Cardiac QTc interval characteristics before and after hematopoietic stem cell transplantation: an analysis of 995 consecutive patients at a single center

Abstract

Hematopoietic stem cell transplantation (HSCT) treats disorders affecting patients of all ages. We studied the rate-corrected cardiac QT interval (QTc) in 995 consecutive children and adults undergoing HSCT at the University of Minnesota. We sought to (1) describe QTc before and after HSCT; (2) describe the change in QTc after HSCT; (3) identify factors affecting QTc and its change; and (4) scrutinize an 'at risk' sub-cohort with a long QTc before HSCT. Pre HSCT: 952 (96%) patients had an evaluable electrocardiography (ECG); median QTc was 426 ms and depended upon disease necessitating transplant. Post HSCT: 506 (51%) patients had an evaluable ECG; median QTc was 441 ms. Intrapatient QTc change: 490 (49%) evaluable patients showed median QTc change (pre to post HSCT) of +16 ms (P<0.0001). At risk group: 68 patients were 'at risk' (long pre-HSCT QTc). In some, 'at-risk' status trended toward predictive of post-transplant nonrelapse mortality. QTc interval prolongation is evident in a large, diverse cohort undergoing HSCT at our institution. Prospective studies of this patient population may be warranted, particularly for 'at-risk' patients who demonstrate significant QTc prolongation both pre and post HSCT.

Figure 1

Histograms demonstrating frequency of mean QTc observed for the evaluable cohort in the pre-HSCT setting (A); frequency of mean QTc observed for the evaluable cohort in the post-HSCT setting (B); and the ΔQTc (change per patient of the QTc from pre- to post-HSCT) for those patients with evaluable ECGs both before and after transplantation.

Figure 2

Incidence of non-relapse mortality (NRM, death post-HSCT due to any cause other than progression of the underlying disease that necessitated transplantation): panel A shows NRM stratified by pre-HSCT "at risk" status; panel B shows NRM stratified by interplay between pre-HSCT "at risk" status and post-transplant mean QTc ["at risk" is defined as demonstrating long pre-HSCT mean QTc (males ≥ 460 ms, females ≥ 470 ms) without known HSCT-CI ≥ 3; long QTc post-HSCT defined as mean value ≥ 460 ms for males, and ≥ 470 ms for females]. Note: for patients without post-HSCT ECG, 2 year NRM was 3% for 32 "at risk" patients and 5% for 383 patients who were not "at risk."