Asymptomatic left ventricular dysfunction as an expression of stage B heart failure, a precursor to clinical heart failure, appears common in elderly patients with type 2 diabetes, and impaired global longitudinal strain may have incremental prognostic value, a recent study indicated.
Researchers in Tasmania, Australia, performed a prospective study of asymptomatic patients with type 2 diabetes who were 65 years of age and older and had preserved left ventricular ejection fraction to determine whether impaired global longitudinal strain, diastolic dysfunction, or left atrial enlargement helped indicate the presence of stage B heart failure. Patients were recruited from the community via newspaper advertising. Absolute risk of heart failure at three years was estimated by using the Atherosclerosis Risk in Communities (ARIC) score, and all patients underwent comprehensive echocardiography in accordance with American Society of Echocardiography guidelines.
Potential heart failure symptoms during follow-up were identified with phone calls and surveys. Diagnosis of incident heart failure was determined by the consensus of three independent cardiologists according to the Framingham heart failure criteria. The study's primary composite end point was new-onset heart failure and all-cause mortality. Results were published May 16 by JACC: Cardiovascular Imaging.
A total of 290 patients completed a median follow-up of 1.5 years. The mean age was 71 years, and 56% were men. Seventy-seven percent had hypertension, 49% were obese, 31% had a family history of heart failure, 8% had been exposed to chemotherapy, and 7% had a history of heart disease. Left ventricular dysfunction was detected in 30 patients (10%) by diastolic dysfunction, in 68 patients (23%) by left ventricular hypertrophy, in 102 patients (35%) by left atrial enlargement, and in 68 patients (23%) by impaired global longitudinal strain.
Forty-five patients developed new-onset heart failure, and of these, four died (event rate, 112/1,000 person-years). Compared with patients who had abnormal results on echocardiography, those who had normal results had 1.5-fold higher rate of survival free of the composite endpoint. Left ventricular hypertrophy, left atrial enlargement, and a global longitudinal strain below 16% were associated with increased risk. When left atrial volume and global longitudinal strain were added to ARIC score and left ventricular hypertrophy, incremental prognostic value was noted. Left ventricular hypertrophy and global longitudinal strain below 16% were associated with incident heart failure in a competing-risks regression analysis, but diastolic dysfunction and left atrial enlargement were not.
The researchers noted that the study population was self-selected, which may have resulted in population selection bias, and that no data were collected on biomarkers such as natriuretic peptides, among other limitations. However, they concluded that asymptomatic left ventricular systolic dysfunction as an expression of stage B heart failure is common in this group of patients and that certain indicators, such as impaired global longitudinal strain, may increase prognostic value.
“The detection of early myocardial dysfunction may allow identification of asymptomatic patients with [type 2 diabetes mellitus] who are at risk of developing symptomatic [heart failure],” the authors wrote.
An accompanying editorial said that the study adds to the growing literature on identification and risk stratification among patients with stage B heart failure but noted that it may not be applicable to younger patients, since the included population was 65 years of age and older. The editorialists discussed the emerging usefulness of strain imaging, particularly global longitudinal strain for early detection of cardiac dysfunction, and highlighted questions that remain to be answered, including whether the variables in this study should be added to definitions of structural heart disease and stage B heart failure and whether patients with stage B heart failure need to be further stratified by risk of progression to stage C.
The editorialists also raised the question of whether biochemical measures of cardiac dysfunction should routinely and periodically be assessed in patients with diabetes.
“Stage B patients are often seen in primary care offices where the cost of biochemical testing would seem to [be] more cost effective than the added cost of echocardiography,” they wrote. “Further research including younger diabetic adult patients, cost effectiveness analysis and implications on therapy are needed to evaluate the clinical benefit of further risk stratification with [global longitudinal strain].”