italic>p<\/jats:italic> &amp;lt; 0.001, and <jats:italic>p<\/jats:italic> &amp;lt; 0.001, respectively). Lead V3 was the most common transitional lead in both groups. Analysis of the receiver operating characteristic curve showed that the R-wave amplitude on lead V3 had the largest area under the curve (AUC) of 0.856 followed by the R-wave amplitudes on leads V4 (0.834) and V2 (0.806). The AUC of the R-S difference index was 0.867. An R-S difference index greater than 20.9 predicted an LVOT-ASC origin with 73.7% sensitivity and 86.3% specificity. This index is superior to previous criteria in differentiating PVCs with LBBB morphology and inferior axis originating from s-RVOT vs. LVOT-ASC.<\/jats:p><jats:p><jats:bold>Conclusions:<\/jats:bold> The R-S difference index in precordial leads is a useful new ECG criterion for distinguishing LVOT-PVCs from RVOT-PVCs with LBBB morphology.<\/jats:p>","DOI":"10.3389\/fphys.2022.1002926","type":"journal-article","created":{"date-parts":[[2022,9,19]],"date-time":"2022-09-19T04:25:25Z","timestamp":1663561525000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":4,"title":["The R-S difference index: A new electrocardiographic method for differentiating idiopathic premature ventricular contractions originating from the left and right ventricular outflow tracts presenting a left bundle branch block pattern"],"prefix":"10.3389","volume":"13","author":[{"given":"Lei","family":"Zhao","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ruibin","family":"Li","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jidong","family":"Zhang","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ruiqin","family":"Xie","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jingchao","family":"Lu","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jinming","family":"Liu","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Chenglong","family":"Miao","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Wei","family":"Cui","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1965","published-online":{"date-parts":[[2022,9,19]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"2255","DOI":"10.1016\/j.jacc.2011.01.035","article-title":"The V(2) transition ratio: A new electrocardiographic criterion for distinguishing left from right ventricular outflow tract tachycardia origin","volume":"57","author":"Betensky","year":"2011","journal-title":"J. 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