Postextrasystolic potentiation of systolic gradient in valvular aortic stenosis: clinical usefulness and analysis of hemodynamic factors

Characteristics and usefulness of unintended premature ventricular contraction during invasive assessment of aortic stenosis

BACKGROUND

Postextrasystolic potentiation (PESP)-associated augmentation in left ventricular-aorta pressure gradient (LVAoG) observed after incidental premature ventricular contraction (PVC) during resting echocardiography is similar to dobutamine stress echocardiography (DSE)-associated augmentation in LVAoG in patients with low-flow, low-gradient (LF-LG) aortic stenosis (AS). What is not known is whether a similar relationship exists when unintended PVC causes PESP during cardiac catheterization in patients with AS.

METHODS

We retrospectively reviewed all catheterizations performed for patients with at least moderate AS who had LVAoG assessment. Univariate and multivariate analyses were conducted to determine the predictors of pre- and post-PVC mean LVAoG ≥ 40 mmHg.

RESULTS

Between September 2015 to September 2017, of 140 individuals undergoing cardiac catheterization, 34 met study criteria. Mean pre-PVC gradient was 38.9 ± 22.8 mmHg. All patients exhibited PESP-associated augmentation of LVAoG by an average of 28 ± 12%. In multivariate analysis, the only significant predictor of post-PVC mean LVAoG ≥ 40 mmHg was preserved LV function (OR 6.81; 95% CI 1.41-32.82, p = 0.02). Inability to generate ≥ 40 mmHg of mean LVAoG post-PVC had 100% specificity for nonsevere AS in our observational cohort.

CONCLUSIONS

Unintended but interpretable PVCs occurred in one in four patients with AS undergoing cardiac catheterization with measurable hemodynamics. All of our patients with PVCs, regardless of underlying LVEF, exhibited PESP-associated augmentation of LVAoG. Our exploratory analysis suggests that inability to generate ≥40 mmHg of mean LVAoG post-PVC is highly specific for nonsevere AS.

Age-related decline in postextrasystolic potentiation in patients with aortic stenosis

In aortic stenosis (AS), postextrasystolic potentiation (PESP), a measure of contractile reserve, has been demonstrated by an increased aortic valve gradient (AVG) after a ventricular extrasystole (VE). We studied age-related changes in PESP in 20 consecutive patients (age, 65-89 years) with significant AS (aortic area <or= 1.0 cm(2)) on cardiac catheterization with VE on AVG pressure recording. Hemodynamics and LV systolic time intervals were averaged from three consecutive beats and from the post-VE beat. Changes (Delta) in AVG, pre-ejection period/LV ejection time ratio (PEP/LVET), aortic diastolic pressures (AoDP), and LV end-diastolic pressures (LVEDP) were calculated. Age was inversely correlated with DeltaAVG (r = -0.84, P = 0.0001), with DeltaPEP/LVET (r = -0.87, P = 0.0001), and with DeltaAoDP (r = -0.89, P = 0.0001), but not with DeltaLVEDP (r = 0.23, P = 0.31). On multivariate analysis, only age was associated with DeltaAVG (r(2) = 0.72, P = 0.0001). There was an age-related decline in PESP in patients with AS, which was accompanied by changes in contractile reserve and afterload reduction, but independent of preload reserve.

Postextrasystolic potentiation. Do we really know what it means and how to use it?

Postextrasystolic potentiation (PESP), the increase in contractility that follows an extrasystole, is an interesting phenomenon that has been known for almost 100 years. The literature on this effect is reviewed. It is found that there is significant evidence that the phenomenon is independent of muscle loading and represents a distinct property of the myocardium. Examination of the literature pertaining to the cause of the effect suggests that calcium shifts within the sarcoplasmic reticulum are responsible, although there are some conflicts with this conclusion. Regarding the utility of PESP as a diagnostic test of latent viability of ischemic myocardium, the literature review reveals contradictions and conflicts with several methodological problems of the experiments. Finally, concerning the utility of continuous PESP (paired-pacing) to augment ventricular function in the failing ventricle, the studies again are inconclusive and methodologically suspect. Conditions for the proper analysis of the PESP response are reported, and suggestions for future studies are introduced.

Differences of postextrasystolic behavior of left ventricular and aortic pressures between fixed and dynamic left ventricular outflow tract stenosis

The dynamic behavior of fixed LV outflow tract stenosis partly resembles that of OCM. To analyze their differences we studied basal and postextrasystolic (post-PVC) peak-to-peak LV aortic gradients, aortic systolic pressure, and pulse pressure in 14 OCM and in 36 pure VAS without two-dimensional echocardiographic findings of OCM. Fifteen mild VAS had basal gradients similar to those of OCM (39 +/- 17 mm Hg vs 24 +/- 16 mm Hg). Patients with OCM show a post-PVC gradient (109 +/- 41 mm Hg) similar to that of VAS (110 +/- 50 mm Hg). However, the latter were departing from much higher gradients (VAS 72 +/- 30 mm Hg vs OCM 24 +/- 16 mm Hg). Decrement of post-PVC aortic systolic pressure and pulse pressure were frequent in both groups, but decrement of pulse pressure greater than 5 mm Hg were more frequent in OCM. We concluded that (1) post-PVC increased aortic gradients and decreased aortic systolic pressure occurred in both VAS and OCM; (2) post-PVC decreased aortic pulse pressure might occur in VAS; and (3) association of post-PVC gradient increment greater than 75 percent and pulse pressure decrement greater than 5 mm Hg are strongly suggestive of OCM.