QT DISPERSION AS A MARKER OF RISK IN PATIENTS AWAITING HEART-TRANSPLANTATION

Objectives. The objectives of this study were to determine whether a s ignal-averaged electrocardiogram (SAECG) or measurement of interlead v ariability of QT intervals on an electrocardiogram (ECG) obtained at t he time of wait-listing could provide prognostic value with respect to cardiac death during the waiting period. Background. Because heart tr ansplantation is a life-saving but limited resource, there remains an urgent need to identify those patients at greatest risk of dying while awaiting heart transplantation as part of the strategy to optimize th e allocation of donor organs to those in greatest need, This study was undertaken to prospectively identify clinical, ECG or SAECG variables that might predict mortality during the waiting period. Methods. Of 1 08 consecutive patients referred for heart trans plant evaluation, 80 were placed on a waiting list, at which time a standard 12-lead ECG an d a SAECG were recorded. In this cohort of 80 patients, QT dispersion was characterized from the 12-lead ECG as either the maximal-minimal Q T interval (QTDISP) or as the coefficient of variation of all QT inter vals (QTCV). Results. During the 25-month follow-up period (mean time on waiting list, 201 days), the mortality rate was 27%/year, divided e qually between heart failure and sudden deaths, No clinical variable i dentified at entry predicted mortality, QTDISP and QTCV were strong mo rtality predictors, with a 4.1-fold increase in mortality in patients with QTDISP > 140 ms compared with those patients with QTDISP less tha n or equal to 140 ms (95% CI 1.1 to 14.9), whereas a QTCV greater than or equal to 9% also predicted a 4.1-fold increased risk of death (95% CI 1.4 to 11.8). Although 88% of all SAECGs were abnormal, no patient with a normal SAECG died suddenly during the waiting period. Conclusi ons. Indexes of QT dispersion provide a means of stratifying a patient 's risk of dying while awaiting heart transplantation and may help to establish priority on a heart transplant waiting list. (C) 1997 by the American College of Cardiology.