Pavri Behzad B, Goodman Jack, Frankel Eitan
Division of Cardiology, Department of Medicine, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania.
Division of Cardiology, Department of Medicine, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania.
Heart Rhythm. 2025 May 19. doi: 10.1016/j.hrthm.2025.05.025.
Right bundle branch block (RBBB) pattern does not imply normal left bundle branch conduction but may simply indicate a more diseased right bundle branch. In lead I, initial rapid QRS forces represent left ventricular depolarization and the terminal S wave represents slower right ventricular depolarization. We postulated that slurring of initial forces with resulting narrowing of the S-wave duration and a smaller S/QRS ratio may be associated with a need for a permanent pacemaker (PPM).
This study aimed to assess the S/QRS ratio in lead I as an electrocardiogram measurement associated with a need for PPM.
We measured the PR interval, QRS axis, QRS duration (QRS), S-wave duration in lead I, and S/QRS ratio in 2 groups of patients, all with RBBB: (1) controls, patients who did not require PPM, and (2) cases, patients who received PPM for alternating bundle branch block, Mobitz 2/complete heart block, or bifascicular block with abrupt syncope. Immediate preimplant and oldest available electrocardiograms that showed RBBB were analyzed.
A total of 218 patients with RBBB were included. For controls (n = 109), over a follow-up of 90.16 months (range 4.5-347), QRS increased from 145.2 to 146.7 ms (P = .67), and the S/QRS ratio decreased from 0.59 to 0.57 (P = .02). For cases (n = 109), over follow-up of 89.22 months (range 2.21-262.75), QRS increased from 139.9 to 147.6 ms (P < .001), and the S/QRS ratio decreased from 0.52 to 0.43 (P < .001). On multivariable analyses, an S/QRS ratio of < 0.56 was associated with a need for PPM (odds ratio 6.87, confidence interval 3.87-12.67, P < .001).
In patients with RBBB, narrowing of the S wave in lead I with an S/QRS ratio of < 0.56 is associated with increased need for PPM, even after adjusting for QRS.
右束支传导阻滞（RBBB）图形并不意味着左束支传导正常，而可能仅仅表明右束支病变更严重。在I导联中，初始快速QRS波力代表左心室去极化，而终末S波代表较慢的右心室去极化。我们推测，初始波力顿挫导致S波时限变窄以及S/QRS比值减小可能与需要植入永久性起搏器（PPM）有关。
本研究旨在评估I导联中的S/QRS比值作为与PPM需求相关的心电图测量指标。
我们测量了两组均为RBBB患者的PR间期、QRS电轴、QRS时限（QRS）、I导联中的S波时限以及S/QRS比值：（1）对照组，即不需要PPM的患者；（2）病例组，即因交替性束支传导阻滞、莫氏Ⅱ型/完全性心脏传导阻滞或伴有突然晕厥的双分支阻滞而接受PPM的患者。分析了显示RBBB的植入前即刻和可获得的最旧心电图。
共纳入218例RBBB患者。对照组（n = 109），在90.16个月（范围4.5 - 347个月）的随访中，QRS从145.2 ms增加到146.7 ms（P = 0.67），S/QRS比值从0.59降至0.57（P = 0.02）。病例组（n = 109），在89.22个月（范围2.21 - 262.75个月）的随访中，QRS从139.9 ms增加到147.6 ms（P < 0.001），S/QRS比值从0.52降至0.43（P < 0.001）。多变量分析显示，S/QRS比值< 0.56与需要PPM相关（比值比6.87，置信区间3.87 - 12.67，P < 0.001）。
在RBBB患者中，I导联S波变窄且S/QRS比值< 0.56与PPM需求增加相关，即使在调整QRS后依然如此。
