The diastolic pressure time index (DPT-Index) was a successful hemodynamic parameter in distinguishing between relevant and non-relevant aortic regurgitation (AR), as well as predicting 1-year mortality, in patients treated with transcatheter aortic valve implantation (TAVI).
For patients with severe symptomatic aortic stenosis (AS) who are at high risk for surgery, TAVI has become an accepted standard of care. After TAVI, however, AR continues to be problematic, in both self-expanding and balloon-expandable prostheses. AR incidence ranges from 48% to 93%, with up to 21% of cases resulting in moderate to severe AR. The more severe cases are independently associated with increased in-hospital and mid-term mortality.
In this study, researchers collected data from 362 patients who underwent transfemoral TAVI with either the CoreValve (Medtronic Inc; Minneapolis, MN) or SAPIEN device (Edwards Lifesciences; Irvine, CA) for symptomatic aortic valve stenosis.
AR was assessed by standardized aortic-root angiography and graded on a scale of 0 to 4 (0=no AR, 1=mild, 2=moderate, 3=moderately severe, and 4=severe).
The DPT-Index was calculated at the earliest 5 minutes after device deployment: left ventricular and aortic pressures were simultaneously determined after TAVI and the area between the aortic and left ventricular pressure-time curves (DP-Area) was measured during diastole. The DP-Area was divided by duration of diastole and adjusted for the scaling of the pressure-time curve to calculate the DPT-Index. The DPT-Index was then adjusted for the respective systolic blood pressure of the patient.
Of the 362 patients, 204 (56%) were treated with the CoreValve prosthesis and 158 with the SAPIEN prosthesis. AR was found in 258 (71.3%) patients and graded mild in 222 (61.3%) and moderate in 36 (9.9%). No AR above grade 2 was present, and 104 patients did not have evidence of AR during the aortic-root angiography.
“The DPT-Indexadj showed a stepwise decrease with increasing AR determined by aortic-root angiography,” researchers noted.
The DPT-Indexadj was 31.5 ± 7.5 in patients without angiographic evidence of AR, 30.4 ± 6.4 in patients with mild AR, and 26.2 ± 5.8 in patients with moderate AR. The patients with angiographically “non-relevant” AR (grade <2) had a significantly higher DPT-Indexadj (30.7 ± 6.8) compared to those patients with “relevant” AR (grade ≥2; DPT-Indexadj=26.2 ± 5.8; P<.001).
During the first year after TAVI, 88 (24.3%) patients died. The DPT-Indexadj was significantly higher in those patients who survived compared to those who died (31.3 ± 6.5 vs 27.3 ± 6.8; P<.001). In addition, patients with a DPT-Indexadj ≤27.9 had a significantly higher 1-year mortality risk compared to patients with a DPT-Indexadj >27.9 (41.4% vs 13.5%; hazard ratio [HR]: 3.8; 95% confidence interval [CI]: 2.4-5.9; P log rank-test <.001).
However, in a multivariable Cox-regression analysis, only the Society for Thoracic Surgery Score (increase per 5%) and a DPT-Indexadj ≤27.9 independently predicted 1-year mortality (HR: 2.5; 95% CI: 1.8-3.7; P<.001).
“Despite the recently published VARC-2 [Valve Academic Research Consortium-2] recommendations, the precise quantification of AR remains controversial, especially during the procedure,” researchers wrote. “Although widely used, it [angiographic evaluation of AR] is a subjective and investigator-dependent parameter and strongly affected by the position of the pigtail catheter, amount of contrast agent, injection rate, and systemic blood pressure. In our analysis, the angiographic findings could not predict the outcome of patients with AR after TAVI. It seems that aortic-root angiography in this setting provides limited prognostic information unless in severe AR.”
“Further studies are necessary to investigate the efficacy of an intraprocedural decision making guided by hemodynamic parameters, especially the DPT-Indexadj,” researchers concluded.
Höllriegel R, Woitek F, Stativa R, et al. Hemodynamic assessment of aortic regurgitation after transcatheter aortic valve implantation: the diastolic pressure time index. JACC Cardiovasc Interv. 2016. doi:10.1016/j.jcin.2016.02.012.