The atrioventricular delay of cardiac resynchronization can be optimized hemodynamically during exercise and predicted from resting measurements.

BACKGROUND: Atrioventricular (AV) optimization of cardiac resynchronization therapy (CRT) is typically calculated at rest. However, patients often become symptomatic during exercise. OBJECTIVE: In this study, we use acute noninvasive hemodynamics to optimize the AV delay of CRT during exercise and investigate whether this exercise optimum can be predicted from a three-phase resting model. METHODS: In 20 patients with CRT, we adjusted the sensed AV delay while the patient exercised on a treadmill up to a heart rate of 100 bpm to identify the hemodynamically optimal value. Separately, at rest, by pacing with three different configurations and calculating the sensed-paced difference, we calculated an "expected" value for the exercise optimum. RESULTS: It was possible to perform AV delay optimization while a patient exercised. The resting three-phase model correlated well with the actual exercise optimal AV delay (r = 0.85, mean difference +/- standard deviation [SD] = 3.7 +/- 17 ms). Simply using measurements made at rest during atrial-sensed pacing showed a poorer correlation with exercise (r = 0.64, mean difference +/- SD = 2.2 +/- 24 ms). The three-phase resting model allows improved exercise hemodynamics to be achieved. Programming according to the three-phase resting model yields an exercise blood pressure of only 0.5 mmHg (+/-1.4 mmHg; P = NS) less than the true exercise optimum, whereas programming the resting sensed optimum yields an exercise blood pressure of 1.4 mmHg (+/-2.2 mmHg, P = .02) less than the true optimum. CONCLUSIONS: Using acute noninvasive hemodynamics and a protocol of alternations, it is possible to optimize the AV delay of cardiac resynchronization devices even while a patient exercises. In clinical practice, the exercise optimum AV delay could be determined from three phases of resting measurements, without performing exercise.

Limitations of the New York Heart Association functional classification system and self-reported walking distances in chronic heart failure.

BACKGROUND: Two ways to evaluate the symptoms of heart failure are the New York Heart Association (NYHA) classification and asking patients how far they can walk (walk distance). The NYHA system is commonly used, although it is not clear how individual clinicians apply it. AIM: To investigate how useful these measures are to assess heart failure and whether other questions might be more helpful. METHODS: 30 cardiologists were asked what questions they used when assessing patients with heart failure. To assess interoperator variability, two cardiologists assessed a series of 50 patients in classes II and III using the NYHA classification. 45 patients who had undergone cardiopulmonary testing were interviewed using a specially formulated questionnaire. They were also asked how far they could walk before being stopped by symptoms, and then tested on their ability to estimate distance. RESULTS: The survey of cardiologists showed no consistent method for assessing NYHA class and a literature survey showed that 99% of research papers do not reference or describe their methods for assigning NYHA classes. The interoperator variability study showed only 54% concordance between the two cardiologists. 70% of cardiologists asked patients for their walk distance; however, this walk distance correlated poorly with actual exercise capacity measured by cardiopulmonary testing (rho = 0.04, p = 0.82). CONCLUSION: No consistent method of assessing NYHA class is in use and the interoperator study on class II and class III patients gave a result little better than chance. Some potential questions are offered for use in assessment. Walking distance, although frequently asked, does not correlate with formally measured exercise capacity, even after correction for patient perception of distance, and has never been found to have prognostic relevance. Its value is therefore doubtful.