The Response of the QT Interval to the Brief Tachycardia Provoked by Standing: A Bedside Test for Diagnosing Long QT Syndrome
Viskin S, Postema PG, Bhuiyan ZA, et al.
J Am Coll Cardiol 2010;Jan 27:[Epub ahead of print].
Study Question: Is the response of the QT interval during an orthostatic increase in sinus rate useful for the diagnosis of long QT syndrome (LQTS)?
Title: Relation Between Kidney Function, Proteinuria, and Adverse Outcomes
Topic: General Cardiology
Date Posted: 2/4/2010
Author(s): Hemmelgarn BR, Manns BJ, Lloyd A, et al., on behalf of the Alberta Kidney Disease Network.
Citation: JAMA 2010;303:423-429.
Clinical Trial: No
Study Question: What is the association between reduced glomerular filtration rate (GFR), proteinuria, and adverse clinical outcome?
Methods: The participants were from a community-based cohort study comprised of 920,985 adults who had at least one outpatient serum creatinine measurement and who did not require renal replacement treatment at baseline. Proteinuria was assessed by urine dipstick or albumin-creatinine ratio (ACR). All-cause mortality, myocardial infarction, and progression to kidney failure were the main outcome measures. The median follow-up period was 35 months (range 0-59 months).
Results: The investigators found that a majority of individuals (89.1%) had an estimated GFR (eGFR) of ≥60 ml/min/1.73 m2. Over a median follow-up of 35 months, 3% of the participants (n = 27,959) died. The fully adjusted rate of all-cause mortality was higher in study participants with lower eGFRs or heavier proteinuria. Adjusted mortality rates were more than twofold higher among individuals with heavy proteinuria measured by urine dipstick and eGFR of ≥60 ml/min/1.73 m2, as compared with those with eGFR of 45-59.9 ml/min/1.73 m2 and normal protein excretion (rate, 7.2 [95% CI, 6.6-7.8] vs. 2.9 [95% CI, 2.7-3.0] per 1,000 person-years, respectively; rate ratio, 2.5 [95% CI, 2.3-2.7]). Similar results were observed when proteinuria was measured by ACR (15.9 [95% CI, 14.0-18.1] and 7.0 [95% CI, 6.4-7.6] per 1,000 person-years for heavy and absent proteinuria, respectively; rate ratio, 2.3 [95% CI, 2.0-2.6]) and for the outcomes of hospitalization with acute myocardial infarction, end-stage renal disease, and doubling of serum creatinine level.
Conclusions: The authors concluded that risks of mortality, myocardial infarction, and progression to kidney failure associated with a given level of eGFR are independently increased in patients with higher levels of proteinuria.
Perspective: Proteinuria and eGFR are two ‘independent’ (i.e., they do not go hand in hand) indicators of renal disease, and this study suggests that when both are abnormal, poorer outcomes, including all-cause mortality, progression to kidney failure, and acute myocardial infarction, are more likely to occur. The CHARM study suggested that proteinuria (spot urinary albumin-to-creatinine ratio) is an important prognostic predictor in patients with heart failure (Lancet 2009;374:543-550). Clearly the next step is to prevent target-organ damage, particularly prevention and control of diabetes and hypertension. The MICRO-HOPE (Lancet 2000;355:253-259) study suggested that angiotensin-converting enzyme inhibitor therapy with ramipril in diabetics is associated with a lower incidence of nephropathy. Ragavendra R. Baliga, M.B.B.S.
Title: N-Terminal Pro–B-Type Natriuretic Peptide-Guided Treatment for Chronic Heart Failure: Results From the BATTLESCARRED (NT-proBNP–Assisted Treatment To Lessen Serial Cardiac Readmissions and Death) Trial
Topic: Heart Failure/Transplant
Date Posted: 2/2/2010
Author(s): Lainchbury JG, Troughton RW, Strangman KM, et al.
Citation: J Am Coll Cardiol 2010;55:53-60.
Clinical Trial: yes
Study Question: What are the effects of N-terminal pro–B-type natriuretic peptide (NT-proBNP)-guided therapy on clinical outcomes in heart failure (HF)?
Methods: The study cohort included 364 HF patients admitted to a single hospital for HF. The investigators randomly allocated 1:1:1 (stratified by age) to therapy guided by NT-proBNP levels or by intensive clinical management, or according to usual care (UC). The therapeutic strategies were applied for 2 years, with a follow-up period of 3 years.
Results: The investigators found that 1-year mortality was less in both the NT-proBNP- (9.1%) and clinically-guided (9.1%) groups compared with UC (18.9%; p = 0.03). Three-year mortality was selectively reduced in patients ≤75 years of age receiving NT-proBNP–guided therapy (15.5%) compared with their peers receiving either clinically managed treatment (30.9%; p = 0.048) or UC (31.3%; p = 0.021).
Conclusions: The authors concluded that intensive management of HF improves 1-year mortality compared with UC. Compared with clinically guided treatment and UC, NT-proBNP–guided treatment selectively improves longer-term mortality in patients ≤75 years of age.
Perspective: This is an important study because it supports the findings from the STARS-BNP study, which showed that titrating BNP therapy to <100 pg/ml reduced the composite endpoint of mortality and hospitalization due to HF compared with guideline-directed therapy. Ragavendra R. Baliga, M.B.B.S.