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BackgroundIvabradine improves cardiac function in patients with heart failure, but its effect on dilated cardiomyopathy (DCM) remains unclear. We performed a systematic review and meta-analysis to study the efficacy and potential mechanisms of ivabradine's effect on cardiac function and prognosis in patients with DCM.MethodsWe searched PubMed, Cochrane Library, Embase, Web of Science, and four registers through September 28, 2022. All controlled trials of ivabradine for the treatment of DCM with congestive heart failure were included. Articles were limited to English, with the full text and necessary data available. We performed random- or fixed effects meta-analyses for all included outcome measures and compared the effect sizes for outcomes in patients treated with and without ivabradine. The quality of the studies was assessed using the Cochrane risk-of-bias tool for randomized trials (RoB2.0).FindingsFive trials with 357 participants were included. The pooled risk ratio was 0.48 [95% confidence interval (CI) (0.18, 1.25)] for all-cause mortality and 0.38 [95% CI (0.12, 1.23)] for cardiac mortality. The pooled mean difference was −15.95 [95% CI (−19.97, −11.92)] for resting heart rate, 3.96 [95% CI (0.99, 6.93)] for systolic blood pressure, 2.93 [95% CI (2.09, 3.77)] for left ventricular ejection fraction, −5.90 [95% CI (−9.36, −2.44)] for left ventricular end-systolic diameter, −3.41 [95% CI (−5.24, −1.58)] for left ventricular end-diastolic diameter, −0.81 [95% CI (−1.00, −0.62)] for left ventricular end-systolic volume, −0.67 [95% CI (−0.86, −0.48)] for left ventricular end-diastolic volume, −11.01 [95% CI (−19.66, −2.35)] for Minnesota Living with Heart Failure score, and −0.52 [95% CI (−0.73, −0.31)] for New York Heart Association class.InterpretationIvabradine reduces heart rate and ventricular volume, and improves cardiac function in patients with DCM, but showed no significant effect on the prognosis of patients.

IntroductionCardiopulmonary exercise test (CPET) provides the means to evaluate the cardiopulmonary function and guide cardiac rehabilitation. The performance of acute myocardial infarction (AMI) patients at different times is different on CPET.Materials and methodsThis was a cross-sectional study. Patients diagnosed as AMI in stable status were included and performed the low- level CPET (RAMP 10W). CPET variables at different times were compared among four groups.ResultsSixty and one patients with AMI conducted the low-level CPET from 3 to 15 days after AMI. Patients were stratified according to quartiles of CPET's time: 5 in 3–6 days group, 34 in 7–9 days group, 14 in 10–12 days group, 8 in 13–15 days group. Only VO2/HR at rest showed statistically different among the four groups.VO2/HR at rest in 3–6 days group and 10–12 days group were higher than in 13–15 days group (3.4 ± 0.85, 3.18 ± 0.78 vs. 2.50 ± 0.49 ml/beat, p < 0.05). Patients with complete revascularization had higher peak heart rate and blood pressure product and peak breathing reserve (BR), and lower Borg score compared with incomplete revascularization. And patients with LVEF >50% had higher peak BR compared with LVEF 40–50%.ConclusionIt was safe and efficient to conduct the low-level CPET in stable AMI patients 3 days after onset. Time was not an effector on cardiopulmonary function and exercise capacity and prognosis in AMI during CPET. Complete revascularization and normal LVEF should be good for exercise test in AMI.

It is arduous to determine clinical solutions for Andersen-Tawil syndrome (ATS) in patients intolerant of β-blocker. Here, we present the case of a 7-year-old boy with periodic paralysis and dysmorphic features who experienced syncope four times during exercise. His ECG revealed enlarged U waves and QU-prolongation associated with ATS-specific U wave patterns, frequent PVCs, and non-sustained bidirectional or polymorphic ventricular tachycardia. The genetic test showed a de novo missense R218W mutation of KCNJ2. With the diagnosis of ATS and intolerance of β-blocker, the patient was prescribed oral medications of mexiletine 450 mg/day without severe adverse effects. The repeat ECG showed decreased PVC burden from 38 to 3% and absence of ventricular tachycardia. He remained symptom-free during over 2 years of outpatient follow-up. This case demonstrates a new anti-arrhythmic therapy with mexiletine for prevention of life-threatening cardiac events in patients with ATS who are intolerant of β-blocker treatment.