Peak oxygen uptake during cardiopulmonary exercise testing determines response to cardiac resynchronization therapy.

BACKGROUND: Cardiac resynchronization therapy (CRT) is an established treatment modality for advanced heart failure (HF) but 20-30% of patients treated with CRT do not experience clinical improvement. Hence, in this study we aimed to investigate whether baseline cardiopulmonary exercise testing (CPX) can help improve the prediction of a positive functional CRT response. METHODS: This prospective observational study included 76 HF patients undergoing elective CRT implantation and clinical CPX and echocardiographic assessment were performed at baseline, 6, and 12 months. RESULTS: Peak VO2 increased from 11.0±2.5 ml/min/kg to 12.0±4.1 ml/min/kg and 12.2±3.5 ml/min/kg at 6 and 12 months after CRT, respectively. The number of patients classified as "CRT-responders" (Δ peak VO2≥1 ml/kg/min) was 33 (46%) and 36 (52%) at 6 and 12 months after CRT, respectively. Patients with baseline peak VO2<40% of predicted (lowest tertile) demonstrated a 68% and 69% response rate at 6 and 12 months, respectively, as compared to a 35% and 42% response rate among patients with baseline peak VO2≥40% of predicted (p=0.01 and p=0.02, respectively). In multivariate analysis patients with baseline peak VO2<40% of predicted had an adjusted odds ratio of 4.4 (95% CI 1.6-12.5; p<0.01) and 3.1 (95% CI 1.1-8.8; p=0.03) for positive CRT response at 6 and 12 months, respectively. CONCLUSIONS: Treatment with CRT improves exercise capacity but this increase is most substantial among patients with a lower baseline peak VO2 (% of predicted). Baseline CPX can, therefore, be utilized to identify patients more likely to exhibit a functional improvement after CRT.

Prognostic value of cardiac troponin T in patients with moderate to severe heart failure scheduled for cardiac resynchronization therapy.

BACKGROUND: Predicting response to cardiac resynchronization therapy (CRT) is challenging. Highly sensitive cardiac troponin T (hsTnT) might predict response to CRT and identify patients at a high risk of experiencing severe cardiovascular events. We investigated whether baseline levels of hsTnT were associated with response to CRT and with severe cardiovascular events after long-term follow-up. METHODS: Eighty-one consecutive patients were included according to the current guidelines for CRT. Biochemical, functional, and clinical parameters were assessed at baseline and at 3, 6, and 12 months of follow-up; and mortality/cardiac transplantation after 46 ± 6 months of follow-up was investigated. Cardiac magnetic resonance imaging and echocardiography were used to assess left ventricular function including viability and remodeling. RESULTS: Seventy-five patients completed 12 months of follow-up; and after a follow-up of 46 ± 6 months, a total of 15 patients died, 13 of these from cardiovascular causes, and 7 underwent heart transplantation. Baseline hsTnT <15 ng/L predicted response to CRT and was associated with a more favorable outcome with regard to severe cardiovascular events. Multivariate analysis found that presence of transmural scar tissue/fibrosis on magnetic resonance imaging and use of statins were independently associated with higher concentrations of hsTnT at baseline. There was a strong correlation between hsTnT and N-terminal pro-B-type natriuretic peptide levels. CONCLUSIONS: Highly sensitive TnT levels were elevated in the majority of heart failure patients who were scheduled for CRT. The HsTnT levels predicted response to CRT as well as long-time survival.

Prognostic importance of renal function 1 year after heart transplantation for all-cause and cardiac mortality and development of allograft vasculopathy.

BACKGROUND: Impaired renal function is associated with increased mortality among heart failure patients. Although a significant proportion of heart transplant (HTx) recipients have reduced renal function at 1 year post-HTx, no previous study has evaluated the associated risk for both all-cause and cardiac mortality. Hence, we assessed the relationship between glomerular filtration rate (GFR) at 1 year post-HTx and all-cause and cardiac mortality and development of cardiac allograft vasculopathy (CAV). METHODS: We evaluated 381 patients with a minimum survival of 1 year post-HTx and the Modification of Diet in Renal Disease Study formula was used to calculate estimated GFR. Mortality and angiographic CAV were defined as separate endpoints, and median follow-up was 7.4 and 4.0 years, respectively. RESULTS: During the follow-up period, 122 patients died and 154 patients developed CAV. Reduced GFR pre-HTx was not a risk factor for either endpoint. Overall, 193 (51%) patients had GFR <60 ml/min/1.73 m at one year post-HTx and this was an independent predictor of all-cause mortality with an adjusted hazard ratio of 1.7 (P=0.01) for a GFR between 30-60 and 3.2 (P=0.006) for GFR <30 ml/min/1.73 m. GFR <60 ml/min/1.73 m at 1 year post-HTx was also associated with a higher risk of cardiac mortality (HR=1.9; P=0.04) but did not predict the development of CAV. CONCLUSIONS: Renal impairment is evident in a majority of HTx recipients at 1 year post-HTx. It is an important risk factor for both all-cause and cardiac mortality but does not predict the development of angiographic CAV.