Preoperative left ventricular wall stress, ejection fraction, and aortic valve gradient as prognostic indicators in aortic valve stenosis

Meta-Analysis of Outcomes of Transcatheter Aortic Valve Implantation Among Patients With Low Gradient Severe Aortic Stenosis

Transcatheter aortic valve implantation (TAVI) has emerged as an effective therapy for patients with severe aortic stenosis (AS). However, data on TAVI outcomes in patients with low gradient (LG) AS are limited. We performed a meta-analysis of studies comparing TAVI outcomes between patients with classic high gradient (HG) and LG AS through November 2018. The 30-day mortality, mid-term all-cause, and cardiovascular mortality at maximum follow-up were compared between patients with HG and LG AS (Pairwise meta-analysis), and between the three distinct groups of AS including HG, paradoxical low-flow low-gradient and low gradient with reduced ejection fraction (rEF-LG) (Network meta-analysis). Nineteen studies (n = 27,204 patients) met the inclusion criteria. The HG group had less 30-day, mid-term all-cause and cardiovascular mortality compared with the low-gradient AS group overall, (6% vs 7.5%, OR 0.76, 95% CI 0.66 to 0.87, I² = 18%), (21% vs 29%, OR 0.59, 95% CI 0.52 to 0.67, I² = 62%), and (12.6% vs 18.7%, OR 0.61, 95% CI 0.49 to 0.76, I² = 62%), respectively, p <0.0001. These outcomes were confirmed in a trial sequential analysis in which the cumulative Z-curve crossed the conventional test boundary as well as the trial sequential monitoring boundary for all outcomes. The network meta-analysis revealed that patients with rEF-LG had similar outcomes to those with pLFLG, and both had worse outcomes than patients with classic HG AS. In conclusion patients with classic HG have better 30-day mortality, mid-term all-cause and cardiovascular mortality compared with LG patients following TAVI. Among patients with LG severe AS, TAVI outcomes were similar in patients with rEF-LG and pLFLG.

Impact of myocardial fibrosis in patients with symptomatic severe aortic stenosis

BACKGROUND

In this prospective follow-up study, the effect of myocardial fibrosis on myocardial performance in symptomatic severe aortic stenosis was investigated, and the impact of fibrosis on clinical outcome after aortic valve replacement (AVR) was estimated.

METHODS AND RESULTS

Fifty-eight consecutive patients with isolated symptomatic severe aortic stenosis underwent extensive baseline characterization before AVR. Standard and tissue Doppler echocardiography and cardiac magnetic resonance imaging (late-enhancement imaging for replacement fibrosis) were performed at baseline and 9 months after AVR. Endomyocardial biopsies were obtained intraoperatively to determine the degree of myocardial fibrosis. Patients were analyzed according to the severity of interstitial fibrosis in cardiac biopsies (severe, n=21; mild, n=15; none, n=22). The extent of histologically determined cardiac fibrosis at baseline correlated closely with New York Heart Association functional class and markers of longitudinal systolic function (all P<0.001) but not global ejection fraction or aortic valve area. Nine months after AVR, the degree of late enhancement remained unchanged, implying that AVR failed to reduce the degree of replacement fibrosis. Patients with no fibrosis experienced a marked improvement in New York Heart Association class from 2.8+/-0.4 to 1.4+/-0.5 (P<0.001). Only parameters of longitudinal systolic function predicted this functional improvement. Four patients with severe fibrosis died during follow-up, but no patient from the other groups died.

CONCLUSIONS

Myocardial fibrosis is an important morphological substrate of postoperative clinical outcome in patients with severe aortic stenosis and was not reversible after AVR over the 9 months of follow-up examined in this study. Because markers of longitudinal systolic function appear to indicate sensitively both the severity of myocardial fibrosis and the clinical outcome, they may prove valuable for preoperative risk assessment in patients with aortic stenosis.

Risk Factors for Postoperative Heart Failure in Patients Operated on for Aortic Stenosis

BACKGROUND

Risk factors for postoperative heart failure (PHF) have not been specifically studied in valve surgery although it has been acknowledged that patient variables may have a more profound influence on postoperative outcome than valve-related factors.

METHODS

All patients undergoing isolated aortic valve replacement for aortic stenosis from January 1995 to December 2000 in the southeast region of Sweden were studied (n = 398). Forty-five patients with aortic valve replacement required treatment for PHF. Univariate and multivariate logistic regression analysis was carried out to identify risk factors for PHF.

RESULTS

Thirty-day mortality was 6.7% versus 1.4% for patients with and without PHF, respectively (p = 0.05). With regard to clinical presentation of aortic stenosis, angina was associated with reduced risk, whereas history of congestive heart failure increased the risk for PHF. Five preoperative (hypertension, history of congestive heart failure, severe systolic left ventricular dysfunction, pulmonary hypertension, preoperative hemodynamic instability) and two intraoperative (aortic cross-clamp time, intraoperative myocardial infarction) variables were identified as independent risk factors for PHF. Patient-prosthesis mismatch did not influence the risk of PHF significantly.

CONCLUSIONS

Postoperative heart failure was associated with a marked increase in postoperative mortality and morbidity. Risk factors for PHF were variables indicating preexisting myocardial dysfunction, increased right or left ventricular afterload, and intraoperative myocardial injury. Our results highlight issues concerning cross-clamp time and myocardial protection, particularly for patients with preoperatively compromised myocardial function. Asymptomatic patients with significant aortic stenosis should be considered for surgery before substantial echocardiographic evidence of left ventricular dysfunction or increased pulmonary artery pressure develops.

Myocardial function in severe aortic stenosis before and after aortic valve replacement: A Doppler tissue imaging study

BACKGROUND

The aim of the study was to assess the value of Pulsed-wave Doppler tissue imaging (DTI) in assessing diastolic and systolic function in patients with severe aortic value stenosis.

METHODS

Thirty-five patients with aortic stenosis (AS) (valve orifice < or = 1 cm 2 , mean age 71.8 +/- 6.2) and 35 comparable healthy subjects were studied. All subjects performed conventional 2-dimensional Doppler echocardiography and DTI at mitral annulus level. Patients with AS were divided into 2 groups: 16 patients who presented initial signs of HF and a depressed left ventricular systolic function (AS I) (EF: 35%-50%) and 19 patients were asymptomatic and had normal left ventricular systolic function (EF > 50%) (ASII). The 16 symptomatic AS patients underwent surgical aortic valve replacement and were examined after 1 year.

RESULTS

DTI was able to detect abnormalities of systolic and diastolic function in AS: the significantly lower peak S velocity in AS I than in AS II and in controls, both at septum and lateral wall level; the significantly lower peak E velocity in AS I than in AS II and in controls both at septum and lateral wall level; the significantly higher peak A velocity in AS I than in AS II and in controls both at septum and lateral wall level; the significant lower E/A ratio in AS I than in AS II and in controls both at septum and lateral wall level.

CONCLUSION

We found a significant inverse correlation between DTI lateral S velocity, DTI peak E velocity, lateral DTI E/A ratio, and AS peak and mean gradient. According to the results of this study we can affirm that DTI parameters surely had an important physiopathological impact in the knowledge of myocardial function in patients with severe aortic stenosis.

Severe Aortic Stenosis and Myocardial Function

Background— The aim of this study was to assess the myocardial reflectivity pattern in severe aortic valve stenosis through the use of integrated backscatter (IBS) analysis. Patients with aortic stenosis (AS) were carefully selected in the Department of Cardiology.

Methods and Results— Thirty-five subjects (AS: valve orifice ≤1 cm 2 ; 12 female; mean age, 71.8±6.2 years) and 25 healthy subjects were studied. All subjects of the study had conventional 2D-Doppler echocardiography and IBS. Backscatter signal was sampled at the septum and posterior wall levels. Patients with AS were divided into 2 groups: 16 patients with initial signs of congestive heart failure and a depressed left ventricular systolic function (DSF) (ejection fraction [EF] range, 35% to 50%) and 19 asymptomatic patients with normal left ventricular systolic function (NSF) (EF >50%). Myocardial echo intensity (pericardium related) was significantly higher at the septum and posterior wall levels in DSF than in NSF and in control subjects. IBS variation, as an expression of variation of the signal, appeared to be significantly lower in AS with DSF than in NSF and in control subjects, at both the septum and posterior wall levels. Patients with DSF underwent aortic valve replacement, and, during surgical intervention, a septal myocardial biopsy was made for evaluation of myocardium/fibrosis ratio. Abnormally increased echo intensity was detected in left ventricular pressure overload by severe aortic stenosis and correlated with increase of myocardial collagen content (operating biopsy).

Conclusions— One year after aortic valve replacement, we observed a significant reduction of left ventricular mass, and, only if pericardial indexed IBS value (reduction of interstitial fibrosis) decreased, it was possible to observe an improvement of EF and of IBS variation.

Clinical efficacy of Doppler-echocardiographic indices of aortic valve stenosis: a comparative test-based analysis of outcome

OBJECTIVES

This study was designed to assess which hemodynamic index best accounts for clinical severity of aortic stenosis (AS) and to analyze the value of low-dose dobutamine testing.

BACKGROUND

Pressure gradient and valve area are suboptimal because they depend on flow rate, correlate poorly with symptoms, and provide limited prognostic information. Recently, new indices and low-dose inotropic stimulation have been introduced, but their clinical value remains uncertain.

METHODS

A total of 307 consecutive patients with AS were included in an ambispective study design (71 +/- 12 years old; peak jet velocity: 3.7 +/- 1.1 m/s). Clinical and Doppler-echocardiographic data were obtained, as well as results of low-dose dobutamine infusion (47 patients). Using receiver-operator-characteristic curve analysis, we evaluated jet velocity, pressure gradient, valve area, resistance, stroke-work loss (SWL), and dobutamine-induced increase in area for predicting 1) symptomatic status at entry, 2) early (</=3 months) cardiovascular death or aortic valve replacement, and 3) long-term outcome. Logistic regression and Cox models were designed multivariate and adjusted by bootstrapping.

RESULTS

Only 28% of patients were alive without valve replacement at the end of the follow-up period (22 +/- 4 months). The decision for valve replacement was made by the referring physician, blinded to the SWL, valve resistance, and dobutamine results. Non-flow-corrected indices performed better than valve area and valve resistance. Among them, SWL best predicted the defined end points. Odds/hazard ratios associated with a SWL Delta = 17% were 5.14 for presenting AS symptoms, 4.68 for early events, and 2.31 for late outcome. A cutoff value of SWL >25% best discriminated clinical end points. Other independent predictors of prognosis were symptomatic status and left ventricular ejection fraction. Dobutamine testing added no value to baseline models.

CONCLUSIONS

Non-flow-corrected indices show the highest clinical efficacy in aortic stenosis. Among these, SWL best predicts symptomatic status and outcome and therefore should be incorporated to aid patient management in unclear situations.

Survival after aortic valve replacement for severe aortic stenosis with low transvalvular gradients and severe left ventricular dysfunction

OBJECTIVE

We sought to assess whether aortic valve replacement (AVR) among patients with severe aortic stenosis (AS), severe left ventricular (LV) dysfunction and a low transvalvular gradient (TVG) is associated with improved survival.

BACKGROUND

The optimal management of patients with severe AS with severe LV dysfunction and a low TVG remains controversial.

METHODS

Between 1990 and 1998, we evaluated 68 patients who underwent AVR at our institution (AVR group) and 89 patients who did not undergo AVR (control group), with an aortic valve area < or = 0.75 cm(2), LV ejection fraction < or = 35% and mean gradient < or = 30 mm Hg. Using propensity analysis, survival was compared between a cohort of 39 patients in the AVR group and 56 patients in the control group.

RESULTS

Despite well-matched baseline characteristics among propensity-matched patients, the one- and four-year survival rates were markedly improved in patients in the AVR group (82% and 78%), as compared with patients in the control group (41% and 15%; p < 0.0001). By multivariable analysis, the main predictor of improved survival was AVR (adjusted risk ratio 0.19, 95% confidence interval 0.09 to 0.39; p < 0.0001). The only other predictors of mortality were age and the serum creatinine level.

CONCLUSIONS

Among select patients with severe AS, severe LV dysfunction and a low TVG, AVR was associated with significantly improved survival.

Dobutamine echocardiography in patients with aortic stenosis and left ventricular dysfunction: predicting outcome as a function of management strategy

STUDY OBJECTIVE

To prospectively address the question whether the assessment of valvular hemodynamics and myocardial function during low-dose dobutamine infusion can guide decision making in patients with aortic stenosis and left ventricular (LV) dysfunction.

PATIENTS AND MEASUREMENTS

Twenty-four patients with aortic stenosis and LV dysfunction (mean ejection fraction, 28%; New York Heart Association class, II to IV) were studied by dobutamine echocardiography assessing mean pressure gradient, aortic valve area, and aortic valve resistance. Patients were prospectively divided into severe and nonsevere aortic stenosis groups according to the response of the valve area to the augmentation of systolic flow. The clinical decision was considered to be concordant with the results of dobutamine echocardiography, when patients with severe aortic stenosis and preserved contractile function were referred by a specialist for aortic valve replacement and when patients with nonsevere aortic stenosis were not. Patients were observed for up to 3 years.

RESULTS

All eight patients with severe aortic stenosis who were referred for surgery survived and had good cardiovascular outcomes, and six of eight patients who were not initially referred for surgery had poor outcomes, including heart failure and sudden cardiac death. The eight patients with nonsevere aortic stenosis did comparatively well without valve replacement. Cardiac death or pulmonary edema occurred in 4 of 16 patients (25%) when the clinical decision was concordant with the results of the dobutamine echocardiogram and occurred in 6 of 8 patients (75%) when the clinical decision was discordant (p = 0.019 [chi(2) test]).

CONCLUSION

Patients with aortic stenosis, LV dysfunction, and relatively low gradients have better outcomes when management decisions are based on the results of dobutamine echocardiograms. Those patients identified as having severe aortic stenosis and preserved contractile reserve by dobutamine echocardiography should undergo surgery, while patients identified as having nonsevere aortic stenosis can be managed conservatively.

Echocardiographic prediction of clinical outcome in medically treated patients with aortic stenosis

BACKGROUND

The onset of symptoms is crucial in the natural history of severe aortic stenosis. In contrast, the impact of the degree of valve obstruction and left ventricular dysfunction on clinical outcome in terms of progression of symptoms and mortality is undefined.

METHODS AND RESULTS

Between April 1989 and June 1996, 108 patients (75% male, aged 68.7 +/- 10.3 years) with pure and isolated aortic stenosis of at least moderate degree had a complete Doppler echocardiography. Left ventricular end-diastolic and end-systolic diameters, thickness of ventricular septum, mass and ejection fraction, and maximal instantaneous aortic gradient were measured. Patients were followed up through March 1999. Sixty-five patients who underwent aortic valve replacement were censored at the time of surgery. The end point was considered to be death or symptomatic progression (onset of new symptoms or worsening of symptoms). At the time of diagnosis 64 (59%) were in New York Heart Association (NYHA) class I-II and 44 (41%) in NYHA class III-IV. After a mean follow-up of 46 +/- 21 months 6 patients died and 45 had worsening of symptoms. Univariate predictors of clinical outcome (death and worsening of symptoms) included left ventricular end-diastolic diameter (hazard ratio 1.03, P =.08), left ventricular end-systolic diameter (HR 1.04, P =.012), and left ventricular septum thickness (HR 1.14, P =.009) but not the degree of aortic obstruction. Multivariate predictors of clinical outcome were left ventricular septum thickness (P =.016) and left ventricular end-systolic diameter (P =.008).

CONCLUSION

In patients with various degrees of aortic stenosis the rate of clinical outcome is predicted by left ventricular function and septum thickness. Therefore both the left ventricular and aortic valve gradients should be taken into account when choosing the timing of intervention.

Echocardiographic predictors of survival in low gradient aortic stenosis

Echocardiographic predictors of long-term survival for patients with low gradient aortic stenosis who undergo aortic valve replacement have not been previously reported. This study shows that patients with larger pre- and postoperative left ventricular volumes, a lower mean preoperative aortic pressure gradient, and failure of volumes to decrease and ejection fraction to increase postoperatively may have a poor prognosis.

Aortic valvular replacement in octogenarians. Short-term and mid-term results in 140 patients

Aortic valvular replacements were performed between 1986 and 1995 at Rouen University Hospital on 140 octogenarians (52 male and 88 female). Pure or predominant aortic stenosis was present in 115 patients, 25 had associated aortic stenosis and insufficiency or predominant aortic insufficiency. Significant coronary lesions were present in 42% of patients. An isolated aortic valvular replacement was performed in 74% of patients, associated with a bypass in 23% and a bioprosthesis was used in 90%. Valvular lesions were mainly caused by Mönckeberg disease. Thirteen operative deaths occurred (9.3%). Functional recovery was satisfactory in 78%, mean hospital stay was 12 days. All well-known risk factors for aortic valvular replacement: age, coronary lesions, cardiac insufficiency, impaired ejection fraction and aortic insufficiency, led to an increase in operative mortality but were not statistically significant. Late mortality occurred in 28 patients, 99 patients are still alive at 4-91 months after surgery. The actuarial survival curve shows a 56.5% probability of surviving 5 years. Eighty per cent of survivors are able to live independently at home.

Results of aortic valve replacement for aortic stenosis with relatively low transvalvular pressure gradients

Fifty-two patients with low gradient critical aortic stenosis who underwent aortic valve replacement were found to have a perioperative mortality of 11% and an 8-year actuarial survival of only 29%. No hemodynamic variables, including valvular resistance, predicted long-term outcome, and the only clinical variable that predicted long-term survival was the absence of coronary artery disease.

Late survival after valve operation in patients with left ventricular dysfunction

BACKGROUND

Left ventricular dysfunction is a predictor of hospital mortality after cardiac valve operation. We evaluated late survival in a large cohort of these patients.

METHODS

From 1980 to 1993, 257 patients with a preoperative ejection fraction of 0.40 or less underwent aortic (n = 177), mitral (n = 72), or combined (n = 8) valve operation, with or without concomitant coronary artery bypass grafting.

RESULTS

Hospital mortality was 12.5%. Follow-up was 98% complete. Logistic regression analysis showed that an ejection fraction of less than 0.30, mitral regurgitation, concomitant coronary artery bypass grafting, emergency operation, and reoperation were independent correlates of hospital mortality (all at p < 0.05). Kaplan-Meier survival curves of the 220 hospital survivors showed a 65% 5-year survival. Multivariate analysis revealed preoperative use of diuretics, male sex, reoperation, age exceeding 60 years, and aortic regurgitation to be independent predictors of poor late outcome (all at p < 0.05).

CONCLUSIONS

The liability of left ventricular dysfunction with regard to diminished long-term survival is not completely reversed by valve operation. If operation is not performed before left ventricular dysfunction develops, postoperative medical treatment of these dilated, remodeled ventricles should be considered.

Effects of dobutamine on Doppler echocardiographic indexes of aortic stenosis

OBJECTIVES

This study sought to assess the diagnostic implications of the flow dependence of Doppler echocardiographic indexes of aortic valve stenosis.

BACKGROUND

Although valve area has been shown to change with alterations in flow rate, the diagnostic consequences of this phenomenon remain unknown. Valve resistance has been suggested as a more stable index for evaluating aortic stenosis.

METHODS

A low dose dobutamine protocol was performed in 35 patients with aortic stenosis. Hemodynamic indexes were obtained by Doppler echocardiography at baseline and at each dobutamine dose.

RESULTS

As a result of the shortening of the systolic ejection period, flow increased from (mean +/- SD) 164 +/- 48 to 229 +/- 102 ml/s (p < 0.0001). At peak flow, valve area increased by 28% (from 0.5 +/- 0.2 to 0.6 +/- 0.3 cm2, p < 0.0001), whereas valve resistance decreased by 4% (from 498 +/- 252 to 459 +/- 222 dynes.s.cm-5, p = 0.04). This observed change in resistance was smaller than that for valve area (p < 0.01). The flow dependence of valve area varied among individual patients (p < 0.0001). Multivariate analysis identified calcific degenerative etiology (beta 0.29, p = 0.002), left ventricular velocity of fiber shortening (beta 0.22, p = 0.01), baseline flow (beta -0.28, p = 0.04) and amount of flow increased induced by dobutamine (beta 0.90, p < 0.0001) as factors related to valve area flow dependence.

CONCLUSIONS

Although all Doppler echocardiographic indexes of aortic stenosis are affected by flow, valve resistance is more stable than valve area under dobutamine-induced hemodynamic changes. Baseline valve area may be unreliable in patients with calcific degenerative aortic stenosis and low output states.

Hemodynamic assessment of patients with low-flow, low-gradient valvular aortic stenosis

In aortic stenosis (AS), conventional indexes of severity vary with changes in transvalvular flow. It is important to determine the true severity of obstruction because AS in the presence of low cardiac output and low gradient is associated with high mortality during aortic valve replacement. This study compares 3 indexes of stenosis severity at different transvalvular flow rates in patients with low-flow, low-gradient critical AS. Eight patients with critical AS (valve area < or = 0.7 cm2), low cardiac output (< 4.0 L/min), and low mean transvalvular gradient (< or = 40 mm Hg) underwent hemodynamic assessment at baseline, after transvalvular flow was augmented with dobutamine, and after the valve opening was increased with percutaneous balloon aortic valvuloplasty. Severity of obstruction was assessed using 3 different measures: Gorlin formula calculated valve area, valvular resistance, and percentage left ventricular stroke work loss. Dobutamine infusion increased cardiac output by 35% and mean transvalvular gradient by 27%. The mean Gorlin formula calculated aortic valve area increased from 0.5 to 0.6 cm2 (p = 0.002). Percentage left ventricular stroke work loss increased from 23% to 28% (p = 0.03). Valve resistance was unchanged by dobutamine (350 to 310 dynes X sec X cm(-5); p = NS). Balloon valvuloplasty increased cardiac output 13% and decreased the gradient 31%; this resulted in an increase in the calculated valve area from 0.6 to 0.9 cm2 (p = 0.001). Percentage left ventricular stroke work loss decreased from 28% to 20% (p = 0.002), and valve resistance decreased from 310 to 181 dynes X sec X cm(-5) (p = 0.001) after valvuloplasty. We conclude that in patients with low-flow, low-gradient critical AS, valve resistance is the most flow-independent measure of severity of stenosis. All measures improve with percutaneous balloon aortic valvuloplasty.

Prognosis after valve replacement in patients with severe aortic stenosis and a low transvalvular pressure gradient

OBJECTIVES

This study was conducted to determine the risks and benefits of valve replacement in patients with severe aortic stenosis and a low transvalvular pressure gradient.

BACKGROUND

There is uncertainty regarding the appropriate management of adults with severe aortic stenosis and a transvalvular pressure gradient < or = 30 mm Hg. With only six such patients reported, one study suggested that these subjects have a prohibitive operative risk and little symptomatic improvement if they survive surgical treatment, whereas another showed that they can survive an operation and improve symptomatically.

METHODS

In an attempt to clarify the risks and benefits of valve replacement in these patients, we reviewed the records of 18 patients (15 men and 3 women, aged 49 to 81 years) with severe aortic stenosis (valve area < or = 0.4 cm2/m2 body surface area), a mean transvalvular pressure gradient < or = 30 mm Hg and limiting symptoms (New York Heart Association functional class III or IV) who underwent valve replacement.

RESULTS

Six patients (33%) (95% confidence interval 13% to 59%) died perioperatively, whereas 10 patients (56%) (95% confidence interval 31% to 78%) improved symptomatically to functional class I (n = 8) or II (n = 2) (p = NS in comparison with the 6 who died). No clinical or hemodynamic variable was predictive of survival or improvement in functional class.

CONCLUSIONS

Valve replacement in patients with severe aortic stenosis and a transvalvular pressure gradient < or = 30 mm Hg is accompanied by a considerable operative risk. Although there were no significant differences in this small series between the fraction of patients who died and those who exhibited improvement, we still recommend the procedure because many patients survive the operation and most of the survivors show an improved symptomatic status.

The treatment of aortic stenosis: is valvuloplasty ever an alternative to surgery?

The desire to extend the principle of balloon angioplasty to cardiac valve disease is understandable and commendable. Aortic valvuloplasty is associated, however, with an excessive complication rate, as reported by the Mansfield Scientific Aortic Valvuloplasty Registry (20.5% overall, including a 4.9% death rate within 24 hours and an additional 2.6% rate within 7 days for a 7.5% 1-week mortality). In contrast, the operative mortality for aortic valve replacement now ranges from 3%-5%, with perioperative complications far less than the one in five associated with valvuloplasty. Even if the two procedures had equivalent morbidity and mortality rates, the high incidence of restenosis (30%-60% range at 6 months) for the balloon technique precludes its widespread use for aortic stenosis. Despite the poor mid- and long-term results for balloon valvuloplasty, the procedure may have limited application in some clinical situations. Indeed, there are patients with concomitant systemic illnesses or advanced age ( greater than 80 years) who would not be good surgical candidates. In particular, valvular balloon dilation may be useful in bridging a seriously ill patient to a condition more favorable for replacement therapy. With few exceptions, however, valve replacement remains the gold standard for treatment of adult aortic stenosis.

Aortic valve resistance as an adjunct to the Gorlin formula in assessing the severity of aortic stenosis in symptomatic patients

OBJECTIVES

This study was conducted to determine the utility of aortic valve resistance in assessing the severity of aortic stenosis.

BACKGROUND

Assessment of the severity of aortic stenosis has traditionally employed hemodynamic data and the Gorlin formula to calculate the area of the aortic valve. Recently, flow dependence of the Gorlin formula has been identified and the accuracy of the formula challenged. Aortic valve resistance, the quotient of gradient and cardiac output, has been advanced as potentially useful in assessing the severity of valve stenosis.

METHODS

We studied 48 symptomatic patients with an initial diagnosis of severe aortic stenosis based on a calculated aortic valve area of less than or equal to 0.8 cm2 by the Gorlin formula. Forty of these patients (Group I) were confirmed to have severe aortic stenosis, whereas 8 (Group II) were subsequently proved not to have severe aortic stenosis. The 18 patients in Group I with a valve area of 0.6 to 0.8 cm2 (Group IA) were directly compared with Group II patients who had a similar valve area.

RESULTS

Aortic valve area was nearly identical in Group IA and Group II patients (0.69 +/- 0.05 and 0.71 +/- 0.06 cm2, respectively, p = NS). However, aortic valve resistance was much less in Group II patients (212 +/- 6 vs. 316 +/- 11 dynes.s.cm-5, p less than 0.0001). In this small cohort, aortic valve resistance achieved nearly complete separation of patients in Groups IA and II.

CONCLUSIONS

In some patients with relatively mild aortic stenosis, the calculated valve area may indicate that the stenosis is severe. The use of aortic valve resistance in conjunction with the Gorlin formula helps separate patients with truly severe aortic stenosis from those with milder disease.

Assessment of myocardial oxidative metabolism in aortic valve disease using positron emission tomography with C-11 acetate

C-11 acetate has recently been introduced as a tracer of myocardial oxidative metabolism with the use of positron emission tomography. To evaluate this approach in the pressure- or volume-loaded heart, C-11 acetate clearance rate constants were determined in 22 patients with chronic aortic valve disease and in nine normal subjects. Global myocardial C-11 clearance was significantly higher in patients with predominant aortic stenosis (n = 11) or aortic regurgitation (n = 11) than in normal subjects (0.069 +/- 0.017 min-1 and 0.072 +/- 0.010 min-1 compared with 0.050 +/- 0.004 min-1, p less than 0.05) and correlated significantly with the rate-pressure product corrected for mean aortic valve gradient (r = 0.73, p = 0.0001) for all studies. However, analysis of patient subgroups demonstrated that this correlation held only for aortic stenosis (r = 0.79, p less than 0.005 for gradient-corrected rate-pressure product). Additionally, C-11 clearance was strongly correlated with the product of heart rate and mean wall stress in patients with aortic stenosis (r = 0.89, p less than 0.005) but not in patients with aortic regurgitation. Normalization of C-11 acetate clearance rate constants for gradient-corrected rate-pressure product were significantly lower in patients with loaded ventricles, particularly in the presence of a low ejection fraction, compared to normal subjects. Possible mechanisms include myocardial adaptation through hypertrophy or depressed contractility, which would both tend to reduce oxygen consumption under any given load. Serial comparison of C-11 acetate kinetics and noninvasive indexes of oxygen demand may provide assessment of disease progression in pathologic ventricular loading.