Aortic Dissections in the Elderly

Michael E. DeBakey died on 11 July 2008. Although his death marked the end of an era, the circumstances surrounding the surgery for his acute dissection revealed all of the challenges that we as cardiovascular surgeons face when treating the elderly.¹ Repair of acute type A aortic dissection (ATAAD) (or DeBakey type 1 or 2 dissection) might be the most demanding cardiovascular procedure that we perform: although improvements have been made over the past 5 decades, the early operative mortality rate remains as high as 25%.² Because nonoperative management is still associated with a dismal prognosis (most patients die within weeks), surgery is usually offered. Recent studies, however, have questioned the practicality of intervention in the elderly.³

What Is the Concern?

As our population ages, the number of elderly who experience acute aortic dissection will inevitably rise, further increasing the likelihood that we will encounter this situation. According to the 2010 United States Census, the population of those older than 70 years has grown 8.5% since 2000, to a total of 27.8 million people.⁴ More striking was the increase in those older than 80 years—“octogenarians,” whose numbers grew at a rate of 18.3% over the same period, for a total of 11.2 million people. If one assumes that acute aortic dissection occurs at an annual incidence of 5 per 100,000 people, and this is probably an underestimate, then as many as 560 octogenarians (or older) will suffer acute aortic dissection in the U.S. every year. If we think that 18.3% growth is significant, then consider the 50- to 69-year-old group, the fastest growing subgroup in the U.S., which grew at a rate of 27.8% over the same period. By the next census tabulation in 2020, the 50-and-above group of patients may total 71.2 million. Many of these people will be considered elderly. Dissection in the elderly remains a real concern.

How Old Is “Old”?

What is considered old? The international registry of acute dissection (IRAD)—a voluntary registry of patients with acute type A aortic dissection (both operated-upon and not)—examined this question and identified age greater than 70 years as a risk factor for early death from dissection.² This study found that the octogenarian patient group was the one most frequently managed nonoperatively. Moreover, early death was no different when octogenarians were compared with septuagenarians, whether the dissection was repaired or managed nonoperatively.

Accordingly, the IRAD results suggest that an age between 70 and 80 years is a risk factor for poor outcome from open repair of ATAAD and should be considered “elderly.”

“As Surgeons, We Live in the Numerator.”^*

Since DeBakey and Cooley's early reports of excellent outcomes after operative repair of aortic dissection, the surgical community has tended to emphasize positive-outcome studies and rarely has reported failures.⁵ In 2001, however, Neri and colleagues³ reported an experience involving 24 octogenarian patients who underwent open repair of ATAAD with frankly dismal results. The authors reported an intraoperative mortality rate of 33%, a hospital mortality rate of 83%, and no 6-month survivors. As a result of this experience, the authors concluded that “older patients should be denied such complicated surgical interventions to conserve resources….”³

In response to this report, several groups have since published reports on ATAAD repair in the octogenarian population. For example, Hata and colleagues⁶ reported from Japan on a series of 58 octogenarians who presented with ATAAD, of whom 30 underwent emergent repair and 28 were managed medically. The early mortality rate was significantly lower in the repaired group than in the medically managed group, 13.3% versus 60.7%, P=0.0003. Notable, however, was the fact that midterm survival was not significantly different between groups, both of which experienced about 40% survival at 8 years.⁶ One of the limitations in this study, however, was the fact that the incidence of ATAAD intramural hematoma was not reported. It has been suggested that intramural hematoma has a more benign natural history than does typical aortic dissection, especially in the Asian population.

Piccardo and associates' multicenter report from Europe noted an in-hospital mortality rate of 46% in its examination of 57 octogenarians. Similar to the study by Hata, however, survival beyond 1 year remained reasonable, at about 50% at 5 years.^7,8

Subsequently, a pooled analysis of ATAAD in the octogenarian was performed by Biancari and colleagues.⁹ In this report, a 37% early mortality rate and 12% incidence of stroke were observed in 308 octogenarians. On the basis of these results, it becomes apparent that open repair should be considered for most octogenarians; but we must accept the fact that the early mortality rate will be high. Unfortunately, few data exist regarding functional outcome and quality of life of this patient cohort after ATAAD repair. At any rate, median and late survival appear to be reasonable, because almost 50% of the deaths occurred by the end of the first year. The challenge comes in predicting which patients will survive beyond the first year with a reasonable quality of life.

How Do We Predict Outcome?

Risk calculators, such as the Society for Thoracic Surgery (STS) risk score and the EuroSCORE, provide risk stratification for cardiovascular surgery. These, however, were developed for coronary artery and valvular heart disease procedures, not for complex aortic surgery. Although risk factors for ATAAD repair have been identified (these include old age, rupture, malperfusion, hypotension, stroke, previous cardiac surgery, and renal dysfunction), a reliable predictive index has not been developed and validated.²

Recently, frailty has gained interest in the prediction of surgical outcomes. Many differing indices suggest the usefulness of frailty as a predictor in general surgery, but less is known about its worth in application to cardiac surgery.^10–12 Recent work with transcatheter aortic valve replacement has applied several criteria to the measurement of frailty.¹³ These include the Katz Activities of Daily Living, grip strength, performance in the 15-foot walk, and albumin level.¹⁴

Whether such indices are any better than the “eyeball” test has yet to be determined in application to aortic surgery. In any event, an objective method to determine frailty is still needed.

To Cut or Not to Cut? That Is the Question

Until better predictors are available, each ATAAD patient should be considered individually regarding the decision to operate. Factors that require consideration relate to the patient, the surgeon, and the available facility. Surgeons who emergently encounter ATAAD should choose the repair that they are most capable of performing—even in the circumstance that late reoperation will be necessary. Consideration of the operating facility becomes crucial, because blood banking, anesthesiology, and nursing should be adequate to support both surgeon and patient. Transfer to cardiovascular centers with long experience in treating aortic conditions should be considered when appropriate. Factors unique to the patient are listed in Table I.

Table I. Patient Factors: To Cut or Not to Cut

Conclusion

In the future, we hope to have tools that enable a more accurate prediction of outcome after complex aortic surgery in the elderly. These tools will provide the ability to better counsel patients. The final decision on whether “to cut or not to cut” will need to be individualized, always taking into account the wishes of first the patient, and then the family.¹⁵