Research Spotlight

Packer, M. (2019). “Nonarrhythmic Sudden Cardiac Death in Chronic Heart Failure-A Preventable Event?” JAMA Cardiol Jul 17. [Epub ahead of print].

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Sudden cardiac death is the mode of demise in 30% to 50% of patients with chronic heart failure with reduced ejection fraction. Traditionally, physicians have assumed that the abrupt collapse of the circulation is invariably caused by sustained ventricular tachycardia or fibrillation. These arrhythmias may occur without an identifiable trigger or be precipitated by a circadian catecholamine surge, electrolyte imbalances, or the use of drugs with proarrhythmic effects. Regardless of the cause, sustained ventricular tachyarrhythmias are highly responsive to treatment with an implantable cardioverter-defibrillator (ICD). Implantable cardioverter-defibrillators are recommended for patients with heart failure who demonstrate persistent systolic dysfunction after treatment with neurohormonal antagonists and in whom nonsudden deaths are not an important competing short-term risk for demise.

Roberts, W. C. (2019). “Frequency of Left Ventricular Scars at Autopsy in Persons Dying Suddenly of Coronary Artery Disease With or Without Earlier Myocardial Infarction.” JAMA Cardiol Jul 10. [Epub ahead of print].

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In this issue of JAMA Cardiology, Vähätalo et al. investigated through clinical and autopsy records 5869 persons who had died suddenly of nontraumatic causes in northern Finland during a recent 20-year period. The deaths of 4392 individuals (74.8%) were attributed to coronary artery disease (CAD) and the deaths of 1477 individuals (25.2%) to non-CAD conditions. Of the 4392 individuals who died of CAD, 3122 (71.1%) had no prior diagnosis of CAD, per the authors, and 1026 (23.4%) had a prior CAD diagnosis. Of the 3122 with no prior CAD diagnosis, 1322 individuals (42.4%) had a left ventricular (LV) scar at autopsy, and 1798 (57.6%) did not. The article compares clinical and cardiac morphologic findings in those with vs those without an LV scar at autopsy. The scars, of course, indicate that those individuals had had an acute myocardial infarction (MI) that had healed: in 42.4%, the acute MI apparently was not recognized during life (which is called a silent MI). There were no significant differences between the 2 groups in frequency of diabetes mellitus (249 of 1322 [18.8%] vs 312 of 1798 [17.4%]), systemic hypertension (523 [39.6%] vs 688 [38.3%]), dyslipidemia (149 [11.3%] vs 200 [11.1%]), angina pectoris (81 [6.1%] vs 104 [5.8%]), or dyspnea (45 [3.4%] vs 53 [2.9%]). There were statistically different but not clinically meaningful differences between those with vs those without LV scars in mean (SD) age (66.9 [11.1] years vs 65.5 [11.6] years; P = .001) and heart weight (mean [SD]: men, 497.2 [107.0] g vs 454.7 [105.0] g; P < .001; women, 411.3 [85.7] g vs 386.1 [91.2] g; P = .001) and frequencies of total occlusion of a coronary artery (519 of 1322 [39.3%] vs 291 of 1798 [16.2%]; P < .001), occurrence of sudden death during physical activity (241 of 1322 [18.2%] vs 223 of 1798 [12.4%]; P < .001), and occurrence of the sudden death event outside (265 of 1322 [20.0%] vs 268 of 1798 [14.9%]; P = .001).

Cedars, A., K. M. Tecson, A. N. Zaidi, A. Lorts and P. A. McCullough (2019). “Impact of Durable Ventricular Assist Device Support on Outcomes of Patients with Congenital Heart Disease Waiting for Heart Transplant.” ASAIO J Jul 15. [Epub ahead of print].

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The number of congenital heart disease (CHD) patients with heart failure is expanding. These patients have a high probability of dying, while awaiting heart transplant. The potential for durable ventricular assist devices (VAD) to improve waiting list survival in CHD is unknown. We conducted an analysis of the Scientific Registry of Transplant Recipients database for the primary outcome of death or delisting due to clinical worsening, while listed for heart transplant. We compared CHD patients with non-CHD patients matched for listing status. Multivariable models were constructed to account for confounding variables. Congenital heart disease patients were less likely to have a VAD and were more likely to experience the primary outcome of death or delisting due to clinical worsening compared to non-CHD patients. Ventricular assist devices decreased the probability of experiencing the primary outcome for non-CHD but not for CHD patients with a final listing status of 1A. Ventricular assist devices increased the probability of experiencing the primary outcome among CHD patients for those with a final listing status of 1B with no impact in non-CHD patients. Among non-CHD patients who died or were delisted, the time to the primary outcome was delayed by VAD, with a similar trend in CHD. Except for patients with a final listing status of 1B, VAD does not adversely affect waiting list outcomes in CHD patients listed for heart transplant. Ventricular assist devices may prolong waiting list survival among high-risk CHD patients.

van der Knaap, M. S., R. Schiffmann, F. Mochel and N. I. Wolf (2019). “Diagnosis, prognosis, and treatment of leukodystrophies.” Lancet Neurol Jul 12. [Epub ahead of print].

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Leukodystrophies comprise a large group of rare genetic disorders primarily affecting CNS white matter. Historically, the diagnostic process was slow and patient prognosis regarded as poor because curative treatment was only available for very few leukodystrophies in early stages of the disease. Whole-exome sequencing has both greatly increased the number of known leukodystrophies and improved diagnosis. Whether MRI keeps its central place in diagnosis and what the role is of whole-exome sequencing are relevant questions for neurologists. Improved diagnosis has revealed the phenotypic variability of leukodystrophies, requiring adaptation of prognostication. Technological advance in molecular techniques and improved insight into the pathophysiology of individual leukodystrophies have led to therapeutic developments, including drug design and gene therapy. Despite this progress, therapies are only beneficial early in the disease course, emphasising the need for a speedy diagnosis and for research on regenerative approaches to repair the damage already present.

Schiller, L. R. (2019). “Chronic Diarrhea Evaluation in the Elderly: IBS or Something Else?” Curr Gastroenterol Rep 21(9): 45.

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PURPOSE OF REVIEW: Chronic diarrhea is a common problem in all age groups but is a particularly challenging diagnostic problem in the elderly, since many different conditions need to be considered. The purpose of this review is to discuss the evaluation of chronic diarrhea in older individuals. It highlights those conditions that seem to occur with increased frequency in the elderly, discusses the diagnostic tests that are of greatest value in sorting out these problems, and presents an approach to evaluation that is both practical and affordable. RECENT FINDINGS: There appears to be little value in distinguishing irritable bowel syndrome with diarrhea (IBS-D) from functional diarrhea in most patients, including older individuals. Both conditions need a thoughtful analysis of potential causes that may lead to more focused treatment. Older individuals may be more at risk of having certain structural disorders, and these need to be considered when constructing a differential diagnosis. In addition, elderly patients may have atypical presentations of specific disorders that require an increased index of suspicion. Diagnostic tests generally seem to perform well in older patients but have not been validated in this cohort of patients. Although the pretest probabilities of certain diseases are different in the elderly, the conventional algorithm for assessment of chronic diarrhea should lead to a diagnosis in most cases. Better studies are needed to adequately quantitate the likelihood of different diagnoses and the operating characteristics of diagnostic tests in older patients with chronic diarrhea. Lacking that information, physicians can still do a good job of making a diagnosis in these patients by adopting a stepwise approach.