Table 6 Prior Studies That Evaluated the Effect of Increased Heart Rate on Optimal Atrioventricular Delay in Patients with CRT

Melzer et al

20

CRTresponder 64 ± 10 yrs, NYHA < 3. VDD and DDD mode used. EF 23.2 ± 7.6

22.5 ± 9.6 bpm above baseline Supine bicycle ergometer beginning with 25 W and increasing the workload by 25 W every 2 min. (71+9 W).

Supine bicycle exercise

Combination of mitral inflow PW Doppler, trans-esophagel left atrial electrograms and surface ECG.

No AV delay change needed in VDD mode. With DDD mode, optimal AV delay was shortened by 2.6 ms/10 bpm

Scharf et al

36

Biv-ICD, 62 ± 8 yrs, EF 17 ± 5

Pacing heart rate increased to 110-120 bpm and with exercise increase in intrinsic heart rate at least 20 bpm above baseline. Optimal AV Delay determined post exercise

DDD pacing or treadmill exercise In 22 patients with DDD HR increased to 110-120 bpm. In 14 patients with exercise HR increased at least 20 bpm above baseline

LVOT VTI post exercise

Prolongation of AV delay found optimal at increased HRs. An increase in LVOT VTI of 0.047 cm/s per 20 ms prolongation of AV delay per 10 bpm increase in heart rate for DDD pacing and 0.146 cm/s increase in VTI per 20 ms prolongation of AV delay per 10 bpm increase in heart rate during exercise. Beneficial effect of AV delay prolonging was observed until heart rate 110 bpm.

Grimm R et al

15

CRT patients without atrial pacing who were able to exercise, 57 ± 16 yrs, EF 37 ± 15

Atrial-sensed Biv pacing, HR 20-40 bpm above baseline

Supine bicycle exercise

Maximum LV filling time. The duration of LV filling, stroke volume, and a clinical assessment of LV function were studied.

AV delay shortening needed at increased HR for all patients using three independent criteria. Consistent trends were observed between all three parameters for 12 out of the 15 patients.

Mokrani B et al

50

CRT patients who were able to exercise, 69 ± 7 yrs, EF 25 ± 7

Atrial-sensed Biv pacing, 60% of the maximal predicted. HR, with the sensed AV delay set at 40, 70, 100, 120, 150, and 200 ms. Only 1 maximum HR tested.

Supine bicycle exercise

LVOT VTI, LV filling time

Optimal AV delay based on LVOT-VTI was shorter during exercise than at rest in 37%, unchanged in 37%, and longer in 26% of patients. The optimal AV delay based on mitral inflow filling time was shorter during exercise than at rest in 27%, unchanged in 23%, and longer in 50% of patients. Opt-imization of AV delay during exercise inc-reased LV filling time and LVOT-VTI (P < .05)

Valzania C et al

24

CRT patients able to exercise, 63 ± 9 yrs, EF 36 ± 9

Atrial-sensed Biv pacing, 20-beat increase in HR above baseline. Only 1 maximum HR tested.

Supine bicycle exercise

LVOT VTI by PW Doppler and automated intra-cardiac electrogram (IEGM)to optimize AV delay and VV delay

Optimal VV delay varied considerably from rest to exercise, while AV delay did not change. A substantial agreement in deriving optimized AV delays was observed between the echocardiogram and the IEGM method, both at rest and during exercise.

Whinnett ZI et al

20

CRT patients who were able to exercise, 68 yrs(46-82 yrs)

Atrial-sensed Biv pacing, HR of 100 bpm with exercise. Pacing at rest at 5 bpm above resting rate and at 100 bpm. Sensed-paced difference, calculated as an "expected" value for the exercise optimum.

Treadmill exercise

Noninvasive finger arterial pressure measurements using a Finometer

Hemodynamic optimization of AV delay under three different conditions before exercise. The resting three-phase model correlated well with the actual exercise optimal AV delay (r = 0.85, mean difference ± standard [SD] = 3.7 ± 17 ms). In 11 patients, the optimal AV delay was shorter during exercise than at rest, in eight patients it was longer and in 1 patient, unchanged.

Tse Hung-Fat et al

20

CRT patients who were able to exercise, 65 ± 4 yrs, EF 27 ± 3

AV delay adaptive algorithm, maximum programmed equal to the optimal resting AV delay during atrial pacing and the minimum

AV delay to the optimal resting AV delay during atrial pacing--50 bpm in 10-ms decrements.

Cardiopulmonary treadmill exercise

Longest LV filling time without truncation of the A wave from mitral inflow PW Doppler

In heart failure patients with severe chronotropic incompetence as defined by failure to achieve < 70% target HR, appropriate use of rate-adaptive pacing with CRT provides incremental benefit on exercise capacity during exercise.