Absolute Survival After CRT According to Baseline QRS
Background In the major trials of cardiac resynchronization therapy (CRT), the survival benefit of the therapy, relative to control subjects, increases with QRS duration. In the non-CRT heart failure population, however, a wide QRS duration is associated with a shorter survival. Relative survival benefit from a therapy, however, is not synonymous with a longer absolute survival. We sought to determine whether baseline QRS duration relates to the absolute survival after CRT.
Methods and Results In this prospective, longitudinal, observational study, 3,319 consecutive patients undergoing CRT (QRS 120–149 ms 26%, QRS 150–199 ms 58%, and QRS ≥200 ms 16%) were assessed in relation to mortality over 10 years. Overall mortality rates (per 100 patient-years) were 9.2%, 9.3%, and 13.3% in the 3 groups, respectively (all P < .001). Cardiac mortality rates were 6.2, 6.0, and 9.9 per 100 patient-years, respectively (all P < .001). Compared with the QRS 120–149 ms group, cardiac mortality was highest in the QRS ≥200 ms group (hazard ratio [HR] 1.72 [95% CI 1.35–2.19], P < .001), independent of age, gender, New York Heart Association class, presence of atrial fibrillation, heart failure etiology, and left ventricular ejection fraction. Median survival after CRT was longest in patients with a width of QRS 120–149 ms and shortest in patients with a QRS ≥200 ms (P < .001). In multivariable analyses, a QRS ≥200 ms emerged as a powerful independent predictor of both overall (HR 1.44 [95% CI 1.07–1.94], P = .017) and cardiac mortality (HR 1.59 [95% CI 1.14–2.24], P = .007).
Conclusions At long-term follow-up, absolute overall and cardiac survival after CRT is similar in patients with a preimplant QRS duration of 120 to 149 ms and 150 to 199 ms but markedly shorter in patients with a QRS ≥200 ms.
Cardiac resynchronization therapy (CRT) has revolutionized the management of patients with heart failure (HF), severe left ventricular (LV) systolic dysfunction, and a prolonged QRS duration. Several randomized controlled trials have shown that CRT prolongs survival; reduces HF hospitalizations; and improves symptoms, exercise capacity, and quality of life. In quantifying the effects of CRT on survival, trials have generally focused on relative rather than absolute survival. A patient who derives a benefit from CRT relative to a control subject may, nevertheless, have a short absolute survival after CRT. Conversely, a patient may have a long absolute survival after CRT but gain only partially from CRT when compared with control subjects. Both relative and absolute survival would be important in clinical decision making.
Despite intensive search for predictors of outcome after CRT, QRS duration remains the simplest and most robust measure. The landmark trials of CRT have adopted a QRS ≥120 ms as the cutoff for electrical dyssynchrony, and hence, this criterion has been adopted by guidelines for CRT. In a meta-analysis of randomized controlled trials, Sipahi et al showed that CRT is most effective in patients with a QRS ≥150 ms. A recent subanalysis of the REVERSE study showed a linear reduction in LV volumes after CRT with QRS durations between 120 and 180 ms, followed by a plateau in efficacy in wider QRS complexes. Based on such findings, current CRT guidelines consider that the best candidates for CRT are patients with a QRS ≥150 ms, whereas the evidence for CRT patients with a QRS 120–150 ms is regarded as weaker.
Although a wide QRS duration has been shown to predict a relative benefit in survival after CRT, we should consider that it may also influence absolute survival. In the present MULIN CRT study, we explore the absolute survival after CRT among patients with a wide range of QRS durations, including patients with a QR ≥200 ms.
Abstract and Introduction
Abstract
Background In the major trials of cardiac resynchronization therapy (CRT), the survival benefit of the therapy, relative to control subjects, increases with QRS duration. In the non-CRT heart failure population, however, a wide QRS duration is associated with a shorter survival. Relative survival benefit from a therapy, however, is not synonymous with a longer absolute survival. We sought to determine whether baseline QRS duration relates to the absolute survival after CRT.
Methods and Results In this prospective, longitudinal, observational study, 3,319 consecutive patients undergoing CRT (QRS 120–149 ms 26%, QRS 150–199 ms 58%, and QRS ≥200 ms 16%) were assessed in relation to mortality over 10 years. Overall mortality rates (per 100 patient-years) were 9.2%, 9.3%, and 13.3% in the 3 groups, respectively (all P < .001). Cardiac mortality rates were 6.2, 6.0, and 9.9 per 100 patient-years, respectively (all P < .001). Compared with the QRS 120–149 ms group, cardiac mortality was highest in the QRS ≥200 ms group (hazard ratio [HR] 1.72 [95% CI 1.35–2.19], P < .001), independent of age, gender, New York Heart Association class, presence of atrial fibrillation, heart failure etiology, and left ventricular ejection fraction. Median survival after CRT was longest in patients with a width of QRS 120–149 ms and shortest in patients with a QRS ≥200 ms (P < .001). In multivariable analyses, a QRS ≥200 ms emerged as a powerful independent predictor of both overall (HR 1.44 [95% CI 1.07–1.94], P = .017) and cardiac mortality (HR 1.59 [95% CI 1.14–2.24], P = .007).
Conclusions At long-term follow-up, absolute overall and cardiac survival after CRT is similar in patients with a preimplant QRS duration of 120 to 149 ms and 150 to 199 ms but markedly shorter in patients with a QRS ≥200 ms.
Introduction
Cardiac resynchronization therapy (CRT) has revolutionized the management of patients with heart failure (HF), severe left ventricular (LV) systolic dysfunction, and a prolonged QRS duration. Several randomized controlled trials have shown that CRT prolongs survival; reduces HF hospitalizations; and improves symptoms, exercise capacity, and quality of life. In quantifying the effects of CRT on survival, trials have generally focused on relative rather than absolute survival. A patient who derives a benefit from CRT relative to a control subject may, nevertheless, have a short absolute survival after CRT. Conversely, a patient may have a long absolute survival after CRT but gain only partially from CRT when compared with control subjects. Both relative and absolute survival would be important in clinical decision making.
Despite intensive search for predictors of outcome after CRT, QRS duration remains the simplest and most robust measure. The landmark trials of CRT have adopted a QRS ≥120 ms as the cutoff for electrical dyssynchrony, and hence, this criterion has been adopted by guidelines for CRT. In a meta-analysis of randomized controlled trials, Sipahi et al showed that CRT is most effective in patients with a QRS ≥150 ms. A recent subanalysis of the REVERSE study showed a linear reduction in LV volumes after CRT with QRS durations between 120 and 180 ms, followed by a plateau in efficacy in wider QRS complexes. Based on such findings, current CRT guidelines consider that the best candidates for CRT are patients with a QRS ≥150 ms, whereas the evidence for CRT patients with a QRS 120–150 ms is regarded as weaker.
Although a wide QRS duration has been shown to predict a relative benefit in survival after CRT, we should consider that it may also influence absolute survival. In the present MULIN CRT study, we explore the absolute survival after CRT among patients with a wide range of QRS durations, including patients with a QR ≥200 ms.
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