Gerin R. Stevens

Effect of an American Heart Association Get With the Guidelines program-based clinical pathway on referral and enrollment into cardiac rehabilitation after acute myocardial infarction.

Cardiac rehabilitation (CR)/secondary prevention programs are an important part of patient care after acute myocardial infarction (AMI). However, only 10% to 15% of eligible patients enroll in such programs. The purpose of this study was to evaluate the effect of an American Heart Association Get With the Guidelines (GWTG)-based clinical pathway on referral and enrollment into CR after AMI. Patients (n = 780) admitted to a single center during an 18-month period with AMI and discharged to home were evaluated retrospectively for referral and enrollment into CR programs. A total of 714 patients (92%) were on the GWTG pathway; 392 (55%) were referred and 135 (19%) were enrolled into CR. Higher referral was associated with pathway use (odds ratio [OR] 2.3, 95% confidence interval [CI] 1.1 to 4.9, p = 0.03), percutaneous coronary intervention (OR 3.1, 95% CI 1.9 to 5.2, p <0.0001), and in-patient physical therapy consultation (OR 13, 95% CI 8.2 to 20.5, p <0.0001). Ethnicity did not affect referral, but was the only variable associated with lower enrollment. Hispanic and black patients had 92% (OR 0.08, 95% CI 0.01 to 0.55, p = 0.02) and 57% (OR 0.43, 95% CI 0.19 to 1.05, p = 0.06) lower odds to enroll compared with white patients, respectively. In conclusion, use of the American Heart Association GWTG pathway showed a significantly higher referral rate to CR after AMI than previously reported in the literature. Nonetheless, most referred patients did not enroll. Strategies to bridge the gap between referral and enrollment in CR should be incorporated into AMI clinical pathways, with special emphasis on increasing enrollment in ethnic minorities.

RV dysfunction in pulmonary hypertension is independently related to pulmonary artery stiffness.

OBJECTIVES This study investigated whether right ventricular (RV) adaptation to chronic pressure overload is associated with pulmonary artery (PA) stiffness beyond the degree of severity of pulmonary hypertension (PH). BACKGROUND Increased PA stiffness has been associated with reduced survival in PH. The mechanisms for this association remain unclear. METHODS Right heart catheterization and cardiac magnetic resonance were performed within 1 week in 124 patients with known or suspected chronic PH. Pulmonary vascular resistance index (PVRI) and PA pressures were quantified from right heart catheterization. Cardiac magnetic resonance included standard biventricular cine sequences and main PA flow quantification with phase-contrast imaging. Indexes of PA stiffness (elasticity, distensibility, capacitance, stiffness index beta, and pulse pressure) were quantified combining right heart catheterization and cardiac magnetic resonance data. RV performance and adaptation were measured by RV ejection fraction, right ventricular mass index (RVMI), RV end-systolic volume index, and right ventricular stroke work index (RVSWI). RESULTS All indexes of PA stiffness were significantly correlated with measures of RV performance (Spearman rho coefficients ranging from -0.20 to 0.61, p < 0.05). Using multivariate regression analysis, PA elasticity, distensibility, and index beta were independently associated with all measures of RV performance after adjusting PVRI (p ≤ 0.024). PA capacitance was independently associated with RV ejection fraction, RVMI, and RVSWI (p < 0.05), whereas PA pulse pressure was associated with RVMI and RVSWI (p ≤ 0.027). Compared with PVRI, PA elasticity, distensibility, capacitance, and index beta explained 15% to 68% of the variability in RV ejection fraction, RVMI, and RV end-systolic volume index. Relative contributions of PA stiffness for RVSWI were 1.2× to 18.0× higher than those of PVRI. CONCLUSIONS PA stiffness is independently associated with the degree of RV dysfunction, dilation, and hypertrophy in PH. RV adaptation to chronic pressure overload is related not only to the levels of vascular resistance (steady afterload), but also to PA stiffness (pulsatile load).

Readmissions After Ventricular Assist Device: Etiologies, Patterns, and Days Out of Hospital

BACKGROUND Scarce literature exists describing the patterns of readmission after continuous flow left ventricular assist device (CF-LVAD) implantation. These carry significant cost and quality of life implications. We sought to describe the etiology and pattern of readmission among patients receiving CF-LVADs. METHODS Frequency, reason, urgency, and duration of readmission as well as freedom from readmission were examined in a retrospective review of our institutional experience. As an indirect means of quality of life, the ratio of days out of hospital (OOH)/days alive with device was calculated. RESULTS From 2006 to 2011, 71 adult patients implanted with a CF device were included. Indication for device implantation was bridge to transplant (n=19), potential bridge to transplant (n=25), or destination therapy (n=27). Length of support averaged 359 days. Total support time was 69.7 patient years. One hundred fifty-five readmissions accounted for a total of 1,659 hospital days. Fifty-six patients were readmitted during the study period. Median time to first readmission was 48 days (range 2 to 663 days). Median length of stay was 5 days. The single most common etiology for readmission was gastrointestinal bleeding accounting for 14% of readmissions. Readmissions were urgent (87%), elective (10%), or life-threatening (3%). Patients on the average enjoyed 92% of their time OOH. CONCLUSIONS Patients undergoing CF-LVAD support are often readmitted within 6 months of discharge. Readmissions tend to be of short duration and the most common reason is for gastrointestinal bleeding. Importantly, following discharge after implant procedure, 51 patients spent at least 90% of days OOH.

Risk stratification of ambulatory patients with advanced heart failure undergoing evaluation for heart transplantation.

BACKGROUND Risk stratification of ambulatory heart failure (HF) patients has relied on peak VO(2)<14 ml/kg/min. We investigated whether additional clinical variables might further specify risk of death, ventricular assist device (VAD) implantation (INTERMACS <4) or heart transplantation (HTx, Status 1A or 1B) within 1 year after HTx evaluation. We hypothesized that right ventricular stroke work index (RVSWI), pulmonary capillary wedge pressure (PCWP) and the model for end-stage liver disease-albumin score (MELD-A) would be additive prognostic predictors. METHODS We retrospectively collected data on 151 ambulatory patients undergoing HTx evaluation. Primary outcomes were defined as HTx, LVAD or death within 1 year after evaluation. RESULTS Average age in our cohort was 55 ± 11.1 years, 79.1% were male and 39% had an ischemic etiology (LVEF 21 ± 10.5% and peak VO(2) 12.6 ± 3.5 ml/kg/min). Fifty outcomes (33.1%) were observed (27 HTxs, 15 VADs and 8 deaths). Univariate logistic regression showed a significant association of RVSWI (OR 0.47, p = 0.036), PCWP (OR 2.65, p = 0.007) and MELD-A (OR 2.73, p = 0.006) with 1-year events. Stepwise regression showed an independent correlation of RVSWI<5gm-m(2)/beat (OR 6.70, p < 0.01), PCWP>20 mm Hg (OR 5.48, p < 0.01), MELD-A>14 (OR 3.72, p< 0.01) and peak VO(2)<14 ml/kg/min (OR 3.36, p = 0.024) with 1-year events. A scoring system was developed: MELD-A>14 and peak VO(2)<14-1 point each; and PCWP>20 and RVSWI<5-2 points each. A cut-off at≥4 demonstrated a 54% sensitivity and 88% specificity for 1-year events. CONCLUSIONS Ambulatory HF patients have significant 1-year event rates. Risk stratification based on exercise performance, left-sided congestion, right ventricular dysfunction and liver congestion allows prediction of 1-year prognosis. Our findings support early and timely referral for VAD and/or transplant.

Outcomes of cardiac transplantation in septuagenarians

BACKGROUND Cardiac transplantation in many centers is programmatically limited to patients aged younger than 70 years. We investigated the trends and outcomes for cardiac transplantation in recipients aged 70 years and older in the United States. METHODS De-identified data were provided by United Network of Organ Sharing. Transplant recipients were grouped by age 60-69 years and 70 years and older. Univariate comparisons were performed using Students t-test or the Pearson chi-square test. Survival was estimated using the Kaplan-Meier technique and compared with the log-rank test. Cox regression was used to determine predictors of death after transplant. Statistical significance was assigned to p < 0.05. RESULTS Between January 1, 1998, and June 15, 2010, 5,807 sexagenarians and 332 septuagenarians received allografts. The septuagenarian cohort had more men, less diabetes, was less likely to have a ventricular assist device, and more likely to be status II. Donors for septuagenarians were older and died more frequently from intracranial hemorrhage. Median unadjusted survival was 9.8 years for sexagenarians vs 8.5 years for septuagenarians (p = 0.003). There was no difference in the incidence of cerebrovascular accident, length of stay, or pacemaker need between groups. Septuagenarians were less likely to be treated for rejection the first year (p = 0.001). Age was a multivariate predictor of death (hazard ratio, 1.289; 95% confidence interval, 1.039-1.6; p = 0.021). CONCLUSIONS Selected septuagenarians with advanced heart failure can derive great benefit from cardiac transplantation, although survival is inferior to that of an immediately younger sexagenarian cohort. Most of the mortality risk is seen in the first year after transplantation. A reduced incidence of rejection was observed and warrants further study.

New index alpha improves detection of pulmonary hypertension in comparison with other cardiac magnetic resonance indices

BACKGROUND Cardiovascular magnetic resonance (CMR) has been proposed for the evaluation of patients with pulmonary hypertension (PH). However, there is no consensus on the optimal method for PH diagnosis using CMR. OBJECTIVE To compare the diagnostic ability of multiple CMR-derived indices for the detection of PH as determined by right heart catheterization (RHC). METHODS A total of 185 patients with known or suspected chronic PH who underwent cardiac CMR and RHC in ≤15 days were included. PH was defined as a mean pulmonary artery (PA) pressure ≥25 mmHg. Right ventricular (RV) volumes, RV ejection fraction (RVEF), PA areas, and PA average blood flow velocity were quantified with CMR. A novel index α was defined as the ratio between minimal PA area and RVEF. RESULTS According to the RHC, PH was present in 152 patients. All CMR-derived parameters correlated with the degree of mean PA pressure, with α having the highest correlation coefficient (r=0.61, p<0.001). Correlations were also highest for α in the patients with pulmonary arterial hypertension (PAH; r=0.55, p<0.001) and non-PAH subgroup (r=0.61, p<0.001). Diagnostic accuracy for the detection of PH, based on receiver operating curve analysis, was best for α (area under the curve=0.95). A cutoff value of 7.2 demonstrated a sensitivity of 90% and a specificity of 88%. CONCLUSIONS An easily-obtainable and novel CMR index α that combines geometrical and functional information of the PA and the RV allows for the noninvasive diagnosis of PH with high accuracy, above other common CMR-derived parameters.

Exercise Performance in Patients With Pulmonary Hypertension Linked to Cardiac Magnetic Resonance Measures

BACKGROUND The 6-minute walk distance (6MWD) is a useful measure of functional class and has been shown to predict mortality in patients with pulmonary hypertension (PH). Determinants of functional class in PH are incompletely understood. We hypothesized that cardiovascular structure and function, as determined by cardiac magnetic resonance (CMR) imaging, and cardiac hemodynamics, as determined by right heart catheterization (RHC), would predict 6MWD in adult patients with PH. METHODS Forty-three patients (32 women) with PH underwent RHC, CMR and 6MWD testing within a 3-month period. The 6MWD was correlated with RHC and CMR variables using Spearman rho (r) coefficients. These relationships were further evaluated using linear regression analysis. RESULTS Median 6MWD was 233.2 (interquartile range 161.6 to 338.4) meters. The 6MWD was correlated with pulmonary artery (PA) elasticity (r = 0.42, p = 0.006), PA average blood flow velocity (r = 0.38, p = 0.014), right ventricular stroke volume index (RVSVI; r = 0.41, p = 0.008), left ventricular SVI (LVSVI; r = 0.36, p = 0.018) and RV stroke work index (RVSWI; r = 0.37, p = 0.017). These associations remained significant after adjustment for age, gender, body mass index and the presence of lung disease. Exercise performance did not correlate with commonly measured indices such as ventricular volume, ejection fraction or pulmonary pressure. CONCLUSIONS Stroke volume index, PA elasticity and PA average blood flow velocity are novel CMR parameters associated with functional class in PH. CMR can provide insights into determinants of exercise performance and may be a useful tool to non-invasively monitor cardiovascular status in patients with PH.

Serial phase-contrast MRI for prediction of pulmonary hemodynamic changes in patients with pulmonary arterial hypertension.

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PULMONARY ARTERY STIFFNESS IS INDEPENDENTLY ASSOCIATED WITH THE DEGREE OF RIGHT VENTRICULAR DYSFUNCTION IN PULMONARY HYPERTENSION

Results: Using Spearman correlation, PA elasticity and distensibility were significantly associated with RVMI and RVEF (Figure, p-values<0.001). Using multivariate regression analysis, elasticity was independently associated with RVMI and RVEF, respectively, after adjusting for age, gender, ethnicity, and mPAP (β = -0.002, p=0.046 or β = 0.26, p= 0.002) or pulmonary vascular resistance index (PVRI; β = -0.003, p=0.003 or β = 0.29, p<0.001). Distensibility was independently associated with RVMI and RVEF, respectively, after adjusting for age, gender, and ethnicity, but remained significant only after further adjustment for PVRI (β = -0.025, p=0.032 or β = 3.0, p=0.004) and not mPAP.