Patricia A. Lowry

Metabolite profiling of blood from individuals undergoing planned myocardial infarction reveals early markers of myocardial injury

Emerging metabolomic tools have created the opportunity to establish metabolic signatures of myocardial injury. We applied a mass spectrometry-based metabolite profiling platform to 36 patients undergoing alcohol septal ablation treatment for hypertrophic obstructive cardiomyopathy, a human model of planned myocardial infarction (PMI). Serial blood samples were obtained before and at various intervals after PMI, with patients undergoing elective diagnostic coronary angiography and patients with spontaneous myocardial infarction (SMI) serving as negative and positive controls, respectively. We identified changes in circulating levels of metabolites participating in pyrimidine metabolism, the tricarboxylic acid cycle and its upstream contributors, and the pentose phosphate pathway. Alterations in levels of multiple metabolites were detected as early as 10 minutes after PMI in an initial derivation group and were validated in a second, independent group of PMI patients. A PMI-derived metabolic signature consisting of aconitic acid, hypoxanthine, trimethylamine N-oxide, and threonine differentiated patients with SMI from those undergoing diagnostic coronary angiography with high accuracy, and coronary sinus sampling distinguished cardiac-derived from peripheral metabolic changes. Our results identify a role for metabolic profiling in the early detection of myocardial injury and suggest that similar approaches may be used for detection or prediction of other disease states.

Ventricular Arrhythmia Following Alcohol Septal Ablation for Obstructive Hypertrophic Cardiomyopathy

We sought to assess the risk of sudden cardiac death (SCD) and ventricular arrhythmia after alcohol septal ablation (ASA) for obstructive hypertrophic cardiomyopathy. ASA is a nonsurgical alternative to septal myectomy for treatment of symptomatic, drug-refractory, obstructive hypertrophic cardiomyopathy. The effect of ASA on ventricular arrhythmia risk is not well established. We examined the rates of SCD among 89 patients treated with ASA. The secondary end point was ventricular tachycardia/ventricular fibrillation (VT/VF), appropriate implantable cardioverter defibrillator (ICD) therapy, or cardiac arrest after ASA among those with implanted ICDs or permanent pacemakers (n = 42). Patients were classified as either high-risk or low-risk on the basis of established clinical indications for ICD implantation. No mortality was attributable to SCD at a mean follow-up of 5.0 +/- 2.3 years in the entire cohort. Among the 42 patients with an ICD or permanent pacemaker, 9 had documented VT/VF, cardiac arrest, or appropriate ICD therapy, resulting in an annual event rate of 4.9%/year. The annual event rate for VT/VF, cardiac arrest, or appropriate ICD therapy was 2.8%/year (4 of 29 patients) in low-risk patients and 13.4% in high-risk patients (5 of 13 patients). A 10-mm Hg increase in the immediate post-ASA gradient was associated with a hazard ratio of 2.66 for arrhythmic events (95% confidence interval 1.55 to 4.56, p <0.001). In conclusion, ASA was performed in patients with highly symptomatic, drug-refractory hypertrophic cardiomyopathy with no mortality attributable to SCD and an annual rate of VT/VF, cardiac arrest, or appropriate ICD therapy of 4.9%/year.

Pathological effects of alcohol septal ablation for hypertrophic obstructive cardiomyopathy

Background: The pathological effects and the mechanisms of action of intracoronary administration of ethanol for alcohol septal ablation (ASA) for the management of hypertrophic obstructive cardiomyopathy (HOCM) are unknown. Methods: We examined surgical specimens and, in one case, autopsy specimens from four patients who underwent surgical septal myectomy 2 days to 14 months after unsuccessful ASA. Results: Pathological examination early after ASA showed coagulative necrosis of both the myocardium and the septal perforator arteries. Affected arteries were distended and occluded by necrotic intraluminal debris, without platelet–fibrin thrombi. Late after unsuccessful ASA, excised septal tissue was heterogeneous, containing a region of dense scar, and adjacent tissue containing viable myocytes and interspersed scar. Conclusions: Intracoronary administration of ethanol in patients with HOCM causes acute myocardial infarction with vascular necrosis. The coagulative necrosis of the arteries, their distension by necrotic debris and the absence of platelet–fibrin thrombi distinguish ethanol-induced infarction from that caused by atherosclerotic coronary artery disease. The direct vascular toxicity of ethanol may be an important aspect of the mechanism of successful ASA.

Management strategy in 249 consecutive patients with obstructive hypertrophic cardiomyopathy referred to a dedicated program.

The likelihood of success of conservative management of obstructive hypertrophic cardiomyopathy (HC) and the predictors of failure of conservative therapy are not known. We therefore evaluated the efficacy of an algorithm for the management of symptoms and predictors of failed conservative therapy in 249 consecutive symptomatic patients with obstructive HC referred to a dedicated HC program for management in general or for septal reduction therapy (SRT) in particular. There was considerable practice variation in the extent to which conservative therapy was optimized before referral for SRT. Over 3.7 ± 2.9-year follow-up, symptoms resolved with addition of or increase in dosage of a β blocker, calcium channel blocker, or disopyramide in 16%, 10%, and 10% of patients, respectively. Pacing with short atrioventricular delay controlled symptoms in 4 of 9 patients. In 63% of patients, conservative measures failed to control symptoms. Multivariate predictors of failure of conservative therapy were presence of New York Heart Association class III or IV symptoms (hazard ratio 2.0, 95% confidence interval 1.4 to 2.9, p = 0.001) and greater septal wall thickness (hazard ratio 1.06, 95% confidence interval 1.02 to 1.10, p = 0.003) at presentation. At time of presentation, 93 patients (37%) were already on optimal therapy and were referred for SRT. Of the remaining 156 patients who did not require immediate SRT, 93 (60%) were free from a recommendation for SRT at the end of the follow-up period. In conclusion, in symptomatic patients with obstructive HC, conservative therapy is successful in >1/3 of referred patients at 3.7-year follow-up, obviating SRT in these patients. Clinicians in programs offering SRT should optimize conservative therapy before recommending SRT.

Risk stratification for sudden cardiac death after septal myectomy

Background The importance of risk stratification for sudden cardiac death (SCD) after septal myectomy for hypertrophic obstructive cardiomyopathy (HOCM) has not been emphasized previously. Methods and results We report 2 patients with SCD or ventricular tachycardia (VT) after septal myectomy for HOCM in whom risk factors for SCD were identified following surgical myectomy. One received an implantable cardioverter-defibrillator (ICD), which subsequently provided appropriate discharges for VT. The other delayed ICD implantation and suffered SCD. Conclusion These cases emphasize the importance of risk stratification for SCD after septal myectomy for HOCM.

Clinical Correlates and Prognostic Value of Elevated Right Atrial Pressure in Patients With Hypertrophic Cardiomyopathy

BACKGROUND The clinical characteristics associated with elevated right atrial pressure (RAP) in hypertrophic cardiomyopathy (HCM) are unknown. Few data exist as to whether elevated RAP has prognostic implications in patients with HCM. This study investigated the clinical correlates and prognostic value of elevated RAP in HCM.Methods and Results:This retrospective cohort study was performed on 180 patients with HCM who underwent right heart catheterization between 1997 and 2014. Elevated RAP was defined as >8 mmHg. Baseline characteristics, mean pulmonary artery pressure, and mean pulmonary capillary wedge pressure (PCWP) were assessed for association with elevated RAP. The predictive value of elevated RAP for all-cause mortality and the development of atrial fibrillation (AF), ventricular tachycardia/fibrillation (VT/VF), and stroke was evaluated. Elevated RAP was associated with higher New York Heart Association class, dyspnea on exertion, orthopnea, edema, jugular venous distention, larger left atrial size, right ventricular hypertrophy, higher pulmonary artery pressure, and higher PCWP. RAP independently predicted all-cause mortality (adjusted hazard ratio [aHR] 2.18 per 5-mmHg increase, 95% confidence interval [CI] 1.05-4.50, P=0.04) and incident AF (aHR 1.85 per 5-mmHg increase, 95% CI 1.20-2.85, P=0.005). Elevated RAP did not predict VT/VF (P=0.36) or stroke (P=0.28). CONCLUSIONS Elevated RAP in patients with HCM is associated with left-sided heart failure and is an independent predictor of all-cause mortality and new-onset AF.