K. Hoercher

Ventilatory and Heart Rate Responses to Exercise: Better Predictors of Heart Failure Mortality Than Peak Oxygen Consumption

BACKGROUNDnAn abnormally low chronotropic response and an abnormally high ventilatory response (V(E)/V(CO2)) to exercise are common in patients with severe heart failure, but their relative prognostic impacts have not been well explored.nnnMETHODS AND RESULTSnConsecutive patients with heart failure referred for metabolic stress testing who were not taking beta-blockers or intravenous inotropes (n=470) were followed for 1.5 years. The chronotropic index was calculated while peak V(O2) and V(E)/V(CO2) were directly measured. Chronotropic index and peak V(O2) were considered abnormal if in the lowest 25th percentiles of the patient cohort, whereas V(E)/V(CO2) was considered abnormal if in the highest 25th percentile. For comparative purposes, a group of 17 healthy controls underwent metabolic testing as well. Compared with controls, heart failure patients had markedly abnormal ventilatory and chronotropic responses to exercise. In the heart failure cohort, there were 71 deaths. In univariate analyses, predictors of death included high V(E)/V(CO2) low chronotropic index, low V(O2), low resting systolic blood pressure, and older age. Nonparametric Kaplan-Meier plots demonstrated that by dividing the population according to peak V(E)/V(CO2) and peak V(O2), it is possible to identify low, intermediate, and very high risk groups. In multivariate analyses, the only independent predictors of death were high V(E)/V(CO2) (adjusted relative risk [RR] 3.20, 95% CI 1.95 to 5.26, P<0.0001) and low chronotropic index (adjusted RR 1.94, 95% CI 1.18 to 3.19, P=0.0009).nnnCONCLUSIONSnThe ventilatory and chronotropic responses to exercise are powerful and independent predictors of heart failure mortality.

Risk Factors for Death After Heart Transplantation: Does a Single-Center Experience Correlate With Multicenter Registries?

BACKGROUNDnRisk factors for death after heart transplantation (Tx) are frequently documented from multicenter registries. Although this information is helpful, it reflects a whole range of experiences and results, and may not translate to a particular center. This study was performed to (1) evaluate pre-Tx factors affecting mortality in a single-center experience, and (2) compare these factors with risk factors obtained from multicenter registry reports.nnnMETHODSnReview of our transplant database between January 1984 and December 1995 identified 405 adults who received a primary heart Tx. Multiple factors were analyzed, including demographics, Tx era, cytomegalovirus status, United Network for Organ Sharing status of recipient, presence of pulmonary hypertension, previous cardiac operations, mechanical ventilation or circulatory support, ischemia time, number of rejection episodes, and preoperative flow cytometry crossmatching.nnnRESULTSnOne- and 5-year survival rates were 87.8% and 73.4%, respectively (Kaplan-Meier). Contrary to multicenter registry reports, our data indicate that reoperative procedures, left ventricular assist device support, increasing donor and recipient age, and ischemia time up to 4.2 hours are not risk factors for death after Tx. Likewise, mode of donor death is not a risk factor affecting outcome. Significant risk factors for mortality identified by multivariate analysis included early transplant era (1984 to 1989; p = 0.002), female donor (p = 0.042), cytomegalovirus-seropositive donor (p = 0.048), high pulmonary vascular resistance (p = 0.018), and intraaortic balloon pump support (p = 0.03). It also identified a positive B-cell flow cytometry crossmatch (p = 0.015) to be a risk factor with univariate analysis.nnnCONCLUSIONSnOur data identify a group of recipients, reportedly at high risk in multicenter registries, who are not at increased risk of death after Tx. This information supports the growing experience with older donors and recipients and with bridged transplants, and has allowed us to expand our donor pool. These prognostic factors at evaluation allow more liberal selection of patients and donors for transplantation.

Bench repair of donor mitral valve before heart transplantation

Bench repair of the donor mitral valve was performed before orthotopic heart transplantation in a 57-year-old status I recepient. Mitral regurgitation in the structurally normal mitral valve was due to annular dilatation at the attachment of the posterior leaflet and was corrected with posterior annuloplasty. The patient is clinically well 18 months after transplantation.

Regional referral system for patients with acute mechanical support: experience at the Cleveland Clinic Foundation.

Regional referral networks (“hub and spoke”) have been created to facilitate the transfer of patients on mechanical circulatory support. Although individual centers report good success, overall outcomes have remained poor. We investigated whether preoperative variables influenced survival and could be used to help select patients best served by referral. A retrospective chart review was conducted on all patients transferred to our institution supported on cardiac assist devices. Between January 1995 and September 2003, 39 patients were received in transfer for continued care after the implantation of a cardiac assist device. Eighty-five percent of patients had the ABIOMED BVS 5000 implanted. The most common indication was postcardiotomy shock. Sixty-four percent of patients were not candidates for heart transplantation due to medical or social contraindications. The 30-day mortality of this group was 62%. Survivors had less comorbidity and were less likely to have complex surgeries, neurologic impairment, and multisystem organ failure when presenting to our center. Devices were weaned in 30% of cases. Only six patients (15%) were successfully transplanted, and five of these patients have done well at follow-up. Based on our experience, we believe that cardiogenic shock patients benefit from a regional referral system if they have not had complex cardiac surgical procedures or developed multisystem organ failure. Furthermore, there is a survival advantage when using long-term devices because this allows possible recovery or transplantation.

Hospital transfer of patients for LVAD bridge to transplant: is timing really critical to success?

Background: Implantable left ventricular devices (LVAD) as bridge to transplant (BTT) are used to salvage critically ill patients who would not survive without aggressive mechanical support. This strategy has resulted in the development of established referral patterns to experienced transplant centers with an emphasis on early transfer which is thought to be critical to successful outcomes. We reviewed our experience with patients transferred from outside hospitals in an effort to elucidate risk factors which may predict poor outcome. Methods: We retrospectively reviewed data on 202 patients who completed LVAD/BTT support between December 1991 and October 2000. Of those, 134 (66%) were transferred from outside hospitals (median stay5 5 days). In these 134 pts, indications for transfer included, 40% acute MI (28% , 3days, 12% 3-7days),13% post-cardiotomy, and 47% other. 7/134 pts were transferred on ECMO or Abiomed and 27/134 underwent ECMO placement at our institutuion (median time until placement 51 day). Median time from admission until LVAD support was 3 days. Results: Survival until transplant for these 134 pts was 68% with the median duration of support 79 days (range50-324). The patient group at highest risk for death on support were those transferred within 24 hours of their initial hospitalization (n538 pts) versus those transferred . 24 hrs( 47% vs 27%, p50.03). One explanation may be that this group represented a more critically ill population, including acute MI (61% vs 9% . 24 hrs, p50.0001), need for Abiomed or ECMO (47% vs 19% p50.001), and ischemic disease 91% vs 62% p50.002). Conclusion: Transfer of critically ill patients to undergo LVAD/ BTT is associated with an overall good survival, however, in a subset of patients who have severe hemodynamic compromise associated with acute MI, ischemia, and need for Ecmo or Abiomed, mortality is high despite the strategy of very early transfer (, 24 hrs)and intervention.