Left ventricular wall thickness assessed by cardiac computed tomography and cardiac resynchronization therapy outcomes

Abstract

Aims: Up to 30% of selected heart failure patients do not benefit clinically from cardiac resynchronization therapy (CRT). Left ventricular (LV) wall thickness (WT) analysed using computed tomography (CT) has rarely been evaluated in response to CRT and mitral regurgitation (MR) improvement. We examined the association of LVWT and the ability to reverse LV remodelling and MR improvement after CRT.

Methods and results: Fifty-four patients scheduled for CRT underwent pre-procedural CT. Reduced LVWT was defined as WT <6 mm and quantified as a percentage of total LV area. Endpoints were 6-month clinical and echocardiographic response to CRT [New York Heart Association (NYHA) class, LV ejection fraction (LVEF), LV end-diastolic volume (LVEDV), and LV end-systolic volume (LVESV)], MR improvement and 2-year major adverse cardiac events (MACE). Patients were divided into three groups according to the percentage of LVWT <6 mm area: ≤20%, 20-50%, and ≥50%. At 6 months, 75%, 71%, and 42% of the patients experienced NYHA improvement in the ≤20%, 20-50%, and ≥50% group, respectively. Additionally, ≤20% group presented higher LVEF, LVEDV, and LVESV positive response rate (86%, 59%, and 83%, respectively). Both 20-50% and ≥50% groups exhibited a lower LVEF, LVEDV, and LVESV positive response rate (52% and 42%; 47% and 45%; and 53% and 45%, respectively). Additionally, ≥25% of LVWT <6 mm inclusive of at least one papillary muscle insertion was the only predictor of lack of MR improvement. Lastly, ≥50% group experienced significantly lower 2-year MACE survival free probability.

Conclusion: WT evaluated using CT could help to stratify the response to CRT and predict MR improvement and outcomes.

Clinical trial registration: NCT01097733.

Keywords: Cardiac resynchronization therapy; Computed tomography; Heart failure; Left ventricular wall thickness; Mitral regurgitation; Outcome; Response to cardiac resynchronization therapy.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2019. For permissions, please email: journals.permissions@oup.com.

Figures

Figure 1

Example of left ventricular wall thickness segmentation using the ADAS software in patients with ≤20%, 20–50%, and ≥50% of LV WT A) Antero-posterior view. (B) Postero-anterior view. (C) Lateral view. (D) Inferior view. LV, left ventricular; WT, wall thickness.

Figure 2

Clinical response to CRT from baseline to 6 months. (A) Global assessment at 6 months. (B) Six-minute walk distance evolution between baseline and 6 months. CRT, cardiac resynchronization therapy.

Figure 3

Electrocardiographic and echocardiographic response to CRT from baseline to 6 months. (A) QRS duration change from baseline to 6 months. (B) Individual changes in LVEF from baseline to 6 months. (C) Change in LVEDV and LVESV from baseline to 6 months. CRT, cardiac resynchronization therapy; LVEF, left ventricular ejection fraction; LVESV, left ventricular end-systolic volume; LVEDV, left ventricular end-diastolic volume.

Figure 4

(A and B) Illustrative examples of WT segmentation and PM insertion. (A) Patient with 45% of LVWT <6 mm and PM insertion in normal WT area who experienced MR improvement at 6 months. (B) Patients with 46% of LVWT <6 mm and posterior PM inserted in reduced WT area without MR improvement. (C) LV segmentation and location of each reduced WT segments in a patient with or without MR improvement. Star indicates anterior PM insertion; Arrow indicates posterior PM insertion. LVWT, left ventricular wall thickness; MR, mitral regurgitation; PM, papillary muscle; WT, wall thickness.

Figure 5

MACE free survival probability. MACE, major adverse cardiac events.